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Diffstat (limited to 'numpy/linalg/lapack_lite/f2c_s_lapack.c')
| -rw-r--r-- | numpy/linalg/lapack_lite/f2c_s_lapack.c | 34925 |
1 files changed, 34925 insertions, 0 deletions
diff --git a/numpy/linalg/lapack_lite/f2c_s_lapack.c b/numpy/linalg/lapack_lite/f2c_s_lapack.c new file mode 100644 index 000000000..454ac8ab7 --- /dev/null +++ b/numpy/linalg/lapack_lite/f2c_s_lapack.c @@ -0,0 +1,34925 @@ +/* +NOTE: This is generated code. Look in Misc/lapack_lite for information on + remaking this file. +*/ +#include "f2c.h" + +#ifdef HAVE_CONFIG +#include "config.h" +#else +extern doublereal dlamch_(char *); +#define EPSILON dlamch_("Epsilon") +#define SAFEMINIMUM dlamch_("Safe minimum") +#define PRECISION dlamch_("Precision") +#define BASE dlamch_("Base") +#endif + +extern doublereal dlapy2_(doublereal *x, doublereal *y); + +/* +f2c knows the exact rules for precedence, and so omits parentheses where not +strictly necessary. Since this is generated code, we don't really care if +it's readable, and we know what is written is correct. So don't warn about +them. +*/ +#if defined(__GNUC__) +#pragma GCC diagnostic ignored "-Wparentheses" +#endif + + +/* Table of constant values */ + +static integer c__9 = 9; +static integer c__0 = 0; +static real c_b15 = 1.f; +static integer c__1 = 1; +static real c_b29 = 0.f; +static doublereal c_b94 = -.125; +static real c_b151 = -1.f; +static integer c_n1 = -1; +static integer c__3 = 3; +static integer c__2 = 2; +static integer c__8 = 8; +static integer c__4 = 4; +static integer c__65 = 65; +static integer c__15 = 15; +static logical c_false = FALSE_; +static integer c__10 = 10; +static integer c__11 = 11; +static real c_b2521 = 2.f; +static logical c_true = TRUE_; + +/* Subroutine */ int sbdsdc_(char *uplo, char *compq, integer *n, real *d__, + real *e, real *u, integer *ldu, real *vt, integer *ldvt, real *q, + integer *iq, real *work, integer *iwork, integer *info) +{ + /* System generated locals */ + integer u_dim1, u_offset, vt_dim1, vt_offset, i__1, i__2; + real r__1; + + /* Builtin functions */ + double r_sign(real *, real *), log(doublereal); + + /* Local variables */ + static integer i__, j, k; + static real p, r__; + static integer z__, ic, ii, kk; + static real cs; + static integer is, iu; + static real sn; + static integer nm1; + static real eps; + static integer ivt, difl, difr, ierr, perm, mlvl, sqre; + extern logical lsame_(char *, char *); + static integer poles; + extern /* Subroutine */ int slasr_(char *, char *, char *, integer *, + integer *, real *, real *, real *, integer *); + static integer iuplo, nsize, start; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *), sswap_(integer *, real *, integer *, real *, integer * + ), slasd0_(integer *, integer *, real *, real *, real *, integer * + , real *, integer *, integer *, integer *, real *, integer *); + extern doublereal slamch_(char *); + extern /* Subroutine */ int slasda_(integer *, integer *, integer *, + integer *, real *, real *, real *, integer *, real *, integer *, + real *, real *, real *, real *, integer *, integer *, integer *, + integer *, real *, real *, real *, real *, integer *, integer *), + xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *, + real *, integer *, integer *, real *, integer *, integer *); + static integer givcol; + extern /* Subroutine */ int slasdq_(char *, integer *, integer *, integer + *, integer *, integer *, real *, real *, real *, integer *, real * + , integer *, real *, integer *, real *, integer *); + static integer icompq; + extern /* Subroutine */ int slaset_(char *, integer *, integer *, real *, + real *, real *, integer *), slartg_(real *, real *, real * + , real *, real *); + static real orgnrm; + static integer givnum; + extern doublereal slanst_(char *, integer *, real *, real *); + static integer givptr, qstart, smlsiz, wstart, smlszp; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + December 1, 1999 + + + Purpose + ======= + + SBDSDC computes the singular value decomposition (SVD) of a real + N-by-N (upper or lower) bidiagonal matrix B: B = U * S * VT, + using a divide and conquer method, where S is a diagonal matrix + with non-negative diagonal elements (the singular values of B), and + U and VT are orthogonal matrices of left and right singular vectors, + respectively. SBDSDC can be used to compute all singular values, + and optionally, singular vectors or singular vectors in compact form. + + This code makes very mild assumptions about floating point + arithmetic. It will work on machines with a guard digit in + add/subtract, or on those binary machines without guard digits + which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or Cray-2. + It could conceivably fail on hexadecimal or decimal machines + without guard digits, but we know of none. See SLASD3 for details. + + The code currently call SLASDQ if singular values only are desired. + However, it can be slightly modified to compute singular values + using the divide and conquer method. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + = 'U': B is upper bidiagonal. + = 'L': B is lower bidiagonal. + + COMPQ (input) CHARACTER*1 + Specifies whether singular vectors are to be computed + as follows: + = 'N': Compute singular values only; + = 'P': Compute singular values and compute singular + vectors in compact form; + = 'I': Compute singular values and singular vectors. + + N (input) INTEGER + The order of the matrix B. N >= 0. + + D (input/output) REAL array, dimension (N) + On entry, the n diagonal elements of the bidiagonal matrix B. + On exit, if INFO=0, the singular values of B. + + E (input/output) REAL array, dimension (N) + On entry, the elements of E contain the offdiagonal + elements of the bidiagonal matrix whose SVD is desired. + On exit, E has been destroyed. + + U (output) REAL array, dimension (LDU,N) + If COMPQ = 'I', then: + On exit, if INFO = 0, U contains the left singular vectors + of the bidiagonal matrix. + For other values of COMPQ, U is not referenced. + + LDU (input) INTEGER + The leading dimension of the array U. LDU >= 1. + If singular vectors are desired, then LDU >= max( 1, N ). + + VT (output) REAL array, dimension (LDVT,N) + If COMPQ = 'I', then: + On exit, if INFO = 0, VT' contains the right singular + vectors of the bidiagonal matrix. + For other values of COMPQ, VT is not referenced. + + LDVT (input) INTEGER + The leading dimension of the array VT. LDVT >= 1. + If singular vectors are desired, then LDVT >= max( 1, N ). + + Q (output) REAL array, dimension (LDQ) + If COMPQ = 'P', then: + On exit, if INFO = 0, Q and IQ contain the left + and right singular vectors in a compact form, + requiring O(N log N) space instead of 2*N**2. + In particular, Q contains all the REAL data in + LDQ >= N*(11 + 2*SMLSIZ + 8*INT(LOG_2(N/(SMLSIZ+1)))) + words of memory, where SMLSIZ is returned by ILAENV and + is equal to the maximum size of the subproblems at the + bottom of the computation tree (usually about 25). + For other values of COMPQ, Q is not referenced. + + IQ (output) INTEGER array, dimension (LDIQ) + If COMPQ = 'P', then: + On exit, if INFO = 0, Q and IQ contain the left + and right singular vectors in a compact form, + requiring O(N log N) space instead of 2*N**2. + In particular, IQ contains all INTEGER data in + LDIQ >= N*(3 + 3*INT(LOG_2(N/(SMLSIZ+1)))) + words of memory, where SMLSIZ is returned by ILAENV and + is equal to the maximum size of the subproblems at the + bottom of the computation tree (usually about 25). + For other values of COMPQ, IQ is not referenced. + + WORK (workspace) REAL array, dimension (LWORK) + If COMPQ = 'N' then LWORK >= (4 * N). + If COMPQ = 'P' then LWORK >= (6 * N). + If COMPQ = 'I' then LWORK >= (3 * N**2 + 4 * N). + + IWORK (workspace) INTEGER array, dimension (8*N) + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: The algorithm failed to compute an singular value. + The update process of divide and conquer failed. + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --e; + u_dim1 = *ldu; + u_offset = 1 + u_dim1; + u -= u_offset; + vt_dim1 = *ldvt; + vt_offset = 1 + vt_dim1; + vt -= vt_offset; + --q; + --iq; + --work; + --iwork; + + /* Function Body */ + *info = 0; + + iuplo = 0; + if (lsame_(uplo, "U")) { + iuplo = 1; + } + if (lsame_(uplo, "L")) { + iuplo = 2; + } + if (lsame_(compq, "N")) { + icompq = 0; + } else if (lsame_(compq, "P")) { + icompq = 1; + } else if (lsame_(compq, "I")) { + icompq = 2; + } else { + icompq = -1; + } + if (iuplo == 0) { + *info = -1; + } else if (icompq < 0) { + *info = -2; + } else if (*n < 0) { + *info = -3; + } else if (*ldu < 1 || icompq == 2 && *ldu < *n) { + *info = -7; + } else if (*ldvt < 1 || icompq == 2 && *ldvt < *n) { + *info = -9; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SBDSDC", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + smlsiz = ilaenv_(&c__9, "SBDSDC", " ", &c__0, &c__0, &c__0, &c__0, ( + ftnlen)6, (ftnlen)1); + if (*n == 1) { + if (icompq == 1) { + q[1] = r_sign(&c_b15, &d__[1]); + q[smlsiz * *n + 1] = 1.f; + } else if (icompq == 2) { + u[u_dim1 + 1] = r_sign(&c_b15, &d__[1]); + vt[vt_dim1 + 1] = 1.f; + } + d__[1] = dabs(d__[1]); + return 0; + } + nm1 = *n - 1; + +/* + If matrix lower bidiagonal, rotate to be upper bidiagonal + by applying Givens rotations on the left +*/ + + wstart = 1; + qstart = 3; + if (icompq == 1) { + scopy_(n, &d__[1], &c__1, &q[1], &c__1); + i__1 = *n - 1; + scopy_(&i__1, &e[1], &c__1, &q[*n + 1], &c__1); + } + if (iuplo == 2) { + qstart = 5; + wstart = (*n << 1) - 1; + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + slartg_(&d__[i__], &e[i__], &cs, &sn, &r__); + d__[i__] = r__; + e[i__] = sn * d__[i__ + 1]; + d__[i__ + 1] = cs * d__[i__ + 1]; + if (icompq == 1) { + q[i__ + (*n << 1)] = cs; + q[i__ + *n * 3] = sn; + } else if (icompq == 2) { + work[i__] = cs; + work[nm1 + i__] = -sn; + } +/* L10: */ + } + } + +/* If ICOMPQ = 0, use SLASDQ to compute the singular values. */ + + if (icompq == 0) { + slasdq_("U", &c__0, n, &c__0, &c__0, &c__0, &d__[1], &e[1], &vt[ + vt_offset], ldvt, &u[u_offset], ldu, &u[u_offset], ldu, &work[ + wstart], info); + goto L40; + } + +/* + If N is smaller than the minimum divide size SMLSIZ, then solve + the problem with another solver. +*/ + + if (*n <= smlsiz) { + if (icompq == 2) { + slaset_("A", n, n, &c_b29, &c_b15, &u[u_offset], ldu); + slaset_("A", n, n, &c_b29, &c_b15, &vt[vt_offset], ldvt); + slasdq_("U", &c__0, n, n, n, &c__0, &d__[1], &e[1], &vt[vt_offset] + , ldvt, &u[u_offset], ldu, &u[u_offset], ldu, &work[ + wstart], info); + } else if (icompq == 1) { + iu = 1; + ivt = iu + *n; + slaset_("A", n, n, &c_b29, &c_b15, &q[iu + (qstart - 1) * *n], n); + slaset_("A", n, n, &c_b29, &c_b15, &q[ivt + (qstart - 1) * *n], n); + slasdq_("U", &c__0, n, n, n, &c__0, &d__[1], &e[1], &q[ivt + ( + qstart - 1) * *n], n, &q[iu + (qstart - 1) * *n], n, &q[ + iu + (qstart - 1) * *n], n, &work[wstart], info); + } + goto L40; + } + + if (icompq == 2) { + slaset_("A", n, n, &c_b29, &c_b15, &u[u_offset], ldu); + slaset_("A", n, n, &c_b29, &c_b15, &vt[vt_offset], ldvt); + } + +/* Scale. */ + + orgnrm = slanst_("M", n, &d__[1], &e[1]); + if (orgnrm == 0.f) { + return 0; + } + slascl_("G", &c__0, &c__0, &orgnrm, &c_b15, n, &c__1, &d__[1], n, &ierr); + slascl_("G", &c__0, &c__0, &orgnrm, &c_b15, &nm1, &c__1, &e[1], &nm1, & + ierr); + + eps = slamch_("Epsilon"); + + mlvl = (integer) (log((real) (*n) / (real) (smlsiz + 1)) / log(2.f)) + 1; + smlszp = smlsiz + 1; + + if (icompq == 1) { + iu = 1; + ivt = smlsiz + 1; + difl = ivt + smlszp; + difr = difl + mlvl; + z__ = difr + (mlvl << 1); + ic = z__ + mlvl; + is = ic + 1; + poles = is + 1; + givnum = poles + (mlvl << 1); + + k = 1; + givptr = 2; + perm = 3; + givcol = perm + mlvl; + } + + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + if ((r__1 = d__[i__], dabs(r__1)) < eps) { + d__[i__] = r_sign(&eps, &d__[i__]); + } +/* L20: */ + } + + start = 1; + sqre = 0; + + i__1 = nm1; + for (i__ = 1; i__ <= i__1; ++i__) { + if ((r__1 = e[i__], dabs(r__1)) < eps || i__ == nm1) { + +/* + Subproblem found. First determine its size and then + apply divide and conquer on it. +*/ + + if (i__ < nm1) { + +/* A subproblem with E(I) small for I < NM1. */ + + nsize = i__ - start + 1; + } else if ((r__1 = e[i__], dabs(r__1)) >= eps) { + +/* A subproblem with E(NM1) not too small but I = NM1. */ + + nsize = *n - start + 1; + } else { + +/* + A subproblem with E(NM1) small. This implies an + 1-by-1 subproblem at D(N). Solve this 1-by-1 problem + first. +*/ + + nsize = i__ - start + 1; + if (icompq == 2) { + u[*n + *n * u_dim1] = r_sign(&c_b15, &d__[*n]); + vt[*n + *n * vt_dim1] = 1.f; + } else if (icompq == 1) { + q[*n + (qstart - 1) * *n] = r_sign(&c_b15, &d__[*n]); + q[*n + (smlsiz + qstart - 1) * *n] = 1.f; + } + d__[*n] = (r__1 = d__[*n], dabs(r__1)); + } + if (icompq == 2) { + slasd0_(&nsize, &sqre, &d__[start], &e[start], &u[start + + start * u_dim1], ldu, &vt[start + start * vt_dim1], + ldvt, &smlsiz, &iwork[1], &work[wstart], info); + } else { + slasda_(&icompq, &smlsiz, &nsize, &sqre, &d__[start], &e[ + start], &q[start + (iu + qstart - 2) * *n], n, &q[ + start + (ivt + qstart - 2) * *n], &iq[start + k * *n], + &q[start + (difl + qstart - 2) * *n], &q[start + ( + difr + qstart - 2) * *n], &q[start + (z__ + qstart - + 2) * *n], &q[start + (poles + qstart - 2) * *n], &iq[ + start + givptr * *n], &iq[start + givcol * *n], n, & + iq[start + perm * *n], &q[start + (givnum + qstart - + 2) * *n], &q[start + (ic + qstart - 2) * *n], &q[ + start + (is + qstart - 2) * *n], &work[wstart], & + iwork[1], info); + if (*info != 0) { + return 0; + } + } + start = i__ + 1; + } +/* L30: */ + } + +/* Unscale */ + + slascl_("G", &c__0, &c__0, &c_b15, &orgnrm, n, &c__1, &d__[1], n, &ierr); +L40: + +/* Use Selection Sort to minimize swaps of singular vectors */ + + i__1 = *n; + for (ii = 2; ii <= i__1; ++ii) { + i__ = ii - 1; + kk = i__; + p = d__[i__]; + i__2 = *n; + for (j = ii; j <= i__2; ++j) { + if (d__[j] > p) { + kk = j; + p = d__[j]; + } +/* L50: */ + } + if (kk != i__) { + d__[kk] = d__[i__]; + d__[i__] = p; + if (icompq == 1) { + iq[i__] = kk; + } else if (icompq == 2) { + sswap_(n, &u[i__ * u_dim1 + 1], &c__1, &u[kk * u_dim1 + 1], & + c__1); + sswap_(n, &vt[i__ + vt_dim1], ldvt, &vt[kk + vt_dim1], ldvt); + } + } else if (icompq == 1) { + iq[i__] = i__; + } +/* L60: */ + } + +/* If ICOMPQ = 1, use IQ(N,1) as the indicator for UPLO */ + + if (icompq == 1) { + if (iuplo == 1) { + iq[*n] = 1; + } else { + iq[*n] = 0; + } + } + +/* + If B is lower bidiagonal, update U by those Givens rotations + which rotated B to be upper bidiagonal +*/ + + if (iuplo == 2 && icompq == 2) { + slasr_("L", "V", "B", n, n, &work[1], &work[*n], &u[u_offset], ldu); + } + + return 0; + +/* End of SBDSDC */ + +} /* sbdsdc_ */ + +/* Subroutine */ int sbdsqr_(char *uplo, integer *n, integer *ncvt, integer * + nru, integer *ncc, real *d__, real *e, real *vt, integer *ldvt, real * + u, integer *ldu, real *c__, integer *ldc, real *work, integer *info) +{ + /* System generated locals */ + integer c_dim1, c_offset, u_dim1, u_offset, vt_dim1, vt_offset, i__1, + i__2; + real r__1, r__2, r__3, r__4; + doublereal d__1; + + /* Builtin functions */ + double pow_dd(doublereal *, doublereal *), sqrt(doublereal), r_sign(real * + , real *); + + /* Local variables */ + static real f, g, h__; + static integer i__, j, m; + static real r__, cs; + static integer ll; + static real sn, mu; + static integer nm1, nm12, nm13, lll; + static real eps, sll, tol, abse; + static integer idir; + static real abss; + static integer oldm; + static real cosl; + static integer isub, iter; + static real unfl, sinl, cosr, smin, smax, sinr; + extern /* Subroutine */ int srot_(integer *, real *, integer *, real *, + integer *, real *, real *), slas2_(real *, real *, real *, real *, + real *); + extern logical lsame_(char *, char *); + static real oldcs; + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *); + static integer oldll; + static real shift, sigmn, oldsn; + static integer maxit; + static real sminl; + extern /* Subroutine */ int slasr_(char *, char *, char *, integer *, + integer *, real *, real *, real *, integer *); + static real sigmx; + static logical lower; + extern /* Subroutine */ int sswap_(integer *, real *, integer *, real *, + integer *), slasq1_(integer *, real *, real *, real *, integer *), + slasv2_(real *, real *, real *, real *, real *, real *, real *, + real *, real *); + extern doublereal slamch_(char *); + extern /* Subroutine */ int xerbla_(char *, integer *); + static real sminoa; + extern /* Subroutine */ int slartg_(real *, real *, real *, real *, real * + ); + static real thresh; + static logical rotate; + static real sminlo, tolmul; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1999 + + + Purpose + ======= + + SBDSQR computes the singular value decomposition (SVD) of a real + N-by-N (upper or lower) bidiagonal matrix B: B = Q * S * P' (P' + denotes the transpose of P), where S is a diagonal matrix with + non-negative diagonal elements (the singular values of B), and Q + and P are orthogonal matrices. + + The routine computes S, and optionally computes U * Q, P' * VT, + or Q' * C, for given real input matrices U, VT, and C. + + See "Computing Small Singular Values of Bidiagonal Matrices With + Guaranteed High Relative Accuracy," by J. Demmel and W. Kahan, + LAPACK Working Note #3 (or SIAM J. Sci. Statist. Comput. vol. 11, + no. 5, pp. 873-912, Sept 1990) and + "Accurate singular values and differential qd algorithms," by + B. Parlett and V. Fernando, Technical Report CPAM-554, Mathematics + Department, University of California at Berkeley, July 1992 + for a detailed description of the algorithm. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + = 'U': B is upper bidiagonal; + = 'L': B is lower bidiagonal. + + N (input) INTEGER + The order of the matrix B. N >= 0. + + NCVT (input) INTEGER + The number of columns of the matrix VT. NCVT >= 0. + + NRU (input) INTEGER + The number of rows of the matrix U. NRU >= 0. + + NCC (input) INTEGER + The number of columns of the matrix C. NCC >= 0. + + D (input/output) REAL array, dimension (N) + On entry, the n diagonal elements of the bidiagonal matrix B. + On exit, if INFO=0, the singular values of B in decreasing + order. + + E (input/output) REAL array, dimension (N) + On entry, the elements of E contain the + offdiagonal elements of the bidiagonal matrix whose SVD + is desired. On normal exit (INFO = 0), E is destroyed. + If the algorithm does not converge (INFO > 0), D and E + will contain the diagonal and superdiagonal elements of a + bidiagonal matrix orthogonally equivalent to the one given + as input. E(N) is used for workspace. + + VT (input/output) REAL array, dimension (LDVT, NCVT) + On entry, an N-by-NCVT matrix VT. + On exit, VT is overwritten by P' * VT. + VT is not referenced if NCVT = 0. + + LDVT (input) INTEGER + The leading dimension of the array VT. + LDVT >= max(1,N) if NCVT > 0; LDVT >= 1 if NCVT = 0. + + U (input/output) REAL array, dimension (LDU, N) + On entry, an NRU-by-N matrix U. + On exit, U is overwritten by U * Q. + U is not referenced if NRU = 0. + + LDU (input) INTEGER + The leading dimension of the array U. LDU >= max(1,NRU). + + C (input/output) REAL array, dimension (LDC, NCC) + On entry, an N-by-NCC matrix C. + On exit, C is overwritten by Q' * C. + C is not referenced if NCC = 0. + + LDC (input) INTEGER + The leading dimension of the array C. + LDC >= max(1,N) if NCC > 0; LDC >=1 if NCC = 0. + + WORK (workspace) REAL array, dimension (4*N) + + INFO (output) INTEGER + = 0: successful exit + < 0: If INFO = -i, the i-th argument had an illegal value + > 0: the algorithm did not converge; D and E contain the + elements of a bidiagonal matrix which is orthogonally + similar to the input matrix B; if INFO = i, i + elements of E have not converged to zero. + + Internal Parameters + =================== + + TOLMUL REAL, default = max(10,min(100,EPS**(-1/8))) + TOLMUL controls the convergence criterion of the QR loop. + If it is positive, TOLMUL*EPS is the desired relative + precision in the computed singular values. + If it is negative, abs(TOLMUL*EPS*sigma_max) is the + desired absolute accuracy in the computed singular + values (corresponds to relative accuracy + abs(TOLMUL*EPS) in the largest singular value. + abs(TOLMUL) should be between 1 and 1/EPS, and preferably + between 10 (for fast convergence) and .1/EPS + (for there to be some accuracy in the results). + Default is to lose at either one eighth or 2 of the + available decimal digits in each computed singular value + (whichever is smaller). + + MAXITR INTEGER, default = 6 + MAXITR controls the maximum number of passes of the + algorithm through its inner loop. The algorithms stops + (and so fails to converge) if the number of passes + through the inner loop exceeds MAXITR*N**2. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --e; + vt_dim1 = *ldvt; + vt_offset = 1 + vt_dim1; + vt -= vt_offset; + u_dim1 = *ldu; + u_offset = 1 + u_dim1; + u -= u_offset; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + *info = 0; + lower = lsame_(uplo, "L"); + if (! lsame_(uplo, "U") && ! lower) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*ncvt < 0) { + *info = -3; + } else if (*nru < 0) { + *info = -4; + } else if (*ncc < 0) { + *info = -5; + } else if (*ncvt == 0 && *ldvt < 1 || *ncvt > 0 && *ldvt < max(1,*n)) { + *info = -9; + } else if (*ldu < max(1,*nru)) { + *info = -11; + } else if (*ncc == 0 && *ldc < 1 || *ncc > 0 && *ldc < max(1,*n)) { + *info = -13; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SBDSQR", &i__1); + return 0; + } + if (*n == 0) { + return 0; + } + if (*n == 1) { + goto L160; + } + +/* ROTATE is true if any singular vectors desired, false otherwise */ + + rotate = *ncvt > 0 || *nru > 0 || *ncc > 0; + +/* If no singular vectors desired, use qd algorithm */ + + if (! rotate) { + slasq1_(n, &d__[1], &e[1], &work[1], info); + return 0; + } + + nm1 = *n - 1; + nm12 = nm1 + nm1; + nm13 = nm12 + nm1; + idir = 0; + +/* Get machine constants */ + + eps = slamch_("Epsilon"); + unfl = slamch_("Safe minimum"); + +/* + If matrix lower bidiagonal, rotate to be upper bidiagonal + by applying Givens rotations on the left +*/ + + if (lower) { + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + slartg_(&d__[i__], &e[i__], &cs, &sn, &r__); + d__[i__] = r__; + e[i__] = sn * d__[i__ + 1]; + d__[i__ + 1] = cs * d__[i__ + 1]; + work[i__] = cs; + work[nm1 + i__] = sn; +/* L10: */ + } + +/* Update singular vectors if desired */ + + if (*nru > 0) { + slasr_("R", "V", "F", nru, n, &work[1], &work[*n], &u[u_offset], + ldu); + } + if (*ncc > 0) { + slasr_("L", "V", "F", n, ncc, &work[1], &work[*n], &c__[c_offset], + ldc); + } + } + +/* + Compute singular values to relative accuracy TOL + (By setting TOL to be negative, algorithm will compute + singular values to absolute accuracy ABS(TOL)*norm(input matrix)) + + Computing MAX + Computing MIN +*/ + d__1 = (doublereal) eps; + r__3 = 100.f, r__4 = pow_dd(&d__1, &c_b94); + r__1 = 10.f, r__2 = dmin(r__3,r__4); + tolmul = dmax(r__1,r__2); + tol = tolmul * eps; + +/* Compute approximate maximum, minimum singular values */ + + smax = 0.f; + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { +/* Computing MAX */ + r__2 = smax, r__3 = (r__1 = d__[i__], dabs(r__1)); + smax = dmax(r__2,r__3); +/* L20: */ + } + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { +/* Computing MAX */ + r__2 = smax, r__3 = (r__1 = e[i__], dabs(r__1)); + smax = dmax(r__2,r__3); +/* L30: */ + } + sminl = 0.f; + if (tol >= 0.f) { + +/* Relative accuracy desired */ + + sminoa = dabs(d__[1]); + if (sminoa == 0.f) { + goto L50; + } + mu = sminoa; + i__1 = *n; + for (i__ = 2; i__ <= i__1; ++i__) { + mu = (r__2 = d__[i__], dabs(r__2)) * (mu / (mu + (r__1 = e[i__ - + 1], dabs(r__1)))); + sminoa = dmin(sminoa,mu); + if (sminoa == 0.f) { + goto L50; + } +/* L40: */ + } +L50: + sminoa /= sqrt((real) (*n)); +/* Computing MAX */ + r__1 = tol * sminoa, r__2 = *n * 6 * *n * unfl; + thresh = dmax(r__1,r__2); + } else { + +/* + Absolute accuracy desired + + Computing MAX +*/ + r__1 = dabs(tol) * smax, r__2 = *n * 6 * *n * unfl; + thresh = dmax(r__1,r__2); + } + +/* + Prepare for main iteration loop for the singular values + (MAXIT is the maximum number of passes through the inner + loop permitted before nonconvergence signalled.) +*/ + + maxit = *n * 6 * *n; + iter = 0; + oldll = -1; + oldm = -1; + +/* M points to last element of unconverged part of matrix */ + + m = *n; + +/* Begin main iteration loop */ + +L60: + +/* Check for convergence or exceeding iteration count */ + + if (m <= 1) { + goto L160; + } + if (iter > maxit) { + goto L200; + } + +/* Find diagonal block of matrix to work on */ + + if (tol < 0.f && (r__1 = d__[m], dabs(r__1)) <= thresh) { + d__[m] = 0.f; + } + smax = (r__1 = d__[m], dabs(r__1)); + smin = smax; + i__1 = m - 1; + for (lll = 1; lll <= i__1; ++lll) { + ll = m - lll; + abss = (r__1 = d__[ll], dabs(r__1)); + abse = (r__1 = e[ll], dabs(r__1)); + if (tol < 0.f && abss <= thresh) { + d__[ll] = 0.f; + } + if (abse <= thresh) { + goto L80; + } + smin = dmin(smin,abss); +/* Computing MAX */ + r__1 = max(smax,abss); + smax = dmax(r__1,abse); +/* L70: */ + } + ll = 0; + goto L90; +L80: + e[ll] = 0.f; + +/* Matrix splits since E(LL) = 0 */ + + if (ll == m - 1) { + +/* Convergence of bottom singular value, return to top of loop */ + + --m; + goto L60; + } +L90: + ++ll; + +/* E(LL) through E(M-1) are nonzero, E(LL-1) is zero */ + + if (ll == m - 1) { + +/* 2 by 2 block, handle separately */ + + slasv2_(&d__[m - 1], &e[m - 1], &d__[m], &sigmn, &sigmx, &sinr, &cosr, + &sinl, &cosl); + d__[m - 1] = sigmx; + e[m - 1] = 0.f; + d__[m] = sigmn; + +/* Compute singular vectors, if desired */ + + if (*ncvt > 0) { + srot_(ncvt, &vt[m - 1 + vt_dim1], ldvt, &vt[m + vt_dim1], ldvt, & + cosr, &sinr); + } + if (*nru > 0) { + srot_(nru, &u[(m - 1) * u_dim1 + 1], &c__1, &u[m * u_dim1 + 1], & + c__1, &cosl, &sinl); + } + if (*ncc > 0) { + srot_(ncc, &c__[m - 1 + c_dim1], ldc, &c__[m + c_dim1], ldc, & + cosl, &sinl); + } + m += -2; + goto L60; + } + +/* + If working on new submatrix, choose shift direction + (from larger end diagonal element towards smaller) +*/ + + if (ll > oldm || m < oldll) { + if ((r__1 = d__[ll], dabs(r__1)) >= (r__2 = d__[m], dabs(r__2))) { + +/* Chase bulge from top (big end) to bottom (small end) */ + + idir = 1; + } else { + +/* Chase bulge from bottom (big end) to top (small end) */ + + idir = 2; + } + } + +/* Apply convergence tests */ + + if (idir == 1) { + +/* + Run convergence test in forward direction + First apply standard test to bottom of matrix +*/ + + if ((r__2 = e[m - 1], dabs(r__2)) <= dabs(tol) * (r__1 = d__[m], dabs( + r__1)) || tol < 0.f && (r__3 = e[m - 1], dabs(r__3)) <= + thresh) { + e[m - 1] = 0.f; + goto L60; + } + + if (tol >= 0.f) { + +/* + If relative accuracy desired, + apply convergence criterion forward +*/ + + mu = (r__1 = d__[ll], dabs(r__1)); + sminl = mu; + i__1 = m - 1; + for (lll = ll; lll <= i__1; ++lll) { + if ((r__1 = e[lll], dabs(r__1)) <= tol * mu) { + e[lll] = 0.f; + goto L60; + } + sminlo = sminl; + mu = (r__2 = d__[lll + 1], dabs(r__2)) * (mu / (mu + (r__1 = + e[lll], dabs(r__1)))); + sminl = dmin(sminl,mu); +/* L100: */ + } + } + + } else { + +/* + Run convergence test in backward direction + First apply standard test to top of matrix +*/ + + if ((r__2 = e[ll], dabs(r__2)) <= dabs(tol) * (r__1 = d__[ll], dabs( + r__1)) || tol < 0.f && (r__3 = e[ll], dabs(r__3)) <= thresh) { + e[ll] = 0.f; + goto L60; + } + + if (tol >= 0.f) { + +/* + If relative accuracy desired, + apply convergence criterion backward +*/ + + mu = (r__1 = d__[m], dabs(r__1)); + sminl = mu; + i__1 = ll; + for (lll = m - 1; lll >= i__1; --lll) { + if ((r__1 = e[lll], dabs(r__1)) <= tol * mu) { + e[lll] = 0.f; + goto L60; + } + sminlo = sminl; + mu = (r__2 = d__[lll], dabs(r__2)) * (mu / (mu + (r__1 = e[ + lll], dabs(r__1)))); + sminl = dmin(sminl,mu); +/* L110: */ + } + } + } + oldll = ll; + oldm = m; + +/* + Compute shift. First, test if shifting would ruin relative + accuracy, and if so set the shift to zero. + + Computing MAX +*/ + r__1 = eps, r__2 = tol * .01f; + if (tol >= 0.f && *n * tol * (sminl / smax) <= dmax(r__1,r__2)) { + +/* Use a zero shift to avoid loss of relative accuracy */ + + shift = 0.f; + } else { + +/* Compute the shift from 2-by-2 block at end of matrix */ + + if (idir == 1) { + sll = (r__1 = d__[ll], dabs(r__1)); + slas2_(&d__[m - 1], &e[m - 1], &d__[m], &shift, &r__); + } else { + sll = (r__1 = d__[m], dabs(r__1)); + slas2_(&d__[ll], &e[ll], &d__[ll + 1], &shift, &r__); + } + +/* Test if shift negligible, and if so set to zero */ + + if (sll > 0.f) { +/* Computing 2nd power */ + r__1 = shift / sll; + if (r__1 * r__1 < eps) { + shift = 0.f; + } + } + } + +/* Increment iteration count */ + + iter = iter + m - ll; + +/* If SHIFT = 0, do simplified QR iteration */ + + if (shift == 0.f) { + if (idir == 1) { + +/* + Chase bulge from top to bottom + Save cosines and sines for later singular vector updates +*/ + + cs = 1.f; + oldcs = 1.f; + i__1 = m - 1; + for (i__ = ll; i__ <= i__1; ++i__) { + r__1 = d__[i__] * cs; + slartg_(&r__1, &e[i__], &cs, &sn, &r__); + if (i__ > ll) { + e[i__ - 1] = oldsn * r__; + } + r__1 = oldcs * r__; + r__2 = d__[i__ + 1] * sn; + slartg_(&r__1, &r__2, &oldcs, &oldsn, &d__[i__]); + work[i__ - ll + 1] = cs; + work[i__ - ll + 1 + nm1] = sn; + work[i__ - ll + 1 + nm12] = oldcs; + work[i__ - ll + 1 + nm13] = oldsn; +/* L120: */ + } + h__ = d__[m] * cs; + d__[m] = h__ * oldcs; + e[m - 1] = h__ * oldsn; + +/* Update singular vectors */ + + if (*ncvt > 0) { + i__1 = m - ll + 1; + slasr_("L", "V", "F", &i__1, ncvt, &work[1], &work[*n], &vt[ + ll + vt_dim1], ldvt); + } + if (*nru > 0) { + i__1 = m - ll + 1; + slasr_("R", "V", "F", nru, &i__1, &work[nm12 + 1], &work[nm13 + + 1], &u[ll * u_dim1 + 1], ldu); + } + if (*ncc > 0) { + i__1 = m - ll + 1; + slasr_("L", "V", "F", &i__1, ncc, &work[nm12 + 1], &work[nm13 + + 1], &c__[ll + c_dim1], ldc); + } + +/* Test convergence */ + + if ((r__1 = e[m - 1], dabs(r__1)) <= thresh) { + e[m - 1] = 0.f; + } + + } else { + +/* + Chase bulge from bottom to top + Save cosines and sines for later singular vector updates +*/ + + cs = 1.f; + oldcs = 1.f; + i__1 = ll + 1; + for (i__ = m; i__ >= i__1; --i__) { + r__1 = d__[i__] * cs; + slartg_(&r__1, &e[i__ - 1], &cs, &sn, &r__); + if (i__ < m) { + e[i__] = oldsn * r__; + } + r__1 = oldcs * r__; + r__2 = d__[i__ - 1] * sn; + slartg_(&r__1, &r__2, &oldcs, &oldsn, &d__[i__]); + work[i__ - ll] = cs; + work[i__ - ll + nm1] = -sn; + work[i__ - ll + nm12] = oldcs; + work[i__ - ll + nm13] = -oldsn; +/* L130: */ + } + h__ = d__[ll] * cs; + d__[ll] = h__ * oldcs; + e[ll] = h__ * oldsn; + +/* Update singular vectors */ + + if (*ncvt > 0) { + i__1 = m - ll + 1; + slasr_("L", "V", "B", &i__1, ncvt, &work[nm12 + 1], &work[ + nm13 + 1], &vt[ll + vt_dim1], ldvt); + } + if (*nru > 0) { + i__1 = m - ll + 1; + slasr_("R", "V", "B", nru, &i__1, &work[1], &work[*n], &u[ll * + u_dim1 + 1], ldu); + } + if (*ncc > 0) { + i__1 = m - ll + 1; + slasr_("L", "V", "B", &i__1, ncc, &work[1], &work[*n], &c__[ + ll + c_dim1], ldc); + } + +/* Test convergence */ + + if ((r__1 = e[ll], dabs(r__1)) <= thresh) { + e[ll] = 0.f; + } + } + } else { + +/* Use nonzero shift */ + + if (idir == 1) { + +/* + Chase bulge from top to bottom + Save cosines and sines for later singular vector updates +*/ + + f = ((r__1 = d__[ll], dabs(r__1)) - shift) * (r_sign(&c_b15, &d__[ + ll]) + shift / d__[ll]); + g = e[ll]; + i__1 = m - 1; + for (i__ = ll; i__ <= i__1; ++i__) { + slartg_(&f, &g, &cosr, &sinr, &r__); + if (i__ > ll) { + e[i__ - 1] = r__; + } + f = cosr * d__[i__] + sinr * e[i__]; + e[i__] = cosr * e[i__] - sinr * d__[i__]; + g = sinr * d__[i__ + 1]; + d__[i__ + 1] = cosr * d__[i__ + 1]; + slartg_(&f, &g, &cosl, &sinl, &r__); + d__[i__] = r__; + f = cosl * e[i__] + sinl * d__[i__ + 1]; + d__[i__ + 1] = cosl * d__[i__ + 1] - sinl * e[i__]; + if (i__ < m - 1) { + g = sinl * e[i__ + 1]; + e[i__ + 1] = cosl * e[i__ + 1]; + } + work[i__ - ll + 1] = cosr; + work[i__ - ll + 1 + nm1] = sinr; + work[i__ - ll + 1 + nm12] = cosl; + work[i__ - ll + 1 + nm13] = sinl; +/* L140: */ + } + e[m - 1] = f; + +/* Update singular vectors */ + + if (*ncvt > 0) { + i__1 = m - ll + 1; + slasr_("L", "V", "F", &i__1, ncvt, &work[1], &work[*n], &vt[ + ll + vt_dim1], ldvt); + } + if (*nru > 0) { + i__1 = m - ll + 1; + slasr_("R", "V", "F", nru, &i__1, &work[nm12 + 1], &work[nm13 + + 1], &u[ll * u_dim1 + 1], ldu); + } + if (*ncc > 0) { + i__1 = m - ll + 1; + slasr_("L", "V", "F", &i__1, ncc, &work[nm12 + 1], &work[nm13 + + 1], &c__[ll + c_dim1], ldc); + } + +/* Test convergence */ + + if ((r__1 = e[m - 1], dabs(r__1)) <= thresh) { + e[m - 1] = 0.f; + } + + } else { + +/* + Chase bulge from bottom to top + Save cosines and sines for later singular vector updates +*/ + + f = ((r__1 = d__[m], dabs(r__1)) - shift) * (r_sign(&c_b15, &d__[ + m]) + shift / d__[m]); + g = e[m - 1]; + i__1 = ll + 1; + for (i__ = m; i__ >= i__1; --i__) { + slartg_(&f, &g, &cosr, &sinr, &r__); + if (i__ < m) { + e[i__] = r__; + } + f = cosr * d__[i__] + sinr * e[i__ - 1]; + e[i__ - 1] = cosr * e[i__ - 1] - sinr * d__[i__]; + g = sinr * d__[i__ - 1]; + d__[i__ - 1] = cosr * d__[i__ - 1]; + slartg_(&f, &g, &cosl, &sinl, &r__); + d__[i__] = r__; + f = cosl * e[i__ - 1] + sinl * d__[i__ - 1]; + d__[i__ - 1] = cosl * d__[i__ - 1] - sinl * e[i__ - 1]; + if (i__ > ll + 1) { + g = sinl * e[i__ - 2]; + e[i__ - 2] = cosl * e[i__ - 2]; + } + work[i__ - ll] = cosr; + work[i__ - ll + nm1] = -sinr; + work[i__ - ll + nm12] = cosl; + work[i__ - ll + nm13] = -sinl; +/* L150: */ + } + e[ll] = f; + +/* Test convergence */ + + if ((r__1 = e[ll], dabs(r__1)) <= thresh) { + e[ll] = 0.f; + } + +/* Update singular vectors if desired */ + + if (*ncvt > 0) { + i__1 = m - ll + 1; + slasr_("L", "V", "B", &i__1, ncvt, &work[nm12 + 1], &work[ + nm13 + 1], &vt[ll + vt_dim1], ldvt); + } + if (*nru > 0) { + i__1 = m - ll + 1; + slasr_("R", "V", "B", nru, &i__1, &work[1], &work[*n], &u[ll * + u_dim1 + 1], ldu); + } + if (*ncc > 0) { + i__1 = m - ll + 1; + slasr_("L", "V", "B", &i__1, ncc, &work[1], &work[*n], &c__[ + ll + c_dim1], ldc); + } + } + } + +/* QR iteration finished, go back and check convergence */ + + goto L60; + +/* All singular values converged, so make them positive */ + +L160: + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + if (d__[i__] < 0.f) { + d__[i__] = -d__[i__]; + +/* Change sign of singular vectors, if desired */ + + if (*ncvt > 0) { + sscal_(ncvt, &c_b151, &vt[i__ + vt_dim1], ldvt); + } + } +/* L170: */ + } + +/* + Sort the singular values into decreasing order (insertion sort on + singular values, but only one transposition per singular vector) +*/ + + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + +/* Scan for smallest D(I) */ + + isub = 1; + smin = d__[1]; + i__2 = *n + 1 - i__; + for (j = 2; j <= i__2; ++j) { + if (d__[j] <= smin) { + isub = j; + smin = d__[j]; + } +/* L180: */ + } + if (isub != *n + 1 - i__) { + +/* Swap singular values and vectors */ + + d__[isub] = d__[*n + 1 - i__]; + d__[*n + 1 - i__] = smin; + if (*ncvt > 0) { + sswap_(ncvt, &vt[isub + vt_dim1], ldvt, &vt[*n + 1 - i__ + + vt_dim1], ldvt); + } + if (*nru > 0) { + sswap_(nru, &u[isub * u_dim1 + 1], &c__1, &u[(*n + 1 - i__) * + u_dim1 + 1], &c__1); + } + if (*ncc > 0) { + sswap_(ncc, &c__[isub + c_dim1], ldc, &c__[*n + 1 - i__ + + c_dim1], ldc); + } + } +/* L190: */ + } + goto L220; + +/* Maximum number of iterations exceeded, failure to converge */ + +L200: + *info = 0; + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + if (e[i__] != 0.f) { + ++(*info); + } +/* L210: */ + } +L220: + return 0; + +/* End of SBDSQR */ + +} /* sbdsqr_ */ + +/* Subroutine */ int sgebak_(char *job, char *side, integer *n, integer *ilo, + integer *ihi, real *scale, integer *m, real *v, integer *ldv, integer + *info) +{ + /* System generated locals */ + integer v_dim1, v_offset, i__1; + + /* Local variables */ + static integer i__, k; + static real s; + static integer ii; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *); + static logical leftv; + extern /* Subroutine */ int sswap_(integer *, real *, integer *, real *, + integer *), xerbla_(char *, integer *); + static logical rightv; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + September 30, 1994 + + + Purpose + ======= + + SGEBAK forms the right or left eigenvectors of a real general matrix + by backward transformation on the computed eigenvectors of the + balanced matrix output by SGEBAL. + + Arguments + ========= + + JOB (input) CHARACTER*1 + Specifies the type of backward transformation required: + = 'N', do nothing, return immediately; + = 'P', do backward transformation for permutation only; + = 'S', do backward transformation for scaling only; + = 'B', do backward transformations for both permutation and + scaling. + JOB must be the same as the argument JOB supplied to SGEBAL. + + SIDE (input) CHARACTER*1 + = 'R': V contains right eigenvectors; + = 'L': V contains left eigenvectors. + + N (input) INTEGER + The number of rows of the matrix V. N >= 0. + + ILO (input) INTEGER + IHI (input) INTEGER + The integers ILO and IHI determined by SGEBAL. + 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. + + SCALE (input) REAL array, dimension (N) + Details of the permutation and scaling factors, as returned + by SGEBAL. + + M (input) INTEGER + The number of columns of the matrix V. M >= 0. + + V (input/output) REAL array, dimension (LDV,M) + On entry, the matrix of right or left eigenvectors to be + transformed, as returned by SHSEIN or STREVC. + On exit, V is overwritten by the transformed eigenvectors. + + LDV (input) INTEGER + The leading dimension of the array V. LDV >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value. + + ===================================================================== + + + Decode and Test the input parameters +*/ + + /* Parameter adjustments */ + --scale; + v_dim1 = *ldv; + v_offset = 1 + v_dim1; + v -= v_offset; + + /* Function Body */ + rightv = lsame_(side, "R"); + leftv = lsame_(side, "L"); + + *info = 0; + if (! lsame_(job, "N") && ! lsame_(job, "P") && ! lsame_(job, "S") + && ! lsame_(job, "B")) { + *info = -1; + } else if (! rightv && ! leftv) { + *info = -2; + } else if (*n < 0) { + *info = -3; + } else if (*ilo < 1 || *ilo > max(1,*n)) { + *info = -4; + } else if (*ihi < min(*ilo,*n) || *ihi > *n) { + *info = -5; + } else if (*m < 0) { + *info = -7; + } else if (*ldv < max(1,*n)) { + *info = -9; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGEBAK", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + if (*m == 0) { + return 0; + } + if (lsame_(job, "N")) { + return 0; + } + + if (*ilo == *ihi) { + goto L30; + } + +/* Backward balance */ + + if (lsame_(job, "S") || lsame_(job, "B")) { + + if (rightv) { + i__1 = *ihi; + for (i__ = *ilo; i__ <= i__1; ++i__) { + s = scale[i__]; + sscal_(m, &s, &v[i__ + v_dim1], ldv); +/* L10: */ + } + } + + if (leftv) { + i__1 = *ihi; + for (i__ = *ilo; i__ <= i__1; ++i__) { + s = 1.f / scale[i__]; + sscal_(m, &s, &v[i__ + v_dim1], ldv); +/* L20: */ + } + } + + } + +/* + Backward permutation + + For I = ILO-1 step -1 until 1, + IHI+1 step 1 until N do -- +*/ + +L30: + if (lsame_(job, "P") || lsame_(job, "B")) { + if (rightv) { + i__1 = *n; + for (ii = 1; ii <= i__1; ++ii) { + i__ = ii; + if (i__ >= *ilo && i__ <= *ihi) { + goto L40; + } + if (i__ < *ilo) { + i__ = *ilo - ii; + } + k = scale[i__]; + if (k == i__) { + goto L40; + } + sswap_(m, &v[i__ + v_dim1], ldv, &v[k + v_dim1], ldv); +L40: + ; + } + } + + if (leftv) { + i__1 = *n; + for (ii = 1; ii <= i__1; ++ii) { + i__ = ii; + if (i__ >= *ilo && i__ <= *ihi) { + goto L50; + } + if (i__ < *ilo) { + i__ = *ilo - ii; + } + k = scale[i__]; + if (k == i__) { + goto L50; + } + sswap_(m, &v[i__ + v_dim1], ldv, &v[k + v_dim1], ldv); +L50: + ; + } + } + } + + return 0; + +/* End of SGEBAK */ + +} /* sgebak_ */ + +/* Subroutine */ int sgebal_(char *job, integer *n, real *a, integer *lda, + integer *ilo, integer *ihi, real *scale, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2; + real r__1, r__2; + + /* Local variables */ + static real c__, f, g; + static integer i__, j, k, l, m; + static real r__, s, ca, ra; + static integer ica, ira, iexc; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *), + sswap_(integer *, real *, integer *, real *, integer *); + static real sfmin1, sfmin2, sfmax1, sfmax2; + extern doublereal slamch_(char *); + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer isamax_(integer *, real *, integer *); + static logical noconv; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SGEBAL balances a general real matrix A. This involves, first, + permuting A by a similarity transformation to isolate eigenvalues + in the first 1 to ILO-1 and last IHI+1 to N elements on the + diagonal; and second, applying a diagonal similarity transformation + to rows and columns ILO to IHI to make the rows and columns as + close in norm as possible. Both steps are optional. + + Balancing may reduce the 1-norm of the matrix, and improve the + accuracy of the computed eigenvalues and/or eigenvectors. + + Arguments + ========= + + JOB (input) CHARACTER*1 + Specifies the operations to be performed on A: + = 'N': none: simply set ILO = 1, IHI = N, SCALE(I) = 1.0 + for i = 1,...,N; + = 'P': permute only; + = 'S': scale only; + = 'B': both permute and scale. + + N (input) INTEGER + The order of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the input matrix A. + On exit, A is overwritten by the balanced matrix. + If JOB = 'N', A is not referenced. + See Further Details. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + ILO (output) INTEGER + IHI (output) INTEGER + ILO and IHI are set to integers such that on exit + A(i,j) = 0 if i > j and j = 1,...,ILO-1 or I = IHI+1,...,N. + If JOB = 'N' or 'S', ILO = 1 and IHI = N. + + SCALE (output) REAL array, dimension (N) + Details of the permutations and scaling factors applied to + A. If P(j) is the index of the row and column interchanged + with row and column j and D(j) is the scaling factor + applied to row and column j, then + SCALE(j) = P(j) for j = 1,...,ILO-1 + = D(j) for j = ILO,...,IHI + = P(j) for j = IHI+1,...,N. + The order in which the interchanges are made is N to IHI+1, + then 1 to ILO-1. + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + + Further Details + =============== + + The permutations consist of row and column interchanges which put + the matrix in the form + + ( T1 X Y ) + P A P = ( 0 B Z ) + ( 0 0 T2 ) + + where T1 and T2 are upper triangular matrices whose eigenvalues lie + along the diagonal. The column indices ILO and IHI mark the starting + and ending columns of the submatrix B. Balancing consists of applying + a diagonal similarity transformation inv(D) * B * D to make the + 1-norms of each row of B and its corresponding column nearly equal. + The output matrix is + + ( T1 X*D Y ) + ( 0 inv(D)*B*D inv(D)*Z ). + ( 0 0 T2 ) + + Information about the permutations P and the diagonal matrix D is + returned in the vector SCALE. + + This subroutine is based on the EISPACK routine BALANC. + + Modified by Tzu-Yi Chen, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input parameters +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --scale; + + /* Function Body */ + *info = 0; + if (! lsame_(job, "N") && ! lsame_(job, "P") && ! lsame_(job, "S") + && ! lsame_(job, "B")) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*n)) { + *info = -4; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGEBAL", &i__1); + return 0; + } + + k = 1; + l = *n; + + if (*n == 0) { + goto L210; + } + + if (lsame_(job, "N")) { + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + scale[i__] = 1.f; +/* L10: */ + } + goto L210; + } + + if (lsame_(job, "S")) { + goto L120; + } + +/* Permutation to isolate eigenvalues if possible */ + + goto L50; + +/* Row and column exchange. */ + +L20: + scale[m] = (real) j; + if (j == m) { + goto L30; + } + + sswap_(&l, &a[j * a_dim1 + 1], &c__1, &a[m * a_dim1 + 1], &c__1); + i__1 = *n - k + 1; + sswap_(&i__1, &a[j + k * a_dim1], lda, &a[m + k * a_dim1], lda); + +L30: + switch (iexc) { + case 1: goto L40; + case 2: goto L80; + } + +/* Search for rows isolating an eigenvalue and push them down. */ + +L40: + if (l == 1) { + goto L210; + } + --l; + +L50: + for (j = l; j >= 1; --j) { + + i__1 = l; + for (i__ = 1; i__ <= i__1; ++i__) { + if (i__ == j) { + goto L60; + } + if (a[j + i__ * a_dim1] != 0.f) { + goto L70; + } +L60: + ; + } + + m = l; + iexc = 1; + goto L20; +L70: + ; + } + + goto L90; + +/* Search for columns isolating an eigenvalue and push them left. */ + +L80: + ++k; + +L90: + i__1 = l; + for (j = k; j <= i__1; ++j) { + + i__2 = l; + for (i__ = k; i__ <= i__2; ++i__) { + if (i__ == j) { + goto L100; + } + if (a[i__ + j * a_dim1] != 0.f) { + goto L110; + } +L100: + ; + } + + m = k; + iexc = 2; + goto L20; +L110: + ; + } + +L120: + i__1 = l; + for (i__ = k; i__ <= i__1; ++i__) { + scale[i__] = 1.f; +/* L130: */ + } + + if (lsame_(job, "P")) { + goto L210; + } + +/* + Balance the submatrix in rows K to L. + + Iterative loop for norm reduction +*/ + + sfmin1 = slamch_("S") / slamch_("P"); + sfmax1 = 1.f / sfmin1; + sfmin2 = sfmin1 * 8.f; + sfmax2 = 1.f / sfmin2; +L140: + noconv = FALSE_; + + i__1 = l; + for (i__ = k; i__ <= i__1; ++i__) { + c__ = 0.f; + r__ = 0.f; + + i__2 = l; + for (j = k; j <= i__2; ++j) { + if (j == i__) { + goto L150; + } + c__ += (r__1 = a[j + i__ * a_dim1], dabs(r__1)); + r__ += (r__1 = a[i__ + j * a_dim1], dabs(r__1)); +L150: + ; + } + ica = isamax_(&l, &a[i__ * a_dim1 + 1], &c__1); + ca = (r__1 = a[ica + i__ * a_dim1], dabs(r__1)); + i__2 = *n - k + 1; + ira = isamax_(&i__2, &a[i__ + k * a_dim1], lda); + ra = (r__1 = a[i__ + (ira + k - 1) * a_dim1], dabs(r__1)); + +/* Guard against zero C or R due to underflow. */ + + if (c__ == 0.f || r__ == 0.f) { + goto L200; + } + g = r__ / 8.f; + f = 1.f; + s = c__ + r__; +L160: +/* Computing MAX */ + r__1 = max(f,c__); +/* Computing MIN */ + r__2 = min(r__,g); + if (c__ >= g || dmax(r__1,ca) >= sfmax2 || dmin(r__2,ra) <= sfmin2) { + goto L170; + } + f *= 8.f; + c__ *= 8.f; + ca *= 8.f; + r__ /= 8.f; + g /= 8.f; + ra /= 8.f; + goto L160; + +L170: + g = c__ / 8.f; +L180: +/* Computing MIN */ + r__1 = min(f,c__), r__1 = min(r__1,g); + if (g < r__ || dmax(r__,ra) >= sfmax2 || dmin(r__1,ca) <= sfmin2) { + goto L190; + } + f /= 8.f; + c__ /= 8.f; + g /= 8.f; + ca /= 8.f; + r__ *= 8.f; + ra *= 8.f; + goto L180; + +/* Now balance. */ + +L190: + if (c__ + r__ >= s * .95f) { + goto L200; + } + if (f < 1.f && scale[i__] < 1.f) { + if (f * scale[i__] <= sfmin1) { + goto L200; + } + } + if (f > 1.f && scale[i__] > 1.f) { + if (scale[i__] >= sfmax1 / f) { + goto L200; + } + } + g = 1.f / f; + scale[i__] *= f; + noconv = TRUE_; + + i__2 = *n - k + 1; + sscal_(&i__2, &g, &a[i__ + k * a_dim1], lda); + sscal_(&l, &f, &a[i__ * a_dim1 + 1], &c__1); + +L200: + ; + } + + if (noconv) { + goto L140; + } + +L210: + *ilo = k; + *ihi = l; + + return 0; + +/* End of SGEBAL */ + +} /* sgebal_ */ + +/* Subroutine */ int sgebd2_(integer *m, integer *n, real *a, integer *lda, + real *d__, real *e, real *tauq, real *taup, real *work, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3, i__4; + + /* Local variables */ + static integer i__; + extern /* Subroutine */ int slarf_(char *, integer *, integer *, real *, + integer *, real *, real *, integer *, real *), xerbla_( + char *, integer *), slarfg_(integer *, real *, real *, + integer *, real *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SGEBD2 reduces a real general m by n matrix A to upper or lower + bidiagonal form B by an orthogonal transformation: Q' * A * P = B. + + If m >= n, B is upper bidiagonal; if m < n, B is lower bidiagonal. + + Arguments + ========= + + M (input) INTEGER + The number of rows in the matrix A. M >= 0. + + N (input) INTEGER + The number of columns in the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the m by n general matrix to be reduced. + On exit, + if m >= n, the diagonal and the first superdiagonal are + overwritten with the upper bidiagonal matrix B; the + elements below the diagonal, with the array TAUQ, represent + the orthogonal matrix Q as a product of elementary + reflectors, and the elements above the first superdiagonal, + with the array TAUP, represent the orthogonal matrix P as + a product of elementary reflectors; + if m < n, the diagonal and the first subdiagonal are + overwritten with the lower bidiagonal matrix B; the + elements below the first subdiagonal, with the array TAUQ, + represent the orthogonal matrix Q as a product of + elementary reflectors, and the elements above the diagonal, + with the array TAUP, represent the orthogonal matrix P as + a product of elementary reflectors. + See Further Details. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + D (output) REAL array, dimension (min(M,N)) + The diagonal elements of the bidiagonal matrix B: + D(i) = A(i,i). + + E (output) REAL array, dimension (min(M,N)-1) + The off-diagonal elements of the bidiagonal matrix B: + if m >= n, E(i) = A(i,i+1) for i = 1,2,...,n-1; + if m < n, E(i) = A(i+1,i) for i = 1,2,...,m-1. + + TAUQ (output) REAL array dimension (min(M,N)) + The scalar factors of the elementary reflectors which + represent the orthogonal matrix Q. See Further Details. + + TAUP (output) REAL array, dimension (min(M,N)) + The scalar factors of the elementary reflectors which + represent the orthogonal matrix P. See Further Details. + + WORK (workspace) REAL array, dimension (max(M,N)) + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + + Further Details + =============== + + The matrices Q and P are represented as products of elementary + reflectors: + + If m >= n, + + Q = H(1) H(2) . . . H(n) and P = G(1) G(2) . . . G(n-1) + + Each H(i) and G(i) has the form: + + H(i) = I - tauq * v * v' and G(i) = I - taup * u * u' + + where tauq and taup are real scalars, and v and u are real vectors; + v(1:i-1) = 0, v(i) = 1, and v(i+1:m) is stored on exit in A(i+1:m,i); + u(1:i) = 0, u(i+1) = 1, and u(i+2:n) is stored on exit in A(i,i+2:n); + tauq is stored in TAUQ(i) and taup in TAUP(i). + + If m < n, + + Q = H(1) H(2) . . . H(m-1) and P = G(1) G(2) . . . G(m) + + Each H(i) and G(i) has the form: + + H(i) = I - tauq * v * v' and G(i) = I - taup * u * u' + + where tauq and taup are real scalars, and v and u are real vectors; + v(1:i) = 0, v(i+1) = 1, and v(i+2:m) is stored on exit in A(i+2:m,i); + u(1:i-1) = 0, u(i) = 1, and u(i+1:n) is stored on exit in A(i,i+1:n); + tauq is stored in TAUQ(i) and taup in TAUP(i). + + The contents of A on exit are illustrated by the following examples: + + m = 6 and n = 5 (m > n): m = 5 and n = 6 (m < n): + + ( d e u1 u1 u1 ) ( d u1 u1 u1 u1 u1 ) + ( v1 d e u2 u2 ) ( e d u2 u2 u2 u2 ) + ( v1 v2 d e u3 ) ( v1 e d u3 u3 u3 ) + ( v1 v2 v3 d e ) ( v1 v2 e d u4 u4 ) + ( v1 v2 v3 v4 d ) ( v1 v2 v3 e d u5 ) + ( v1 v2 v3 v4 v5 ) + + where d and e denote diagonal and off-diagonal elements of B, vi + denotes an element of the vector defining H(i), and ui an element of + the vector defining G(i). + + ===================================================================== + + + Test the input parameters +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --d__; + --e; + --tauq; + --taup; + --work; + + /* Function Body */ + *info = 0; + if (*m < 0) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*m)) { + *info = -4; + } + if (*info < 0) { + i__1 = -(*info); + xerbla_("SGEBD2", &i__1); + return 0; + } + + if (*m >= *n) { + +/* Reduce to upper bidiagonal form */ + + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + +/* Generate elementary reflector H(i) to annihilate A(i+1:m,i) */ + + i__2 = *m - i__ + 1; +/* Computing MIN */ + i__3 = i__ + 1; + slarfg_(&i__2, &a[i__ + i__ * a_dim1], &a[min(i__3,*m) + i__ * + a_dim1], &c__1, &tauq[i__]); + d__[i__] = a[i__ + i__ * a_dim1]; + a[i__ + i__ * a_dim1] = 1.f; + +/* Apply H(i) to A(i:m,i+1:n) from the left */ + + i__2 = *m - i__ + 1; + i__3 = *n - i__; + slarf_("Left", &i__2, &i__3, &a[i__ + i__ * a_dim1], &c__1, &tauq[ + i__], &a[i__ + (i__ + 1) * a_dim1], lda, &work[1]); + a[i__ + i__ * a_dim1] = d__[i__]; + + if (i__ < *n) { + +/* + Generate elementary reflector G(i) to annihilate + A(i,i+2:n) +*/ + + i__2 = *n - i__; +/* Computing MIN */ + i__3 = i__ + 2; + slarfg_(&i__2, &a[i__ + (i__ + 1) * a_dim1], &a[i__ + min( + i__3,*n) * a_dim1], lda, &taup[i__]); + e[i__] = a[i__ + (i__ + 1) * a_dim1]; + a[i__ + (i__ + 1) * a_dim1] = 1.f; + +/* Apply G(i) to A(i+1:m,i+1:n) from the right */ + + i__2 = *m - i__; + i__3 = *n - i__; + slarf_("Right", &i__2, &i__3, &a[i__ + (i__ + 1) * a_dim1], + lda, &taup[i__], &a[i__ + 1 + (i__ + 1) * a_dim1], + lda, &work[1]); + a[i__ + (i__ + 1) * a_dim1] = e[i__]; + } else { + taup[i__] = 0.f; + } +/* L10: */ + } + } else { + +/* Reduce to lower bidiagonal form */ + + i__1 = *m; + for (i__ = 1; i__ <= i__1; ++i__) { + +/* Generate elementary reflector G(i) to annihilate A(i,i+1:n) */ + + i__2 = *n - i__ + 1; +/* Computing MIN */ + i__3 = i__ + 1; + slarfg_(&i__2, &a[i__ + i__ * a_dim1], &a[i__ + min(i__3,*n) * + a_dim1], lda, &taup[i__]); + d__[i__] = a[i__ + i__ * a_dim1]; + a[i__ + i__ * a_dim1] = 1.f; + +/* Apply G(i) to A(i+1:m,i:n) from the right */ + + i__2 = *m - i__; + i__3 = *n - i__ + 1; +/* Computing MIN */ + i__4 = i__ + 1; + slarf_("Right", &i__2, &i__3, &a[i__ + i__ * a_dim1], lda, &taup[ + i__], &a[min(i__4,*m) + i__ * a_dim1], lda, &work[1]); + a[i__ + i__ * a_dim1] = d__[i__]; + + if (i__ < *m) { + +/* + Generate elementary reflector H(i) to annihilate + A(i+2:m,i) +*/ + + i__2 = *m - i__; +/* Computing MIN */ + i__3 = i__ + 2; + slarfg_(&i__2, &a[i__ + 1 + i__ * a_dim1], &a[min(i__3,*m) + + i__ * a_dim1], &c__1, &tauq[i__]); + e[i__] = a[i__ + 1 + i__ * a_dim1]; + a[i__ + 1 + i__ * a_dim1] = 1.f; + +/* Apply H(i) to A(i+1:m,i+1:n) from the left */ + + i__2 = *m - i__; + i__3 = *n - i__; + slarf_("Left", &i__2, &i__3, &a[i__ + 1 + i__ * a_dim1], & + c__1, &tauq[i__], &a[i__ + 1 + (i__ + 1) * a_dim1], + lda, &work[1]); + a[i__ + 1 + i__ * a_dim1] = e[i__]; + } else { + tauq[i__] = 0.f; + } +/* L20: */ + } + } + return 0; + +/* End of SGEBD2 */ + +} /* sgebd2_ */ + +/* Subroutine */ int sgebrd_(integer *m, integer *n, real *a, integer *lda, + real *d__, real *e, real *tauq, real *taup, real *work, integer * + lwork, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3, i__4; + + /* Local variables */ + static integer i__, j, nb, nx; + static real ws; + static integer nbmin, iinfo; + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *); + static integer minmn; + extern /* Subroutine */ int sgebd2_(integer *, integer *, real *, integer + *, real *, real *, real *, real *, real *, integer *), slabrd_( + integer *, integer *, integer *, real *, integer *, real *, real * + , real *, real *, real *, integer *, real *, integer *), xerbla_( + char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + static integer ldwrkx, ldwrky, lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SGEBRD reduces a general real M-by-N matrix A to upper or lower + bidiagonal form B by an orthogonal transformation: Q**T * A * P = B. + + If m >= n, B is upper bidiagonal; if m < n, B is lower bidiagonal. + + Arguments + ========= + + M (input) INTEGER + The number of rows in the matrix A. M >= 0. + + N (input) INTEGER + The number of columns in the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the M-by-N general matrix to be reduced. + On exit, + if m >= n, the diagonal and the first superdiagonal are + overwritten with the upper bidiagonal matrix B; the + elements below the diagonal, with the array TAUQ, represent + the orthogonal matrix Q as a product of elementary + reflectors, and the elements above the first superdiagonal, + with the array TAUP, represent the orthogonal matrix P as + a product of elementary reflectors; + if m < n, the diagonal and the first subdiagonal are + overwritten with the lower bidiagonal matrix B; the + elements below the first subdiagonal, with the array TAUQ, + represent the orthogonal matrix Q as a product of + elementary reflectors, and the elements above the diagonal, + with the array TAUP, represent the orthogonal matrix P as + a product of elementary reflectors. + See Further Details. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + D (output) REAL array, dimension (min(M,N)) + The diagonal elements of the bidiagonal matrix B: + D(i) = A(i,i). + + E (output) REAL array, dimension (min(M,N)-1) + The off-diagonal elements of the bidiagonal matrix B: + if m >= n, E(i) = A(i,i+1) for i = 1,2,...,n-1; + if m < n, E(i) = A(i+1,i) for i = 1,2,...,m-1. + + TAUQ (output) REAL array dimension (min(M,N)) + The scalar factors of the elementary reflectors which + represent the orthogonal matrix Q. See Further Details. + + TAUP (output) REAL array, dimension (min(M,N)) + The scalar factors of the elementary reflectors which + represent the orthogonal matrix P. See Further Details. + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The length of the array WORK. LWORK >= max(1,M,N). + For optimum performance LWORK >= (M+N)*NB, where NB + is the optimal blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value. + + Further Details + =============== + + The matrices Q and P are represented as products of elementary + reflectors: + + If m >= n, + + Q = H(1) H(2) . . . H(n) and P = G(1) G(2) . . . G(n-1) + + Each H(i) and G(i) has the form: + + H(i) = I - tauq * v * v' and G(i) = I - taup * u * u' + + where tauq and taup are real scalars, and v and u are real vectors; + v(1:i-1) = 0, v(i) = 1, and v(i+1:m) is stored on exit in A(i+1:m,i); + u(1:i) = 0, u(i+1) = 1, and u(i+2:n) is stored on exit in A(i,i+2:n); + tauq is stored in TAUQ(i) and taup in TAUP(i). + + If m < n, + + Q = H(1) H(2) . . . H(m-1) and P = G(1) G(2) . . . G(m) + + Each H(i) and G(i) has the form: + + H(i) = I - tauq * v * v' and G(i) = I - taup * u * u' + + where tauq and taup are real scalars, and v and u are real vectors; + v(1:i) = 0, v(i+1) = 1, and v(i+2:m) is stored on exit in A(i+2:m,i); + u(1:i-1) = 0, u(i) = 1, and u(i+1:n) is stored on exit in A(i,i+1:n); + tauq is stored in TAUQ(i) and taup in TAUP(i). + + The contents of A on exit are illustrated by the following examples: + + m = 6 and n = 5 (m > n): m = 5 and n = 6 (m < n): + + ( d e u1 u1 u1 ) ( d u1 u1 u1 u1 u1 ) + ( v1 d e u2 u2 ) ( e d u2 u2 u2 u2 ) + ( v1 v2 d e u3 ) ( v1 e d u3 u3 u3 ) + ( v1 v2 v3 d e ) ( v1 v2 e d u4 u4 ) + ( v1 v2 v3 v4 d ) ( v1 v2 v3 e d u5 ) + ( v1 v2 v3 v4 v5 ) + + where d and e denote diagonal and off-diagonal elements of B, vi + denotes an element of the vector defining H(i), and ui an element of + the vector defining G(i). + + ===================================================================== + + + Test the input parameters +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --d__; + --e; + --tauq; + --taup; + --work; + + /* Function Body */ + *info = 0; +/* Computing MAX */ + i__1 = 1, i__2 = ilaenv_(&c__1, "SGEBRD", " ", m, n, &c_n1, &c_n1, ( + ftnlen)6, (ftnlen)1); + nb = max(i__1,i__2); + lwkopt = (*m + *n) * nb; + work[1] = (real) lwkopt; + lquery = *lwork == -1; + if (*m < 0) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*m)) { + *info = -4; + } else /* if(complicated condition) */ { +/* Computing MAX */ + i__1 = max(1,*m); + if (*lwork < max(i__1,*n) && ! lquery) { + *info = -10; + } + } + if (*info < 0) { + i__1 = -(*info); + xerbla_("SGEBRD", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + minmn = min(*m,*n); + if (minmn == 0) { + work[1] = 1.f; + return 0; + } + + ws = (real) max(*m,*n); + ldwrkx = *m; + ldwrky = *n; + + if (nb > 1 && nb < minmn) { + +/* + Set the crossover point NX. + + Computing MAX +*/ + i__1 = nb, i__2 = ilaenv_(&c__3, "SGEBRD", " ", m, n, &c_n1, &c_n1, ( + ftnlen)6, (ftnlen)1); + nx = max(i__1,i__2); + +/* Determine when to switch from blocked to unblocked code. */ + + if (nx < minmn) { + ws = (real) ((*m + *n) * nb); + if ((real) (*lwork) < ws) { + +/* + Not enough work space for the optimal NB, consider using + a smaller block size. +*/ + + nbmin = ilaenv_(&c__2, "SGEBRD", " ", m, n, &c_n1, &c_n1, ( + ftnlen)6, (ftnlen)1); + if (*lwork >= (*m + *n) * nbmin) { + nb = *lwork / (*m + *n); + } else { + nb = 1; + nx = minmn; + } + } + } + } else { + nx = minmn; + } + + i__1 = minmn - nx; + i__2 = nb; + for (i__ = 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { + +/* + Reduce rows and columns i:i+nb-1 to bidiagonal form and return + the matrices X and Y which are needed to update the unreduced + part of the matrix +*/ + + i__3 = *m - i__ + 1; + i__4 = *n - i__ + 1; + slabrd_(&i__3, &i__4, &nb, &a[i__ + i__ * a_dim1], lda, &d__[i__], &e[ + i__], &tauq[i__], &taup[i__], &work[1], &ldwrkx, &work[ldwrkx + * nb + 1], &ldwrky); + +/* + Update the trailing submatrix A(i+nb:m,i+nb:n), using an update + of the form A := A - V*Y' - X*U' +*/ + + i__3 = *m - i__ - nb + 1; + i__4 = *n - i__ - nb + 1; + sgemm_("No transpose", "Transpose", &i__3, &i__4, &nb, &c_b151, &a[ + i__ + nb + i__ * a_dim1], lda, &work[ldwrkx * nb + nb + 1], & + ldwrky, &c_b15, &a[i__ + nb + (i__ + nb) * a_dim1], lda); + i__3 = *m - i__ - nb + 1; + i__4 = *n - i__ - nb + 1; + sgemm_("No transpose", "No transpose", &i__3, &i__4, &nb, &c_b151, & + work[nb + 1], &ldwrkx, &a[i__ + (i__ + nb) * a_dim1], lda, & + c_b15, &a[i__ + nb + (i__ + nb) * a_dim1], lda); + +/* Copy diagonal and off-diagonal elements of B back into A */ + + if (*m >= *n) { + i__3 = i__ + nb - 1; + for (j = i__; j <= i__3; ++j) { + a[j + j * a_dim1] = d__[j]; + a[j + (j + 1) * a_dim1] = e[j]; +/* L10: */ + } + } else { + i__3 = i__ + nb - 1; + for (j = i__; j <= i__3; ++j) { + a[j + j * a_dim1] = d__[j]; + a[j + 1 + j * a_dim1] = e[j]; +/* L20: */ + } + } +/* L30: */ + } + +/* Use unblocked code to reduce the remainder of the matrix */ + + i__2 = *m - i__ + 1; + i__1 = *n - i__ + 1; + sgebd2_(&i__2, &i__1, &a[i__ + i__ * a_dim1], lda, &d__[i__], &e[i__], & + tauq[i__], &taup[i__], &work[1], &iinfo); + work[1] = ws; + return 0; + +/* End of SGEBRD */ + +} /* sgebrd_ */ + +/* Subroutine */ int sgeev_(char *jobvl, char *jobvr, integer *n, real *a, + integer *lda, real *wr, real *wi, real *vl, integer *ldvl, real *vr, + integer *ldvr, real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, vl_dim1, vl_offset, vr_dim1, vr_offset, i__1, + i__2, i__3, i__4; + real r__1, r__2; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static integer i__, k; + static real r__, cs, sn; + static integer ihi; + static real scl; + static integer ilo; + static real dum[1], eps; + static integer ibal; + static char side[1]; + static integer maxb; + static real anrm; + static integer ierr, itau, iwrk, nout; + extern /* Subroutine */ int srot_(integer *, real *, integer *, real *, + integer *, real *, real *); + extern doublereal snrm2_(integer *, real *, integer *); + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *); + extern doublereal slapy2_(real *, real *); + extern /* Subroutine */ int slabad_(real *, real *); + static logical scalea; + static real cscale; + extern /* Subroutine */ int sgebak_(char *, char *, integer *, integer *, + integer *, real *, integer *, real *, integer *, integer *), sgebal_(char *, integer *, real *, integer *, + integer *, integer *, real *, integer *); + extern doublereal slamch_(char *), slange_(char *, integer *, + integer *, real *, integer *, real *); + extern /* Subroutine */ int sgehrd_(integer *, integer *, integer *, real + *, integer *, real *, real *, integer *, integer *), xerbla_(char + *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + static logical select[1]; + static real bignum; + extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *, + real *, integer *, integer *, real *, integer *, integer *); + extern integer isamax_(integer *, real *, integer *); + extern /* Subroutine */ int slacpy_(char *, integer *, integer *, real *, + integer *, real *, integer *), slartg_(real *, real *, + real *, real *, real *), sorghr_(integer *, integer *, integer *, + real *, integer *, real *, real *, integer *, integer *), shseqr_( + char *, char *, integer *, integer *, integer *, real *, integer * + , real *, real *, real *, integer *, real *, integer *, integer *), strevc_(char *, char *, logical *, integer *, + real *, integer *, real *, integer *, real *, integer *, integer * + , integer *, real *, integer *); + static integer minwrk, maxwrk; + static logical wantvl; + static real smlnum; + static integer hswork; + static logical lquery, wantvr; + + +/* + -- LAPACK driver routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + December 8, 1999 + + + Purpose + ======= + + SGEEV computes for an N-by-N real nonsymmetric matrix A, the + eigenvalues and, optionally, the left and/or right eigenvectors. + + The right eigenvector v(j) of A satisfies + A * v(j) = lambda(j) * v(j) + where lambda(j) is its eigenvalue. + The left eigenvector u(j) of A satisfies + u(j)**H * A = lambda(j) * u(j)**H + where u(j)**H denotes the conjugate transpose of u(j). + + The computed eigenvectors are normalized to have Euclidean norm + equal to 1 and largest component real. + + Arguments + ========= + + JOBVL (input) CHARACTER*1 + = 'N': left eigenvectors of A are not computed; + = 'V': left eigenvectors of A are computed. + + JOBVR (input) CHARACTER*1 + = 'N': right eigenvectors of A are not computed; + = 'V': right eigenvectors of A are computed. + + N (input) INTEGER + The order of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the N-by-N matrix A. + On exit, A has been overwritten. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + WR (output) REAL array, dimension (N) + WI (output) REAL array, dimension (N) + WR and WI contain the real and imaginary parts, + respectively, of the computed eigenvalues. Complex + conjugate pairs of eigenvalues appear consecutively + with the eigenvalue having the positive imaginary part + first. + + VL (output) REAL array, dimension (LDVL,N) + If JOBVL = 'V', the left eigenvectors u(j) are stored one + after another in the columns of VL, in the same order + as their eigenvalues. + If JOBVL = 'N', VL is not referenced. + If the j-th eigenvalue is real, then u(j) = VL(:,j), + the j-th column of VL. + If the j-th and (j+1)-st eigenvalues form a complex + conjugate pair, then u(j) = VL(:,j) + i*VL(:,j+1) and + u(j+1) = VL(:,j) - i*VL(:,j+1). + + LDVL (input) INTEGER + The leading dimension of the array VL. LDVL >= 1; if + JOBVL = 'V', LDVL >= N. + + VR (output) REAL array, dimension (LDVR,N) + If JOBVR = 'V', the right eigenvectors v(j) are stored one + after another in the columns of VR, in the same order + as their eigenvalues. + If JOBVR = 'N', VR is not referenced. + If the j-th eigenvalue is real, then v(j) = VR(:,j), + the j-th column of VR. + If the j-th and (j+1)-st eigenvalues form a complex + conjugate pair, then v(j) = VR(:,j) + i*VR(:,j+1) and + v(j+1) = VR(:,j) - i*VR(:,j+1). + + LDVR (input) INTEGER + The leading dimension of the array VR. LDVR >= 1; if + JOBVR = 'V', LDVR >= N. + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. LWORK >= max(1,3*N), and + if JOBVL = 'V' or JOBVR = 'V', LWORK >= 4*N. For good + performance, LWORK must generally be larger. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: if INFO = i, the QR algorithm failed to compute all the + eigenvalues, and no eigenvectors have been computed; + elements i+1:N of WR and WI contain eigenvalues which + have converged. + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --wr; + --wi; + vl_dim1 = *ldvl; + vl_offset = 1 + vl_dim1; + vl -= vl_offset; + vr_dim1 = *ldvr; + vr_offset = 1 + vr_dim1; + vr -= vr_offset; + --work; + + /* Function Body */ + *info = 0; + lquery = *lwork == -1; + wantvl = lsame_(jobvl, "V"); + wantvr = lsame_(jobvr, "V"); + if (! wantvl && ! lsame_(jobvl, "N")) { + *info = -1; + } else if (! wantvr && ! lsame_(jobvr, "N")) { + *info = -2; + } else if (*n < 0) { + *info = -3; + } else if (*lda < max(1,*n)) { + *info = -5; + } else if (*ldvl < 1 || wantvl && *ldvl < *n) { + *info = -9; + } else if (*ldvr < 1 || wantvr && *ldvr < *n) { + *info = -11; + } + +/* + Compute workspace + (Note: Comments in the code beginning "Workspace:" describe the + minimal amount of workspace needed at that point in the code, + as well as the preferred amount for good performance. + NB refers to the optimal block size for the immediately + following subroutine, as returned by ILAENV. + HSWORK refers to the workspace preferred by SHSEQR, as + calculated below. HSWORK is computed assuming ILO=1 and IHI=N, + the worst case.) +*/ + + minwrk = 1; + if (*info == 0 && (*lwork >= 1 || lquery)) { + maxwrk = (*n << 1) + *n * ilaenv_(&c__1, "SGEHRD", " ", n, &c__1, n, & + c__0, (ftnlen)6, (ftnlen)1); + if (! wantvl && ! wantvr) { +/* Computing MAX */ + i__1 = 1, i__2 = *n * 3; + minwrk = max(i__1,i__2); +/* Computing MAX */ + i__1 = ilaenv_(&c__8, "SHSEQR", "EN", n, &c__1, n, &c_n1, (ftnlen) + 6, (ftnlen)2); + maxb = max(i__1,2); +/* + Computing MIN + Computing MAX +*/ + i__3 = 2, i__4 = ilaenv_(&c__4, "SHSEQR", "EN", n, &c__1, n, & + c_n1, (ftnlen)6, (ftnlen)2); + i__1 = min(maxb,*n), i__2 = max(i__3,i__4); + k = min(i__1,i__2); +/* Computing MAX */ + i__1 = k * (k + 2), i__2 = *n << 1; + hswork = max(i__1,i__2); +/* Computing MAX */ + i__1 = maxwrk, i__2 = *n + 1, i__1 = max(i__1,i__2), i__2 = *n + + hswork; + maxwrk = max(i__1,i__2); + } else { +/* Computing MAX */ + i__1 = 1, i__2 = *n << 2; + minwrk = max(i__1,i__2); +/* Computing MAX */ + i__1 = maxwrk, i__2 = (*n << 1) + (*n - 1) * ilaenv_(&c__1, "SOR" + "GHR", " ", n, &c__1, n, &c_n1, (ftnlen)6, (ftnlen)1); + maxwrk = max(i__1,i__2); +/* Computing MAX */ + i__1 = ilaenv_(&c__8, "SHSEQR", "SV", n, &c__1, n, &c_n1, (ftnlen) + 6, (ftnlen)2); + maxb = max(i__1,2); +/* + Computing MIN + Computing MAX +*/ + i__3 = 2, i__4 = ilaenv_(&c__4, "SHSEQR", "SV", n, &c__1, n, & + c_n1, (ftnlen)6, (ftnlen)2); + i__1 = min(maxb,*n), i__2 = max(i__3,i__4); + k = min(i__1,i__2); +/* Computing MAX */ + i__1 = k * (k + 2), i__2 = *n << 1; + hswork = max(i__1,i__2); +/* Computing MAX */ + i__1 = maxwrk, i__2 = *n + 1, i__1 = max(i__1,i__2), i__2 = *n + + hswork; + maxwrk = max(i__1,i__2); +/* Computing MAX */ + i__1 = maxwrk, i__2 = *n << 2; + maxwrk = max(i__1,i__2); + } + work[1] = (real) maxwrk; + } + if (*lwork < minwrk && ! lquery) { + *info = -13; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGEEV ", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + +/* Get machine constants */ + + eps = slamch_("P"); + smlnum = slamch_("S"); + bignum = 1.f / smlnum; + slabad_(&smlnum, &bignum); + smlnum = sqrt(smlnum) / eps; + bignum = 1.f / smlnum; + +/* Scale A if max element outside range [SMLNUM,BIGNUM] */ + + anrm = slange_("M", n, n, &a[a_offset], lda, dum); + scalea = FALSE_; + if (anrm > 0.f && anrm < smlnum) { + scalea = TRUE_; + cscale = smlnum; + } else if (anrm > bignum) { + scalea = TRUE_; + cscale = bignum; + } + if (scalea) { + slascl_("G", &c__0, &c__0, &anrm, &cscale, n, n, &a[a_offset], lda, & + ierr); + } + +/* + Balance the matrix + (Workspace: need N) +*/ + + ibal = 1; + sgebal_("B", n, &a[a_offset], lda, &ilo, &ihi, &work[ibal], &ierr); + +/* + Reduce to upper Hessenberg form + (Workspace: need 3*N, prefer 2*N+N*NB) +*/ + + itau = ibal + *n; + iwrk = itau + *n; + i__1 = *lwork - iwrk + 1; + sgehrd_(n, &ilo, &ihi, &a[a_offset], lda, &work[itau], &work[iwrk], &i__1, + &ierr); + + if (wantvl) { + +/* + Want left eigenvectors + Copy Householder vectors to VL +*/ + + *(unsigned char *)side = 'L'; + slacpy_("L", n, n, &a[a_offset], lda, &vl[vl_offset], ldvl) + ; + +/* + Generate orthogonal matrix in VL + (Workspace: need 3*N-1, prefer 2*N+(N-1)*NB) +*/ + + i__1 = *lwork - iwrk + 1; + sorghr_(n, &ilo, &ihi, &vl[vl_offset], ldvl, &work[itau], &work[iwrk], + &i__1, &ierr); + +/* + Perform QR iteration, accumulating Schur vectors in VL + (Workspace: need N+1, prefer N+HSWORK (see comments) ) +*/ + + iwrk = itau; + i__1 = *lwork - iwrk + 1; + shseqr_("S", "V", n, &ilo, &ihi, &a[a_offset], lda, &wr[1], &wi[1], & + vl[vl_offset], ldvl, &work[iwrk], &i__1, info); + + if (wantvr) { + +/* + Want left and right eigenvectors + Copy Schur vectors to VR +*/ + + *(unsigned char *)side = 'B'; + slacpy_("F", n, n, &vl[vl_offset], ldvl, &vr[vr_offset], ldvr); + } + + } else if (wantvr) { + +/* + Want right eigenvectors + Copy Householder vectors to VR +*/ + + *(unsigned char *)side = 'R'; + slacpy_("L", n, n, &a[a_offset], lda, &vr[vr_offset], ldvr) + ; + +/* + Generate orthogonal matrix in VR + (Workspace: need 3*N-1, prefer 2*N+(N-1)*NB) +*/ + + i__1 = *lwork - iwrk + 1; + sorghr_(n, &ilo, &ihi, &vr[vr_offset], ldvr, &work[itau], &work[iwrk], + &i__1, &ierr); + +/* + Perform QR iteration, accumulating Schur vectors in VR + (Workspace: need N+1, prefer N+HSWORK (see comments) ) +*/ + + iwrk = itau; + i__1 = *lwork - iwrk + 1; + shseqr_("S", "V", n, &ilo, &ihi, &a[a_offset], lda, &wr[1], &wi[1], & + vr[vr_offset], ldvr, &work[iwrk], &i__1, info); + + } else { + +/* + Compute eigenvalues only + (Workspace: need N+1, prefer N+HSWORK (see comments) ) +*/ + + iwrk = itau; + i__1 = *lwork - iwrk + 1; + shseqr_("E", "N", n, &ilo, &ihi, &a[a_offset], lda, &wr[1], &wi[1], & + vr[vr_offset], ldvr, &work[iwrk], &i__1, info); + } + +/* If INFO > 0 from SHSEQR, then quit */ + + if (*info > 0) { + goto L50; + } + + if (wantvl || wantvr) { + +/* + Compute left and/or right eigenvectors + (Workspace: need 4*N) +*/ + + strevc_(side, "B", select, n, &a[a_offset], lda, &vl[vl_offset], ldvl, + &vr[vr_offset], ldvr, n, &nout, &work[iwrk], &ierr); + } + + if (wantvl) { + +/* + Undo balancing of left eigenvectors + (Workspace: need N) +*/ + + sgebak_("B", "L", n, &ilo, &ihi, &work[ibal], n, &vl[vl_offset], ldvl, + &ierr); + +/* Normalize left eigenvectors and make largest component real */ + + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + if (wi[i__] == 0.f) { + scl = 1.f / snrm2_(n, &vl[i__ * vl_dim1 + 1], &c__1); + sscal_(n, &scl, &vl[i__ * vl_dim1 + 1], &c__1); + } else if (wi[i__] > 0.f) { + r__1 = snrm2_(n, &vl[i__ * vl_dim1 + 1], &c__1); + r__2 = snrm2_(n, &vl[(i__ + 1) * vl_dim1 + 1], &c__1); + scl = 1.f / slapy2_(&r__1, &r__2); + sscal_(n, &scl, &vl[i__ * vl_dim1 + 1], &c__1); + sscal_(n, &scl, &vl[(i__ + 1) * vl_dim1 + 1], &c__1); + i__2 = *n; + for (k = 1; k <= i__2; ++k) { +/* Computing 2nd power */ + r__1 = vl[k + i__ * vl_dim1]; +/* Computing 2nd power */ + r__2 = vl[k + (i__ + 1) * vl_dim1]; + work[iwrk + k - 1] = r__1 * r__1 + r__2 * r__2; +/* L10: */ + } + k = isamax_(n, &work[iwrk], &c__1); + slartg_(&vl[k + i__ * vl_dim1], &vl[k + (i__ + 1) * vl_dim1], + &cs, &sn, &r__); + srot_(n, &vl[i__ * vl_dim1 + 1], &c__1, &vl[(i__ + 1) * + vl_dim1 + 1], &c__1, &cs, &sn); + vl[k + (i__ + 1) * vl_dim1] = 0.f; + } +/* L20: */ + } + } + + if (wantvr) { + +/* + Undo balancing of right eigenvectors + (Workspace: need N) +*/ + + sgebak_("B", "R", n, &ilo, &ihi, &work[ibal], n, &vr[vr_offset], ldvr, + &ierr); + +/* Normalize right eigenvectors and make largest component real */ + + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + if (wi[i__] == 0.f) { + scl = 1.f / snrm2_(n, &vr[i__ * vr_dim1 + 1], &c__1); + sscal_(n, &scl, &vr[i__ * vr_dim1 + 1], &c__1); + } else if (wi[i__] > 0.f) { + r__1 = snrm2_(n, &vr[i__ * vr_dim1 + 1], &c__1); + r__2 = snrm2_(n, &vr[(i__ + 1) * vr_dim1 + 1], &c__1); + scl = 1.f / slapy2_(&r__1, &r__2); + sscal_(n, &scl, &vr[i__ * vr_dim1 + 1], &c__1); + sscal_(n, &scl, &vr[(i__ + 1) * vr_dim1 + 1], &c__1); + i__2 = *n; + for (k = 1; k <= i__2; ++k) { +/* Computing 2nd power */ + r__1 = vr[k + i__ * vr_dim1]; +/* Computing 2nd power */ + r__2 = vr[k + (i__ + 1) * vr_dim1]; + work[iwrk + k - 1] = r__1 * r__1 + r__2 * r__2; +/* L30: */ + } + k = isamax_(n, &work[iwrk], &c__1); + slartg_(&vr[k + i__ * vr_dim1], &vr[k + (i__ + 1) * vr_dim1], + &cs, &sn, &r__); + srot_(n, &vr[i__ * vr_dim1 + 1], &c__1, &vr[(i__ + 1) * + vr_dim1 + 1], &c__1, &cs, &sn); + vr[k + (i__ + 1) * vr_dim1] = 0.f; + } +/* L40: */ + } + } + +/* Undo scaling if necessary */ + +L50: + if (scalea) { + i__1 = *n - *info; +/* Computing MAX */ + i__3 = *n - *info; + i__2 = max(i__3,1); + slascl_("G", &c__0, &c__0, &cscale, &anrm, &i__1, &c__1, &wr[*info + + 1], &i__2, &ierr); + i__1 = *n - *info; +/* Computing MAX */ + i__3 = *n - *info; + i__2 = max(i__3,1); + slascl_("G", &c__0, &c__0, &cscale, &anrm, &i__1, &c__1, &wi[*info + + 1], &i__2, &ierr); + if (*info > 0) { + i__1 = ilo - 1; + slascl_("G", &c__0, &c__0, &cscale, &anrm, &i__1, &c__1, &wr[1], + n, &ierr); + i__1 = ilo - 1; + slascl_("G", &c__0, &c__0, &cscale, &anrm, &i__1, &c__1, &wi[1], + n, &ierr); + } + } + + work[1] = (real) maxwrk; + return 0; + +/* End of SGEEV */ + +} /* sgeev_ */ + +/* Subroutine */ int sgehd2_(integer *n, integer *ilo, integer *ihi, real *a, + integer *lda, real *tau, real *work, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + + /* Local variables */ + static integer i__; + static real aii; + extern /* Subroutine */ int slarf_(char *, integer *, integer *, real *, + integer *, real *, real *, integer *, real *), xerbla_( + char *, integer *), slarfg_(integer *, real *, real *, + integer *, real *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SGEHD2 reduces a real general matrix A to upper Hessenberg form H by + an orthogonal similarity transformation: Q' * A * Q = H . + + Arguments + ========= + + N (input) INTEGER + The order of the matrix A. N >= 0. + + ILO (input) INTEGER + IHI (input) INTEGER + It is assumed that A is already upper triangular in rows + and columns 1:ILO-1 and IHI+1:N. ILO and IHI are normally + set by a previous call to SGEBAL; otherwise they should be + set to 1 and N respectively. See Further Details. + 1 <= ILO <= IHI <= max(1,N). + + A (input/output) REAL array, dimension (LDA,N) + On entry, the n by n general matrix to be reduced. + On exit, the upper triangle and the first subdiagonal of A + are overwritten with the upper Hessenberg matrix H, and the + elements below the first subdiagonal, with the array TAU, + represent the orthogonal matrix Q as a product of elementary + reflectors. See Further Details. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + TAU (output) REAL array, dimension (N-1) + The scalar factors of the elementary reflectors (see Further + Details). + + WORK (workspace) REAL array, dimension (N) + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + + Further Details + =============== + + The matrix Q is represented as a product of (ihi-ilo) elementary + reflectors + + Q = H(ilo) H(ilo+1) . . . H(ihi-1). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(1:i) = 0, v(i+1) = 1 and v(ihi+1:n) = 0; v(i+2:ihi) is stored on + exit in A(i+2:ihi,i), and tau in TAU(i). + + The contents of A are illustrated by the following example, with + n = 7, ilo = 2 and ihi = 6: + + on entry, on exit, + + ( a a a a a a a ) ( a a h h h h a ) + ( a a a a a a ) ( a h h h h a ) + ( a a a a a a ) ( h h h h h h ) + ( a a a a a a ) ( v2 h h h h h ) + ( a a a a a a ) ( v2 v3 h h h h ) + ( a a a a a a ) ( v2 v3 v4 h h h ) + ( a ) ( a ) + + where a denotes an element of the original matrix A, h denotes a + modified element of the upper Hessenberg matrix H, and vi denotes an + element of the vector defining H(i). + + ===================================================================== + + + Test the input parameters +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; + if (*n < 0) { + *info = -1; + } else if (*ilo < 1 || *ilo > max(1,*n)) { + *info = -2; + } else if (*ihi < min(*ilo,*n) || *ihi > *n) { + *info = -3; + } else if (*lda < max(1,*n)) { + *info = -5; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGEHD2", &i__1); + return 0; + } + + i__1 = *ihi - 1; + for (i__ = *ilo; i__ <= i__1; ++i__) { + +/* Compute elementary reflector H(i) to annihilate A(i+2:ihi,i) */ + + i__2 = *ihi - i__; +/* Computing MIN */ + i__3 = i__ + 2; + slarfg_(&i__2, &a[i__ + 1 + i__ * a_dim1], &a[min(i__3,*n) + i__ * + a_dim1], &c__1, &tau[i__]); + aii = a[i__ + 1 + i__ * a_dim1]; + a[i__ + 1 + i__ * a_dim1] = 1.f; + +/* Apply H(i) to A(1:ihi,i+1:ihi) from the right */ + + i__2 = *ihi - i__; + slarf_("Right", ihi, &i__2, &a[i__ + 1 + i__ * a_dim1], &c__1, &tau[ + i__], &a[(i__ + 1) * a_dim1 + 1], lda, &work[1]); + +/* Apply H(i) to A(i+1:ihi,i+1:n) from the left */ + + i__2 = *ihi - i__; + i__3 = *n - i__; + slarf_("Left", &i__2, &i__3, &a[i__ + 1 + i__ * a_dim1], &c__1, &tau[ + i__], &a[i__ + 1 + (i__ + 1) * a_dim1], lda, &work[1]); + + a[i__ + 1 + i__ * a_dim1] = aii; +/* L10: */ + } + + return 0; + +/* End of SGEHD2 */ + +} /* sgehd2_ */ + +/* Subroutine */ int sgehrd_(integer *n, integer *ilo, integer *ihi, real *a, + integer *lda, real *tau, real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3, i__4; + + /* Local variables */ + static integer i__; + static real t[4160] /* was [65][64] */; + static integer ib; + static real ei; + static integer nb, nh, nx, iws, nbmin, iinfo; + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *), sgehd2_(integer *, integer *, + integer *, real *, integer *, real *, real *, integer *), slarfb_( + char *, char *, char *, char *, integer *, integer *, integer *, + real *, integer *, real *, integer *, real *, integer *, real *, + integer *), slahrd_(integer *, + integer *, integer *, real *, integer *, real *, real *, integer * + , real *, integer *), xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + static integer ldwork, lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SGEHRD reduces a real general matrix A to upper Hessenberg form H by + an orthogonal similarity transformation: Q' * A * Q = H . + + Arguments + ========= + + N (input) INTEGER + The order of the matrix A. N >= 0. + + ILO (input) INTEGER + IHI (input) INTEGER + It is assumed that A is already upper triangular in rows + and columns 1:ILO-1 and IHI+1:N. ILO and IHI are normally + set by a previous call to SGEBAL; otherwise they should be + set to 1 and N respectively. See Further Details. + 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the N-by-N general matrix to be reduced. + On exit, the upper triangle and the first subdiagonal of A + are overwritten with the upper Hessenberg matrix H, and the + elements below the first subdiagonal, with the array TAU, + represent the orthogonal matrix Q as a product of elementary + reflectors. See Further Details. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + TAU (output) REAL array, dimension (N-1) + The scalar factors of the elementary reflectors (see Further + Details). Elements 1:ILO-1 and IHI:N-1 of TAU are set to + zero. + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The length of the array WORK. LWORK >= max(1,N). + For optimum performance LWORK >= N*NB, where NB is the + optimal blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value. + + Further Details + =============== + + The matrix Q is represented as a product of (ihi-ilo) elementary + reflectors + + Q = H(ilo) H(ilo+1) . . . H(ihi-1). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(1:i) = 0, v(i+1) = 1 and v(ihi+1:n) = 0; v(i+2:ihi) is stored on + exit in A(i+2:ihi,i), and tau in TAU(i). + + The contents of A are illustrated by the following example, with + n = 7, ilo = 2 and ihi = 6: + + on entry, on exit, + + ( a a a a a a a ) ( a a h h h h a ) + ( a a a a a a ) ( a h h h h a ) + ( a a a a a a ) ( h h h h h h ) + ( a a a a a a ) ( v2 h h h h h ) + ( a a a a a a ) ( v2 v3 h h h h ) + ( a a a a a a ) ( v2 v3 v4 h h h ) + ( a ) ( a ) + + where a denotes an element of the original matrix A, h denotes a + modified element of the upper Hessenberg matrix H, and vi denotes an + element of the vector defining H(i). + + ===================================================================== + + + Test the input parameters +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; +/* Computing MIN */ + i__1 = 64, i__2 = ilaenv_(&c__1, "SGEHRD", " ", n, ilo, ihi, &c_n1, ( + ftnlen)6, (ftnlen)1); + nb = min(i__1,i__2); + lwkopt = *n * nb; + work[1] = (real) lwkopt; + lquery = *lwork == -1; + if (*n < 0) { + *info = -1; + } else if (*ilo < 1 || *ilo > max(1,*n)) { + *info = -2; + } else if (*ihi < min(*ilo,*n) || *ihi > *n) { + *info = -3; + } else if (*lda < max(1,*n)) { + *info = -5; + } else if (*lwork < max(1,*n) && ! lquery) { + *info = -8; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGEHRD", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Set elements 1:ILO-1 and IHI:N-1 of TAU to zero */ + + i__1 = *ilo - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + tau[i__] = 0.f; +/* L10: */ + } + i__1 = *n - 1; + for (i__ = max(1,*ihi); i__ <= i__1; ++i__) { + tau[i__] = 0.f; +/* L20: */ + } + +/* Quick return if possible */ + + nh = *ihi - *ilo + 1; + if (nh <= 1) { + work[1] = 1.f; + return 0; + } + +/* + Determine the block size. + + Computing MIN +*/ + i__1 = 64, i__2 = ilaenv_(&c__1, "SGEHRD", " ", n, ilo, ihi, &c_n1, ( + ftnlen)6, (ftnlen)1); + nb = min(i__1,i__2); + nbmin = 2; + iws = 1; + if (nb > 1 && nb < nh) { + +/* + Determine when to cross over from blocked to unblocked code + (last block is always handled by unblocked code). + + Computing MAX +*/ + i__1 = nb, i__2 = ilaenv_(&c__3, "SGEHRD", " ", n, ilo, ihi, &c_n1, ( + ftnlen)6, (ftnlen)1); + nx = max(i__1,i__2); + if (nx < nh) { + +/* Determine if workspace is large enough for blocked code. */ + + iws = *n * nb; + if (*lwork < iws) { + +/* + Not enough workspace to use optimal NB: determine the + minimum value of NB, and reduce NB or force use of + unblocked code. + + Computing MAX +*/ + i__1 = 2, i__2 = ilaenv_(&c__2, "SGEHRD", " ", n, ilo, ihi, & + c_n1, (ftnlen)6, (ftnlen)1); + nbmin = max(i__1,i__2); + if (*lwork >= *n * nbmin) { + nb = *lwork / *n; + } else { + nb = 1; + } + } + } + } + ldwork = *n; + + if (nb < nbmin || nb >= nh) { + +/* Use unblocked code below */ + + i__ = *ilo; + + } else { + +/* Use blocked code */ + + i__1 = *ihi - 1 - nx; + i__2 = nb; + for (i__ = *ilo; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { +/* Computing MIN */ + i__3 = nb, i__4 = *ihi - i__; + ib = min(i__3,i__4); + +/* + Reduce columns i:i+ib-1 to Hessenberg form, returning the + matrices V and T of the block reflector H = I - V*T*V' + which performs the reduction, and also the matrix Y = A*V*T +*/ + + slahrd_(ihi, &i__, &ib, &a[i__ * a_dim1 + 1], lda, &tau[i__], t, & + c__65, &work[1], &ldwork); + +/* + Apply the block reflector H to A(1:ihi,i+ib:ihi) from the + right, computing A := A - Y * V'. V(i+ib,ib-1) must be set + to 1. +*/ + + ei = a[i__ + ib + (i__ + ib - 1) * a_dim1]; + a[i__ + ib + (i__ + ib - 1) * a_dim1] = 1.f; + i__3 = *ihi - i__ - ib + 1; + sgemm_("No transpose", "Transpose", ihi, &i__3, &ib, &c_b151, & + work[1], &ldwork, &a[i__ + ib + i__ * a_dim1], lda, & + c_b15, &a[(i__ + ib) * a_dim1 + 1], lda); + a[i__ + ib + (i__ + ib - 1) * a_dim1] = ei; + +/* + Apply the block reflector H to A(i+1:ihi,i+ib:n) from the + left +*/ + + i__3 = *ihi - i__; + i__4 = *n - i__ - ib + 1; + slarfb_("Left", "Transpose", "Forward", "Columnwise", &i__3, & + i__4, &ib, &a[i__ + 1 + i__ * a_dim1], lda, t, &c__65, &a[ + i__ + 1 + (i__ + ib) * a_dim1], lda, &work[1], &ldwork); +/* L30: */ + } + } + +/* Use unblocked code to reduce the rest of the matrix */ + + sgehd2_(n, &i__, ihi, &a[a_offset], lda, &tau[1], &work[1], &iinfo); + work[1] = (real) iws; + + return 0; + +/* End of SGEHRD */ + +} /* sgehrd_ */ + +/* Subroutine */ int sgelq2_(integer *m, integer *n, real *a, integer *lda, + real *tau, real *work, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + + /* Local variables */ + static integer i__, k; + static real aii; + extern /* Subroutine */ int slarf_(char *, integer *, integer *, real *, + integer *, real *, real *, integer *, real *), xerbla_( + char *, integer *), slarfg_(integer *, real *, real *, + integer *, real *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SGELQ2 computes an LQ factorization of a real m by n matrix A: + A = L * Q. + + Arguments + ========= + + M (input) INTEGER + The number of rows of the matrix A. M >= 0. + + N (input) INTEGER + The number of columns of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the m by n matrix A. + On exit, the elements on and below the diagonal of the array + contain the m by min(m,n) lower trapezoidal matrix L (L is + lower triangular if m <= n); the elements above the diagonal, + with the array TAU, represent the orthogonal matrix Q as a + product of elementary reflectors (see Further Details). + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + TAU (output) REAL array, dimension (min(M,N)) + The scalar factors of the elementary reflectors (see Further + Details). + + WORK (workspace) REAL array, dimension (M) + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + Further Details + =============== + + The matrix Q is represented as a product of elementary reflectors + + Q = H(k) . . . H(2) H(1), where k = min(m,n). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(1:i-1) = 0 and v(i) = 1; v(i+1:n) is stored on exit in A(i,i+1:n), + and tau in TAU(i). + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; + if (*m < 0) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*m)) { + *info = -4; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGELQ2", &i__1); + return 0; + } + + k = min(*m,*n); + + i__1 = k; + for (i__ = 1; i__ <= i__1; ++i__) { + +/* Generate elementary reflector H(i) to annihilate A(i,i+1:n) */ + + i__2 = *n - i__ + 1; +/* Computing MIN */ + i__3 = i__ + 1; + slarfg_(&i__2, &a[i__ + i__ * a_dim1], &a[i__ + min(i__3,*n) * a_dim1] + , lda, &tau[i__]); + if (i__ < *m) { + +/* Apply H(i) to A(i+1:m,i:n) from the right */ + + aii = a[i__ + i__ * a_dim1]; + a[i__ + i__ * a_dim1] = 1.f; + i__2 = *m - i__; + i__3 = *n - i__ + 1; + slarf_("Right", &i__2, &i__3, &a[i__ + i__ * a_dim1], lda, &tau[ + i__], &a[i__ + 1 + i__ * a_dim1], lda, &work[1]); + a[i__ + i__ * a_dim1] = aii; + } +/* L10: */ + } + return 0; + +/* End of SGELQ2 */ + +} /* sgelq2_ */ + +/* Subroutine */ int sgelqf_(integer *m, integer *n, real *a, integer *lda, + real *tau, real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3, i__4; + + /* Local variables */ + static integer i__, k, ib, nb, nx, iws, nbmin, iinfo; + extern /* Subroutine */ int sgelq2_(integer *, integer *, real *, integer + *, real *, real *, integer *), slarfb_(char *, char *, char *, + char *, integer *, integer *, integer *, real *, integer *, real * + , integer *, real *, integer *, real *, integer *), xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slarft_(char *, char *, integer *, integer *, + real *, integer *, real *, real *, integer *); + static integer ldwork, lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SGELQF computes an LQ factorization of a real M-by-N matrix A: + A = L * Q. + + Arguments + ========= + + M (input) INTEGER + The number of rows of the matrix A. M >= 0. + + N (input) INTEGER + The number of columns of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the M-by-N matrix A. + On exit, the elements on and below the diagonal of the array + contain the m-by-min(m,n) lower trapezoidal matrix L (L is + lower triangular if m <= n); the elements above the diagonal, + with the array TAU, represent the orthogonal matrix Q as a + product of elementary reflectors (see Further Details). + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + TAU (output) REAL array, dimension (min(M,N)) + The scalar factors of the elementary reflectors (see Further + Details). + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. LWORK >= max(1,M). + For optimum performance LWORK >= M*NB, where NB is the + optimal blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + Further Details + =============== + + The matrix Q is represented as a product of elementary reflectors + + Q = H(k) . . . H(2) H(1), where k = min(m,n). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(1:i-1) = 0 and v(i) = 1; v(i+1:n) is stored on exit in A(i,i+1:n), + and tau in TAU(i). + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; + nb = ilaenv_(&c__1, "SGELQF", " ", m, n, &c_n1, &c_n1, (ftnlen)6, (ftnlen) + 1); + lwkopt = *m * nb; + work[1] = (real) lwkopt; + lquery = *lwork == -1; + if (*m < 0) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*m)) { + *info = -4; + } else if (*lwork < max(1,*m) && ! lquery) { + *info = -7; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGELQF", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + k = min(*m,*n); + if (k == 0) { + work[1] = 1.f; + return 0; + } + + nbmin = 2; + nx = 0; + iws = *m; + if (nb > 1 && nb < k) { + +/* + Determine when to cross over from blocked to unblocked code. + + Computing MAX +*/ + i__1 = 0, i__2 = ilaenv_(&c__3, "SGELQF", " ", m, n, &c_n1, &c_n1, ( + ftnlen)6, (ftnlen)1); + nx = max(i__1,i__2); + if (nx < k) { + +/* Determine if workspace is large enough for blocked code. */ + + ldwork = *m; + iws = ldwork * nb; + if (*lwork < iws) { + +/* + Not enough workspace to use optimal NB: reduce NB and + determine the minimum value of NB. +*/ + + nb = *lwork / ldwork; +/* Computing MAX */ + i__1 = 2, i__2 = ilaenv_(&c__2, "SGELQF", " ", m, n, &c_n1, & + c_n1, (ftnlen)6, (ftnlen)1); + nbmin = max(i__1,i__2); + } + } + } + + if (nb >= nbmin && nb < k && nx < k) { + +/* Use blocked code initially */ + + i__1 = k - nx; + i__2 = nb; + for (i__ = 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { +/* Computing MIN */ + i__3 = k - i__ + 1; + ib = min(i__3,nb); + +/* + Compute the LQ factorization of the current block + A(i:i+ib-1,i:n) +*/ + + i__3 = *n - i__ + 1; + sgelq2_(&ib, &i__3, &a[i__ + i__ * a_dim1], lda, &tau[i__], &work[ + 1], &iinfo); + if (i__ + ib <= *m) { + +/* + Form the triangular factor of the block reflector + H = H(i) H(i+1) . . . H(i+ib-1) +*/ + + i__3 = *n - i__ + 1; + slarft_("Forward", "Rowwise", &i__3, &ib, &a[i__ + i__ * + a_dim1], lda, &tau[i__], &work[1], &ldwork); + +/* Apply H to A(i+ib:m,i:n) from the right */ + + i__3 = *m - i__ - ib + 1; + i__4 = *n - i__ + 1; + slarfb_("Right", "No transpose", "Forward", "Rowwise", &i__3, + &i__4, &ib, &a[i__ + i__ * a_dim1], lda, &work[1], & + ldwork, &a[i__ + ib + i__ * a_dim1], lda, &work[ib + + 1], &ldwork); + } +/* L10: */ + } + } else { + i__ = 1; + } + +/* Use unblocked code to factor the last or only block. */ + + if (i__ <= k) { + i__2 = *m - i__ + 1; + i__1 = *n - i__ + 1; + sgelq2_(&i__2, &i__1, &a[i__ + i__ * a_dim1], lda, &tau[i__], &work[1] + , &iinfo); + } + + work[1] = (real) iws; + return 0; + +/* End of SGELQF */ + +} /* sgelqf_ */ + +/* Subroutine */ int sgeqr2_(integer *m, integer *n, real *a, integer *lda, + real *tau, real *work, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + + /* Local variables */ + static integer i__, k; + static real aii; + extern /* Subroutine */ int slarf_(char *, integer *, integer *, real *, + integer *, real *, real *, integer *, real *), xerbla_( + char *, integer *), slarfg_(integer *, real *, real *, + integer *, real *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SGEQR2 computes a QR factorization of a real m by n matrix A: + A = Q * R. + + Arguments + ========= + + M (input) INTEGER + The number of rows of the matrix A. M >= 0. + + N (input) INTEGER + The number of columns of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the m by n matrix A. + On exit, the elements on and above the diagonal of the array + contain the min(m,n) by n upper trapezoidal matrix R (R is + upper triangular if m >= n); the elements below the diagonal, + with the array TAU, represent the orthogonal matrix Q as a + product of elementary reflectors (see Further Details). + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + TAU (output) REAL array, dimension (min(M,N)) + The scalar factors of the elementary reflectors (see Further + Details). + + WORK (workspace) REAL array, dimension (N) + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + Further Details + =============== + + The matrix Q is represented as a product of elementary reflectors + + Q = H(1) H(2) . . . H(k), where k = min(m,n). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i), + and tau in TAU(i). + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; + if (*m < 0) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*m)) { + *info = -4; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGEQR2", &i__1); + return 0; + } + + k = min(*m,*n); + + i__1 = k; + for (i__ = 1; i__ <= i__1; ++i__) { + +/* Generate elementary reflector H(i) to annihilate A(i+1:m,i) */ + + i__2 = *m - i__ + 1; +/* Computing MIN */ + i__3 = i__ + 1; + slarfg_(&i__2, &a[i__ + i__ * a_dim1], &a[min(i__3,*m) + i__ * a_dim1] + , &c__1, &tau[i__]); + if (i__ < *n) { + +/* Apply H(i) to A(i:m,i+1:n) from the left */ + + aii = a[i__ + i__ * a_dim1]; + a[i__ + i__ * a_dim1] = 1.f; + i__2 = *m - i__ + 1; + i__3 = *n - i__; + slarf_("Left", &i__2, &i__3, &a[i__ + i__ * a_dim1], &c__1, &tau[ + i__], &a[i__ + (i__ + 1) * a_dim1], lda, &work[1]); + a[i__ + i__ * a_dim1] = aii; + } +/* L10: */ + } + return 0; + +/* End of SGEQR2 */ + +} /* sgeqr2_ */ + +/* Subroutine */ int sgeqrf_(integer *m, integer *n, real *a, integer *lda, + real *tau, real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3, i__4; + + /* Local variables */ + static integer i__, k, ib, nb, nx, iws, nbmin, iinfo; + extern /* Subroutine */ int sgeqr2_(integer *, integer *, real *, integer + *, real *, real *, integer *), slarfb_(char *, char *, char *, + char *, integer *, integer *, integer *, real *, integer *, real * + , integer *, real *, integer *, real *, integer *), xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slarft_(char *, char *, integer *, integer *, + real *, integer *, real *, real *, integer *); + static integer ldwork, lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SGEQRF computes a QR factorization of a real M-by-N matrix A: + A = Q * R. + + Arguments + ========= + + M (input) INTEGER + The number of rows of the matrix A. M >= 0. + + N (input) INTEGER + The number of columns of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the M-by-N matrix A. + On exit, the elements on and above the diagonal of the array + contain the min(M,N)-by-N upper trapezoidal matrix R (R is + upper triangular if m >= n); the elements below the diagonal, + with the array TAU, represent the orthogonal matrix Q as a + product of min(m,n) elementary reflectors (see Further + Details). + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + TAU (output) REAL array, dimension (min(M,N)) + The scalar factors of the elementary reflectors (see Further + Details). + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. LWORK >= max(1,N). + For optimum performance LWORK >= N*NB, where NB is + the optimal blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + Further Details + =============== + + The matrix Q is represented as a product of elementary reflectors + + Q = H(1) H(2) . . . H(k), where k = min(m,n). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i), + and tau in TAU(i). + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; + nb = ilaenv_(&c__1, "SGEQRF", " ", m, n, &c_n1, &c_n1, (ftnlen)6, (ftnlen) + 1); + lwkopt = *n * nb; + work[1] = (real) lwkopt; + lquery = *lwork == -1; + if (*m < 0) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*m)) { + *info = -4; + } else if (*lwork < max(1,*n) && ! lquery) { + *info = -7; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGEQRF", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + k = min(*m,*n); + if (k == 0) { + work[1] = 1.f; + return 0; + } + + nbmin = 2; + nx = 0; + iws = *n; + if (nb > 1 && nb < k) { + +/* + Determine when to cross over from blocked to unblocked code. + + Computing MAX +*/ + i__1 = 0, i__2 = ilaenv_(&c__3, "SGEQRF", " ", m, n, &c_n1, &c_n1, ( + ftnlen)6, (ftnlen)1); + nx = max(i__1,i__2); + if (nx < k) { + +/* Determine if workspace is large enough for blocked code. */ + + ldwork = *n; + iws = ldwork * nb; + if (*lwork < iws) { + +/* + Not enough workspace to use optimal NB: reduce NB and + determine the minimum value of NB. +*/ + + nb = *lwork / ldwork; +/* Computing MAX */ + i__1 = 2, i__2 = ilaenv_(&c__2, "SGEQRF", " ", m, n, &c_n1, & + c_n1, (ftnlen)6, (ftnlen)1); + nbmin = max(i__1,i__2); + } + } + } + + if (nb >= nbmin && nb < k && nx < k) { + +/* Use blocked code initially */ + + i__1 = k - nx; + i__2 = nb; + for (i__ = 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { +/* Computing MIN */ + i__3 = k - i__ + 1; + ib = min(i__3,nb); + +/* + Compute the QR factorization of the current block + A(i:m,i:i+ib-1) +*/ + + i__3 = *m - i__ + 1; + sgeqr2_(&i__3, &ib, &a[i__ + i__ * a_dim1], lda, &tau[i__], &work[ + 1], &iinfo); + if (i__ + ib <= *n) { + +/* + Form the triangular factor of the block reflector + H = H(i) H(i+1) . . . H(i+ib-1) +*/ + + i__3 = *m - i__ + 1; + slarft_("Forward", "Columnwise", &i__3, &ib, &a[i__ + i__ * + a_dim1], lda, &tau[i__], &work[1], &ldwork); + +/* Apply H' to A(i:m,i+ib:n) from the left */ + + i__3 = *m - i__ + 1; + i__4 = *n - i__ - ib + 1; + slarfb_("Left", "Transpose", "Forward", "Columnwise", &i__3, & + i__4, &ib, &a[i__ + i__ * a_dim1], lda, &work[1], & + ldwork, &a[i__ + (i__ + ib) * a_dim1], lda, &work[ib + + 1], &ldwork); + } +/* L10: */ + } + } else { + i__ = 1; + } + +/* Use unblocked code to factor the last or only block. */ + + if (i__ <= k) { + i__2 = *m - i__ + 1; + i__1 = *n - i__ + 1; + sgeqr2_(&i__2, &i__1, &a[i__ + i__ * a_dim1], lda, &tau[i__], &work[1] + , &iinfo); + } + + work[1] = (real) iws; + return 0; + +/* End of SGEQRF */ + +} /* sgeqrf_ */ + +/* Subroutine */ int sgesdd_(char *jobz, integer *m, integer *n, real *a, + integer *lda, real *s, real *u, integer *ldu, real *vt, integer *ldvt, + real *work, integer *lwork, integer *iwork, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, u_dim1, u_offset, vt_dim1, vt_offset, i__1, + i__2, i__3; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static integer i__, ie, il, ir, iu, blk; + static real dum[1], eps; + static integer ivt, iscl; + static real anrm; + static integer idum[1], ierr, itau; + extern logical lsame_(char *, char *); + static integer chunk; + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *); + static integer minmn, wrkbl, itaup, itauq, mnthr; + static logical wntqa; + static integer nwork; + static logical wntqn, wntqo, wntqs; + static integer bdspac; + extern /* Subroutine */ int sbdsdc_(char *, char *, integer *, real *, + real *, real *, integer *, real *, integer *, real *, integer *, + real *, integer *, integer *), sgebrd_(integer *, + integer *, real *, integer *, real *, real *, real *, real *, + real *, integer *, integer *); + extern doublereal slamch_(char *), slange_(char *, integer *, + integer *, real *, integer *, real *); + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + static real bignum; + extern /* Subroutine */ int sgelqf_(integer *, integer *, real *, integer + *, real *, real *, integer *, integer *), slascl_(char *, integer + *, integer *, real *, real *, integer *, integer *, real *, + integer *, integer *), sgeqrf_(integer *, integer *, real + *, integer *, real *, real *, integer *, integer *), slacpy_(char + *, integer *, integer *, real *, integer *, real *, integer *), slaset_(char *, integer *, integer *, real *, real *, + real *, integer *), sorgbr_(char *, integer *, integer *, + integer *, real *, integer *, real *, real *, integer *, integer * + ); + static integer ldwrkl; + extern /* Subroutine */ int sormbr_(char *, char *, char *, integer *, + integer *, integer *, real *, integer *, real *, real *, integer * + , real *, integer *, integer *); + static integer ldwrkr, minwrk, ldwrku, maxwrk; + extern /* Subroutine */ int sorglq_(integer *, integer *, integer *, real + *, integer *, real *, real *, integer *, integer *); + static integer ldwkvt; + static real smlnum; + static logical wntqas; + extern /* Subroutine */ int sorgqr_(integer *, integer *, integer *, real + *, integer *, real *, real *, integer *, integer *); + static logical lquery; + + +/* + -- LAPACK driver routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1999 + + + Purpose + ======= + + SGESDD computes the singular value decomposition (SVD) of a real + M-by-N matrix A, optionally computing the left and right singular + vectors. If singular vectors are desired, it uses a + divide-and-conquer algorithm. + + The SVD is written + + A = U * SIGMA * transpose(V) + + where SIGMA is an M-by-N matrix which is zero except for its + min(m,n) diagonal elements, U is an M-by-M orthogonal matrix, and + V is an N-by-N orthogonal matrix. The diagonal elements of SIGMA + are the singular values of A; they are real and non-negative, and + are returned in descending order. The first min(m,n) columns of + U and V are the left and right singular vectors of A. + + Note that the routine returns VT = V**T, not V. + + The divide and conquer algorithm makes very mild assumptions about + floating point arithmetic. It will work on machines with a guard + digit in add/subtract, or on those binary machines without guard + digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or + Cray-2. It could conceivably fail on hexadecimal or decimal machines + without guard digits, but we know of none. + + Arguments + ========= + + JOBZ (input) CHARACTER*1 + Specifies options for computing all or part of the matrix U: + = 'A': all M columns of U and all N rows of V**T are + returned in the arrays U and VT; + = 'S': the first min(M,N) columns of U and the first + min(M,N) rows of V**T are returned in the arrays U + and VT; + = 'O': If M >= N, the first N columns of U are overwritten + on the array A and all rows of V**T are returned in + the array VT; + otherwise, all columns of U are returned in the + array U and the first M rows of V**T are overwritten + in the array VT; + = 'N': no columns of U or rows of V**T are computed. + + M (input) INTEGER + The number of rows of the input matrix A. M >= 0. + + N (input) INTEGER + The number of columns of the input matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the M-by-N matrix A. + On exit, + if JOBZ = 'O', A is overwritten with the first N columns + of U (the left singular vectors, stored + columnwise) if M >= N; + A is overwritten with the first M rows + of V**T (the right singular vectors, stored + rowwise) otherwise. + if JOBZ .ne. 'O', the contents of A are destroyed. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + S (output) REAL array, dimension (min(M,N)) + The singular values of A, sorted so that S(i) >= S(i+1). + + U (output) REAL array, dimension (LDU,UCOL) + UCOL = M if JOBZ = 'A' or JOBZ = 'O' and M < N; + UCOL = min(M,N) if JOBZ = 'S'. + If JOBZ = 'A' or JOBZ = 'O' and M < N, U contains the M-by-M + orthogonal matrix U; + if JOBZ = 'S', U contains the first min(M,N) columns of U + (the left singular vectors, stored columnwise); + if JOBZ = 'O' and M >= N, or JOBZ = 'N', U is not referenced. + + LDU (input) INTEGER + The leading dimension of the array U. LDU >= 1; if + JOBZ = 'S' or 'A' or JOBZ = 'O' and M < N, LDU >= M. + + VT (output) REAL array, dimension (LDVT,N) + If JOBZ = 'A' or JOBZ = 'O' and M >= N, VT contains the + N-by-N orthogonal matrix V**T; + if JOBZ = 'S', VT contains the first min(M,N) rows of + V**T (the right singular vectors, stored rowwise); + if JOBZ = 'O' and M < N, or JOBZ = 'N', VT is not referenced. + + LDVT (input) INTEGER + The leading dimension of the array VT. LDVT >= 1; if + JOBZ = 'A' or JOBZ = 'O' and M >= N, LDVT >= N; + if JOBZ = 'S', LDVT >= min(M,N). + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK; + + LWORK (input) INTEGER + The dimension of the array WORK. LWORK >= 1. + If JOBZ = 'N', + LWORK >= 3*min(M,N) + max(max(M,N),6*min(M,N)). + If JOBZ = 'O', + LWORK >= 3*min(M,N)*min(M,N) + + max(max(M,N),5*min(M,N)*min(M,N)+4*min(M,N)). + If JOBZ = 'S' or 'A' + LWORK >= 3*min(M,N)*min(M,N) + + max(max(M,N),4*min(M,N)*min(M,N)+4*min(M,N)). + For good performance, LWORK should generally be larger. + If LWORK < 0 but other input arguments are legal, WORK(1) + returns the optimal LWORK. + + IWORK (workspace) INTEGER array, dimension (8*min(M,N)) + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: SBDSDC did not converge, updating process failed. + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --s; + u_dim1 = *ldu; + u_offset = 1 + u_dim1; + u -= u_offset; + vt_dim1 = *ldvt; + vt_offset = 1 + vt_dim1; + vt -= vt_offset; + --work; + --iwork; + + /* Function Body */ + *info = 0; + minmn = min(*m,*n); + mnthr = (integer) (minmn * 11.f / 6.f); + wntqa = lsame_(jobz, "A"); + wntqs = lsame_(jobz, "S"); + wntqas = wntqa || wntqs; + wntqo = lsame_(jobz, "O"); + wntqn = lsame_(jobz, "N"); + minwrk = 1; + maxwrk = 1; + lquery = *lwork == -1; + + if (! (wntqa || wntqs || wntqo || wntqn)) { + *info = -1; + } else if (*m < 0) { + *info = -2; + } else if (*n < 0) { + *info = -3; + } else if (*lda < max(1,*m)) { + *info = -5; + } else if (*ldu < 1 || wntqas && *ldu < *m || wntqo && *m < *n && *ldu < * + m) { + *info = -8; + } else if (*ldvt < 1 || wntqa && *ldvt < *n || wntqs && *ldvt < minmn || + wntqo && *m >= *n && *ldvt < *n) { + *info = -10; + } + +/* + Compute workspace + (Note: Comments in the code beginning "Workspace:" describe the + minimal amount of workspace needed at that point in the code, + as well as the preferred amount for good performance. + NB refers to the optimal block size for the immediately + following subroutine, as returned by ILAENV.) +*/ + + if (*info == 0 && *m > 0 && *n > 0) { + if (*m >= *n) { + +/* Compute space needed for SBDSDC */ + + if (wntqn) { + bdspac = *n * 7; + } else { + bdspac = *n * 3 * *n + (*n << 2); + } + if (*m >= mnthr) { + if (wntqn) { + +/* Path 1 (M much larger than N, JOBZ='N') */ + + wrkbl = *n + *n * ilaenv_(&c__1, "SGEQRF", " ", m, n, & + c_n1, &c_n1, (ftnlen)6, (ftnlen)1); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + (*n << 1) * ilaenv_(&c__1, + "SGEBRD", " ", n, n, &c_n1, &c_n1, (ftnlen)6, ( + ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *n; + maxwrk = max(i__1,i__2); + minwrk = bdspac + *n; + } else if (wntqo) { + +/* Path 2 (M much larger than N, JOBZ='O') */ + + wrkbl = *n + *n * ilaenv_(&c__1, "SGEQRF", " ", m, n, & + c_n1, &c_n1, (ftnlen)6, (ftnlen)1); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n + *n * ilaenv_(&c__1, "SORGQR", + " ", m, n, n, &c_n1, (ftnlen)6, (ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + (*n << 1) * ilaenv_(&c__1, + "SGEBRD", " ", n, n, &c_n1, &c_n1, (ftnlen)6, ( + ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *n * ilaenv_(&c__1, "SORMBR" + , "QLN", n, n, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *n * ilaenv_(&c__1, "SORMBR" + , "PRT", n, n, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *n * 3; + wrkbl = max(i__1,i__2); + maxwrk = wrkbl + (*n << 1) * *n; + minwrk = bdspac + (*n << 1) * *n + *n * 3; + } else if (wntqs) { + +/* Path 3 (M much larger than N, JOBZ='S') */ + + wrkbl = *n + *n * ilaenv_(&c__1, "SGEQRF", " ", m, n, & + c_n1, &c_n1, (ftnlen)6, (ftnlen)1); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n + *n * ilaenv_(&c__1, "SORGQR", + " ", m, n, n, &c_n1, (ftnlen)6, (ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + (*n << 1) * ilaenv_(&c__1, + "SGEBRD", " ", n, n, &c_n1, &c_n1, (ftnlen)6, ( + ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *n * ilaenv_(&c__1, "SORMBR" + , "QLN", n, n, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *n * ilaenv_(&c__1, "SORMBR" + , "PRT", n, n, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *n * 3; + wrkbl = max(i__1,i__2); + maxwrk = wrkbl + *n * *n; + minwrk = bdspac + *n * *n + *n * 3; + } else if (wntqa) { + +/* Path 4 (M much larger than N, JOBZ='A') */ + + wrkbl = *n + *n * ilaenv_(&c__1, "SGEQRF", " ", m, n, & + c_n1, &c_n1, (ftnlen)6, (ftnlen)1); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n + *m * ilaenv_(&c__1, "SORGQR", + " ", m, m, n, &c_n1, (ftnlen)6, (ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + (*n << 1) * ilaenv_(&c__1, + "SGEBRD", " ", n, n, &c_n1, &c_n1, (ftnlen)6, ( + ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *n * ilaenv_(&c__1, "SORMBR" + , "QLN", n, n, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *n * ilaenv_(&c__1, "SORMBR" + , "PRT", n, n, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *n * 3; + wrkbl = max(i__1,i__2); + maxwrk = wrkbl + *n * *n; + minwrk = bdspac + *n * *n + *n * 3; + } + } else { + +/* Path 5 (M at least N, but not much larger) */ + + wrkbl = *n * 3 + (*m + *n) * ilaenv_(&c__1, "SGEBRD", " ", m, + n, &c_n1, &c_n1, (ftnlen)6, (ftnlen)1); + if (wntqn) { +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *n * 3; + maxwrk = max(i__1,i__2); + minwrk = *n * 3 + max(*m,bdspac); + } else if (wntqo) { +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *n * ilaenv_(&c__1, "SORMBR" + , "QLN", m, n, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *n * ilaenv_(&c__1, "SORMBR" + , "PRT", n, n, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *n * 3; + wrkbl = max(i__1,i__2); + maxwrk = wrkbl + *m * *n; +/* Computing MAX */ + i__1 = *m, i__2 = *n * *n + bdspac; + minwrk = *n * 3 + max(i__1,i__2); + } else if (wntqs) { +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *n * ilaenv_(&c__1, "SORMBR" + , "QLN", m, n, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *n * ilaenv_(&c__1, "SORMBR" + , "PRT", n, n, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *n * 3; + maxwrk = max(i__1,i__2); + minwrk = *n * 3 + max(*m,bdspac); + } else if (wntqa) { +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "QLN", m, m, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *n * 3 + *n * ilaenv_(&c__1, "SORMBR" + , "PRT", n, n, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = maxwrk, i__2 = bdspac + *n * 3; + maxwrk = max(i__1,i__2); + minwrk = *n * 3 + max(*m,bdspac); + } + } + } else { + +/* Compute space needed for SBDSDC */ + + if (wntqn) { + bdspac = *m * 7; + } else { + bdspac = *m * 3 * *m + (*m << 2); + } + if (*n >= mnthr) { + if (wntqn) { + +/* Path 1t (N much larger than M, JOBZ='N') */ + + wrkbl = *m + *m * ilaenv_(&c__1, "SGELQF", " ", m, n, & + c_n1, &c_n1, (ftnlen)6, (ftnlen)1); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + (*m << 1) * ilaenv_(&c__1, + "SGEBRD", " ", m, m, &c_n1, &c_n1, (ftnlen)6, ( + ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *m; + maxwrk = max(i__1,i__2); + minwrk = bdspac + *m; + } else if (wntqo) { + +/* Path 2t (N much larger than M, JOBZ='O') */ + + wrkbl = *m + *m * ilaenv_(&c__1, "SGELQF", " ", m, n, & + c_n1, &c_n1, (ftnlen)6, (ftnlen)1); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m + *m * ilaenv_(&c__1, "SORGLQ", + " ", m, n, m, &c_n1, (ftnlen)6, (ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + (*m << 1) * ilaenv_(&c__1, + "SGEBRD", " ", m, m, &c_n1, &c_n1, (ftnlen)6, ( + ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "QLN", m, m, m, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "PRT", m, m, m, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *m * 3; + wrkbl = max(i__1,i__2); + maxwrk = wrkbl + (*m << 1) * *m; + minwrk = bdspac + (*m << 1) * *m + *m * 3; + } else if (wntqs) { + +/* Path 3t (N much larger than M, JOBZ='S') */ + + wrkbl = *m + *m * ilaenv_(&c__1, "SGELQF", " ", m, n, & + c_n1, &c_n1, (ftnlen)6, (ftnlen)1); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m + *m * ilaenv_(&c__1, "SORGLQ", + " ", m, n, m, &c_n1, (ftnlen)6, (ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + (*m << 1) * ilaenv_(&c__1, + "SGEBRD", " ", m, m, &c_n1, &c_n1, (ftnlen)6, ( + ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "QLN", m, m, m, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "PRT", m, m, m, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *m * 3; + wrkbl = max(i__1,i__2); + maxwrk = wrkbl + *m * *m; + minwrk = bdspac + *m * *m + *m * 3; + } else if (wntqa) { + +/* Path 4t (N much larger than M, JOBZ='A') */ + + wrkbl = *m + *m * ilaenv_(&c__1, "SGELQF", " ", m, n, & + c_n1, &c_n1, (ftnlen)6, (ftnlen)1); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m + *n * ilaenv_(&c__1, "SORGLQ", + " ", n, n, m, &c_n1, (ftnlen)6, (ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + (*m << 1) * ilaenv_(&c__1, + "SGEBRD", " ", m, m, &c_n1, &c_n1, (ftnlen)6, ( + ftnlen)1); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "QLN", m, m, m, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "PRT", m, m, m, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *m * 3; + wrkbl = max(i__1,i__2); + maxwrk = wrkbl + *m * *m; + minwrk = bdspac + *m * *m + *m * 3; + } + } else { + +/* Path 5t (N greater than M, but not much larger) */ + + wrkbl = *m * 3 + (*m + *n) * ilaenv_(&c__1, "SGEBRD", " ", m, + n, &c_n1, &c_n1, (ftnlen)6, (ftnlen)1); + if (wntqn) { +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *m * 3; + maxwrk = max(i__1,i__2); + minwrk = *m * 3 + max(*n,bdspac); + } else if (wntqo) { +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "QLN", m, m, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "PRT", m, n, m, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *m * 3; + wrkbl = max(i__1,i__2); + maxwrk = wrkbl + *m * *n; +/* Computing MAX */ + i__1 = *n, i__2 = *m * *m + bdspac; + minwrk = *m * 3 + max(i__1,i__2); + } else if (wntqs) { +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "QLN", m, m, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "PRT", m, n, m, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *m * 3; + maxwrk = max(i__1,i__2); + minwrk = *m * 3 + max(*n,bdspac); + } else if (wntqa) { +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "QLN", m, m, n, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = *m * 3 + *m * ilaenv_(&c__1, "SORMBR" + , "PRT", n, n, m, &c_n1, (ftnlen)6, (ftnlen)3); + wrkbl = max(i__1,i__2); +/* Computing MAX */ + i__1 = wrkbl, i__2 = bdspac + *m * 3; + maxwrk = max(i__1,i__2); + minwrk = *m * 3 + max(*n,bdspac); + } + } + } + work[1] = (real) maxwrk; + } + + if (*lwork < minwrk && ! lquery) { + *info = -12; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGESDD", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0) { + if (*lwork >= 1) { + work[1] = 1.f; + } + return 0; + } + +/* Get machine constants */ + + eps = slamch_("P"); + smlnum = sqrt(slamch_("S")) / eps; + bignum = 1.f / smlnum; + +/* Scale A if max element outside range [SMLNUM,BIGNUM] */ + + anrm = slange_("M", m, n, &a[a_offset], lda, dum); + iscl = 0; + if (anrm > 0.f && anrm < smlnum) { + iscl = 1; + slascl_("G", &c__0, &c__0, &anrm, &smlnum, m, n, &a[a_offset], lda, & + ierr); + } else if (anrm > bignum) { + iscl = 1; + slascl_("G", &c__0, &c__0, &anrm, &bignum, m, n, &a[a_offset], lda, & + ierr); + } + + if (*m >= *n) { + +/* + A has at least as many rows as columns. If A has sufficiently + more rows than columns, first reduce using the QR + decomposition (if sufficient workspace available) +*/ + + if (*m >= mnthr) { + + if (wntqn) { + +/* + Path 1 (M much larger than N, JOBZ='N') + No singular vectors to be computed +*/ + + itau = 1; + nwork = itau + *n; + +/* + Compute A=Q*R + (Workspace: need 2*N, prefer N+N*NB) +*/ + + i__1 = *lwork - nwork + 1; + sgeqrf_(m, n, &a[a_offset], lda, &work[itau], &work[nwork], & + i__1, &ierr); + +/* Zero out below R */ + + i__1 = *n - 1; + i__2 = *n - 1; + slaset_("L", &i__1, &i__2, &c_b29, &c_b29, &a[a_dim1 + 2], + lda); + ie = 1; + itauq = ie + *n; + itaup = itauq + *n; + nwork = itaup + *n; + +/* + Bidiagonalize R in A + (Workspace: need 4*N, prefer 3*N+2*N*NB) +*/ + + i__1 = *lwork - nwork + 1; + sgebrd_(n, n, &a[a_offset], lda, &s[1], &work[ie], &work[ + itauq], &work[itaup], &work[nwork], &i__1, &ierr); + nwork = ie + *n; + +/* + Perform bidiagonal SVD, computing singular values only + (Workspace: need N+BDSPAC) +*/ + + sbdsdc_("U", "N", n, &s[1], &work[ie], dum, &c__1, dum, &c__1, + dum, idum, &work[nwork], &iwork[1], info); + + } else if (wntqo) { + +/* + Path 2 (M much larger than N, JOBZ = 'O') + N left singular vectors to be overwritten on A and + N right singular vectors to be computed in VT +*/ + + ir = 1; + +/* WORK(IR) is LDWRKR by N */ + + if (*lwork >= *lda * *n + *n * *n + *n * 3 + bdspac) { + ldwrkr = *lda; + } else { + ldwrkr = (*lwork - *n * *n - *n * 3 - bdspac) / *n; + } + itau = ir + ldwrkr * *n; + nwork = itau + *n; + +/* + Compute A=Q*R + (Workspace: need N*N+2*N, prefer N*N+N+N*NB) +*/ + + i__1 = *lwork - nwork + 1; + sgeqrf_(m, n, &a[a_offset], lda, &work[itau], &work[nwork], & + i__1, &ierr); + +/* Copy R to WORK(IR), zeroing out below it */ + + slacpy_("U", n, n, &a[a_offset], lda, &work[ir], &ldwrkr); + i__1 = *n - 1; + i__2 = *n - 1; + slaset_("L", &i__1, &i__2, &c_b29, &c_b29, &work[ir + 1], & + ldwrkr); + +/* + Generate Q in A + (Workspace: need N*N+2*N, prefer N*N+N+N*NB) +*/ + + i__1 = *lwork - nwork + 1; + sorgqr_(m, n, n, &a[a_offset], lda, &work[itau], &work[nwork], + &i__1, &ierr); + ie = itau; + itauq = ie + *n; + itaup = itauq + *n; + nwork = itaup + *n; + +/* + Bidiagonalize R in VT, copying result to WORK(IR) + (Workspace: need N*N+4*N, prefer N*N+3*N+2*N*NB) +*/ + + i__1 = *lwork - nwork + 1; + sgebrd_(n, n, &work[ir], &ldwrkr, &s[1], &work[ie], &work[ + itauq], &work[itaup], &work[nwork], &i__1, &ierr); + +/* WORK(IU) is N by N */ + + iu = nwork; + nwork = iu + *n * *n; + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagonal matrix in WORK(IU) and computing right + singular vectors of bidiagonal matrix in VT + (Workspace: need N+N*N+BDSPAC) +*/ + + sbdsdc_("U", "I", n, &s[1], &work[ie], &work[iu], n, &vt[ + vt_offset], ldvt, dum, idum, &work[nwork], &iwork[1], + info); + +/* + Overwrite WORK(IU) by left singular vectors of R + and VT by right singular vectors of R + (Workspace: need 2*N*N+3*N, prefer 2*N*N+2*N+N*NB) +*/ + + i__1 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", n, n, n, &work[ir], &ldwrkr, &work[ + itauq], &work[iu], n, &work[nwork], &i__1, &ierr); + i__1 = *lwork - nwork + 1; + sormbr_("P", "R", "T", n, n, n, &work[ir], &ldwrkr, &work[ + itaup], &vt[vt_offset], ldvt, &work[nwork], &i__1, & + ierr); + +/* + Multiply Q in A by left singular vectors of R in + WORK(IU), storing result in WORK(IR) and copying to A + (Workspace: need 2*N*N, prefer N*N+M*N) +*/ + + i__1 = *m; + i__2 = ldwrkr; + for (i__ = 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += + i__2) { +/* Computing MIN */ + i__3 = *m - i__ + 1; + chunk = min(i__3,ldwrkr); + sgemm_("N", "N", &chunk, n, n, &c_b15, &a[i__ + a_dim1], + lda, &work[iu], n, &c_b29, &work[ir], &ldwrkr); + slacpy_("F", &chunk, n, &work[ir], &ldwrkr, &a[i__ + + a_dim1], lda); +/* L10: */ + } + + } else if (wntqs) { + +/* + Path 3 (M much larger than N, JOBZ='S') + N left singular vectors to be computed in U and + N right singular vectors to be computed in VT +*/ + + ir = 1; + +/* WORK(IR) is N by N */ + + ldwrkr = *n; + itau = ir + ldwrkr * *n; + nwork = itau + *n; + +/* + Compute A=Q*R + (Workspace: need N*N+2*N, prefer N*N+N+N*NB) +*/ + + i__2 = *lwork - nwork + 1; + sgeqrf_(m, n, &a[a_offset], lda, &work[itau], &work[nwork], & + i__2, &ierr); + +/* Copy R to WORK(IR), zeroing out below it */ + + slacpy_("U", n, n, &a[a_offset], lda, &work[ir], &ldwrkr); + i__2 = *n - 1; + i__1 = *n - 1; + slaset_("L", &i__2, &i__1, &c_b29, &c_b29, &work[ir + 1], & + ldwrkr); + +/* + Generate Q in A + (Workspace: need N*N+2*N, prefer N*N+N+N*NB) +*/ + + i__2 = *lwork - nwork + 1; + sorgqr_(m, n, n, &a[a_offset], lda, &work[itau], &work[nwork], + &i__2, &ierr); + ie = itau; + itauq = ie + *n; + itaup = itauq + *n; + nwork = itaup + *n; + +/* + Bidiagonalize R in WORK(IR) + (Workspace: need N*N+4*N, prefer N*N+3*N+2*N*NB) +*/ + + i__2 = *lwork - nwork + 1; + sgebrd_(n, n, &work[ir], &ldwrkr, &s[1], &work[ie], &work[ + itauq], &work[itaup], &work[nwork], &i__2, &ierr); + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagoal matrix in U and computing right singular + vectors of bidiagonal matrix in VT + (Workspace: need N+BDSPAC) +*/ + + sbdsdc_("U", "I", n, &s[1], &work[ie], &u[u_offset], ldu, &vt[ + vt_offset], ldvt, dum, idum, &work[nwork], &iwork[1], + info); + +/* + Overwrite U by left singular vectors of R and VT + by right singular vectors of R + (Workspace: need N*N+3*N, prefer N*N+2*N+N*NB) +*/ + + i__2 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", n, n, n, &work[ir], &ldwrkr, &work[ + itauq], &u[u_offset], ldu, &work[nwork], &i__2, &ierr); + + i__2 = *lwork - nwork + 1; + sormbr_("P", "R", "T", n, n, n, &work[ir], &ldwrkr, &work[ + itaup], &vt[vt_offset], ldvt, &work[nwork], &i__2, & + ierr); + +/* + Multiply Q in A by left singular vectors of R in + WORK(IR), storing result in U + (Workspace: need N*N) +*/ + + slacpy_("F", n, n, &u[u_offset], ldu, &work[ir], &ldwrkr); + sgemm_("N", "N", m, n, n, &c_b15, &a[a_offset], lda, &work[ir] + , &ldwrkr, &c_b29, &u[u_offset], ldu); + + } else if (wntqa) { + +/* + Path 4 (M much larger than N, JOBZ='A') + M left singular vectors to be computed in U and + N right singular vectors to be computed in VT +*/ + + iu = 1; + +/* WORK(IU) is N by N */ + + ldwrku = *n; + itau = iu + ldwrku * *n; + nwork = itau + *n; + +/* + Compute A=Q*R, copying result to U + (Workspace: need N*N+2*N, prefer N*N+N+N*NB) +*/ + + i__2 = *lwork - nwork + 1; + sgeqrf_(m, n, &a[a_offset], lda, &work[itau], &work[nwork], & + i__2, &ierr); + slacpy_("L", m, n, &a[a_offset], lda, &u[u_offset], ldu); + +/* + Generate Q in U + (Workspace: need N*N+2*N, prefer N*N+N+N*NB) +*/ + i__2 = *lwork - nwork + 1; + sorgqr_(m, m, n, &u[u_offset], ldu, &work[itau], &work[nwork], + &i__2, &ierr); + +/* Produce R in A, zeroing out other entries */ + + i__2 = *n - 1; + i__1 = *n - 1; + slaset_("L", &i__2, &i__1, &c_b29, &c_b29, &a[a_dim1 + 2], + lda); + ie = itau; + itauq = ie + *n; + itaup = itauq + *n; + nwork = itaup + *n; + +/* + Bidiagonalize R in A + (Workspace: need N*N+4*N, prefer N*N+3*N+2*N*NB) +*/ + + i__2 = *lwork - nwork + 1; + sgebrd_(n, n, &a[a_offset], lda, &s[1], &work[ie], &work[ + itauq], &work[itaup], &work[nwork], &i__2, &ierr); + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagonal matrix in WORK(IU) and computing right + singular vectors of bidiagonal matrix in VT + (Workspace: need N+N*N+BDSPAC) +*/ + + sbdsdc_("U", "I", n, &s[1], &work[ie], &work[iu], n, &vt[ + vt_offset], ldvt, dum, idum, &work[nwork], &iwork[1], + info); + +/* + Overwrite WORK(IU) by left singular vectors of R and VT + by right singular vectors of R + (Workspace: need N*N+3*N, prefer N*N+2*N+N*NB) +*/ + + i__2 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", n, n, n, &a[a_offset], lda, &work[ + itauq], &work[iu], &ldwrku, &work[nwork], &i__2, & + ierr); + i__2 = *lwork - nwork + 1; + sormbr_("P", "R", "T", n, n, n, &a[a_offset], lda, &work[ + itaup], &vt[vt_offset], ldvt, &work[nwork], &i__2, & + ierr); + +/* + Multiply Q in U by left singular vectors of R in + WORK(IU), storing result in A + (Workspace: need N*N) +*/ + + sgemm_("N", "N", m, n, n, &c_b15, &u[u_offset], ldu, &work[iu] + , &ldwrku, &c_b29, &a[a_offset], lda); + +/* Copy left singular vectors of A from A to U */ + + slacpy_("F", m, n, &a[a_offset], lda, &u[u_offset], ldu); + + } + + } else { + +/* + M .LT. MNTHR + + Path 5 (M at least N, but not much larger) + Reduce to bidiagonal form without QR decomposition +*/ + + ie = 1; + itauq = ie + *n; + itaup = itauq + *n; + nwork = itaup + *n; + +/* + Bidiagonalize A + (Workspace: need 3*N+M, prefer 3*N+(M+N)*NB) +*/ + + i__2 = *lwork - nwork + 1; + sgebrd_(m, n, &a[a_offset], lda, &s[1], &work[ie], &work[itauq], & + work[itaup], &work[nwork], &i__2, &ierr); + if (wntqn) { + +/* + Perform bidiagonal SVD, only computing singular values + (Workspace: need N+BDSPAC) +*/ + + sbdsdc_("U", "N", n, &s[1], &work[ie], dum, &c__1, dum, &c__1, + dum, idum, &work[nwork], &iwork[1], info); + } else if (wntqo) { + iu = nwork; + if (*lwork >= *m * *n + *n * 3 + bdspac) { + +/* WORK( IU ) is M by N */ + + ldwrku = *m; + nwork = iu + ldwrku * *n; + slaset_("F", m, n, &c_b29, &c_b29, &work[iu], &ldwrku); + } else { + +/* WORK( IU ) is N by N */ + + ldwrku = *n; + nwork = iu + ldwrku * *n; + +/* WORK(IR) is LDWRKR by N */ + + ir = nwork; + ldwrkr = (*lwork - *n * *n - *n * 3) / *n; + } + nwork = iu + ldwrku * *n; + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagonal matrix in WORK(IU) and computing right + singular vectors of bidiagonal matrix in VT + (Workspace: need N+N*N+BDSPAC) +*/ + + sbdsdc_("U", "I", n, &s[1], &work[ie], &work[iu], &ldwrku, & + vt[vt_offset], ldvt, dum, idum, &work[nwork], &iwork[ + 1], info); + +/* + Overwrite VT by right singular vectors of A + (Workspace: need N*N+2*N, prefer N*N+N+N*NB) +*/ + + i__2 = *lwork - nwork + 1; + sormbr_("P", "R", "T", n, n, n, &a[a_offset], lda, &work[ + itaup], &vt[vt_offset], ldvt, &work[nwork], &i__2, & + ierr); + + if (*lwork >= *m * *n + *n * 3 + bdspac) { + +/* + Overwrite WORK(IU) by left singular vectors of A + (Workspace: need N*N+2*N, prefer N*N+N+N*NB) +*/ + + i__2 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", m, n, n, &a[a_offset], lda, &work[ + itauq], &work[iu], &ldwrku, &work[nwork], &i__2, & + ierr); + +/* Copy left singular vectors of A from WORK(IU) to A */ + + slacpy_("F", m, n, &work[iu], &ldwrku, &a[a_offset], lda); + } else { + +/* + Generate Q in A + (Workspace: need N*N+2*N, prefer N*N+N+N*NB) +*/ + + i__2 = *lwork - nwork + 1; + sorgbr_("Q", m, n, n, &a[a_offset], lda, &work[itauq], & + work[nwork], &i__2, &ierr); + +/* + Multiply Q in A by left singular vectors of + bidiagonal matrix in WORK(IU), storing result in + WORK(IR) and copying to A + (Workspace: need 2*N*N, prefer N*N+M*N) +*/ + + i__2 = *m; + i__1 = ldwrkr; + for (i__ = 1; i__1 < 0 ? i__ >= i__2 : i__ <= i__2; i__ += + i__1) { +/* Computing MIN */ + i__3 = *m - i__ + 1; + chunk = min(i__3,ldwrkr); + sgemm_("N", "N", &chunk, n, n, &c_b15, &a[i__ + + a_dim1], lda, &work[iu], &ldwrku, &c_b29, & + work[ir], &ldwrkr); + slacpy_("F", &chunk, n, &work[ir], &ldwrkr, &a[i__ + + a_dim1], lda); +/* L20: */ + } + } + + } else if (wntqs) { + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagonal matrix in U and computing right singular + vectors of bidiagonal matrix in VT + (Workspace: need N+BDSPAC) +*/ + + slaset_("F", m, n, &c_b29, &c_b29, &u[u_offset], ldu); + sbdsdc_("U", "I", n, &s[1], &work[ie], &u[u_offset], ldu, &vt[ + vt_offset], ldvt, dum, idum, &work[nwork], &iwork[1], + info); + +/* + Overwrite U by left singular vectors of A and VT + by right singular vectors of A + (Workspace: need 3*N, prefer 2*N+N*NB) +*/ + + i__1 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", m, n, n, &a[a_offset], lda, &work[ + itauq], &u[u_offset], ldu, &work[nwork], &i__1, &ierr); + i__1 = *lwork - nwork + 1; + sormbr_("P", "R", "T", n, n, n, &a[a_offset], lda, &work[ + itaup], &vt[vt_offset], ldvt, &work[nwork], &i__1, & + ierr); + } else if (wntqa) { + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagonal matrix in U and computing right singular + vectors of bidiagonal matrix in VT + (Workspace: need N+BDSPAC) +*/ + + slaset_("F", m, m, &c_b29, &c_b29, &u[u_offset], ldu); + sbdsdc_("U", "I", n, &s[1], &work[ie], &u[u_offset], ldu, &vt[ + vt_offset], ldvt, dum, idum, &work[nwork], &iwork[1], + info); + +/* Set the right corner of U to identity matrix */ + + i__1 = *m - *n; + i__2 = *m - *n; + slaset_("F", &i__1, &i__2, &c_b29, &c_b15, &u[*n + 1 + (*n + + 1) * u_dim1], ldu); + +/* + Overwrite U by left singular vectors of A and VT + by right singular vectors of A + (Workspace: need N*N+2*N+M, prefer N*N+2*N+M*NB) +*/ + + i__1 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", m, m, n, &a[a_offset], lda, &work[ + itauq], &u[u_offset], ldu, &work[nwork], &i__1, &ierr); + i__1 = *lwork - nwork + 1; + sormbr_("P", "R", "T", n, n, m, &a[a_offset], lda, &work[ + itaup], &vt[vt_offset], ldvt, &work[nwork], &i__1, & + ierr); + } + + } + + } else { + +/* + A has more columns than rows. If A has sufficiently more + columns than rows, first reduce using the LQ decomposition (if + sufficient workspace available) +*/ + + if (*n >= mnthr) { + + if (wntqn) { + +/* + Path 1t (N much larger than M, JOBZ='N') + No singular vectors to be computed +*/ + + itau = 1; + nwork = itau + *m; + +/* + Compute A=L*Q + (Workspace: need 2*M, prefer M+M*NB) +*/ + + i__1 = *lwork - nwork + 1; + sgelqf_(m, n, &a[a_offset], lda, &work[itau], &work[nwork], & + i__1, &ierr); + +/* Zero out above L */ + + i__1 = *m - 1; + i__2 = *m - 1; + slaset_("U", &i__1, &i__2, &c_b29, &c_b29, &a[(a_dim1 << 1) + + 1], lda); + ie = 1; + itauq = ie + *m; + itaup = itauq + *m; + nwork = itaup + *m; + +/* + Bidiagonalize L in A + (Workspace: need 4*M, prefer 3*M+2*M*NB) +*/ + + i__1 = *lwork - nwork + 1; + sgebrd_(m, m, &a[a_offset], lda, &s[1], &work[ie], &work[ + itauq], &work[itaup], &work[nwork], &i__1, &ierr); + nwork = ie + *m; + +/* + Perform bidiagonal SVD, computing singular values only + (Workspace: need M+BDSPAC) +*/ + + sbdsdc_("U", "N", m, &s[1], &work[ie], dum, &c__1, dum, &c__1, + dum, idum, &work[nwork], &iwork[1], info); + + } else if (wntqo) { + +/* + Path 2t (N much larger than M, JOBZ='O') + M right singular vectors to be overwritten on A and + M left singular vectors to be computed in U +*/ + + ivt = 1; + +/* IVT is M by M */ + + il = ivt + *m * *m; + if (*lwork >= *m * *n + *m * *m + *m * 3 + bdspac) { + +/* WORK(IL) is M by N */ + + ldwrkl = *m; + chunk = *n; + } else { + ldwrkl = *m; + chunk = (*lwork - *m * *m) / *m; + } + itau = il + ldwrkl * *m; + nwork = itau + *m; + +/* + Compute A=L*Q + (Workspace: need M*M+2*M, prefer M*M+M+M*NB) +*/ + + i__1 = *lwork - nwork + 1; + sgelqf_(m, n, &a[a_offset], lda, &work[itau], &work[nwork], & + i__1, &ierr); + +/* Copy L to WORK(IL), zeroing about above it */ + + slacpy_("L", m, m, &a[a_offset], lda, &work[il], &ldwrkl); + i__1 = *m - 1; + i__2 = *m - 1; + slaset_("U", &i__1, &i__2, &c_b29, &c_b29, &work[il + ldwrkl], + &ldwrkl); + +/* + Generate Q in A + (Workspace: need M*M+2*M, prefer M*M+M+M*NB) +*/ + + i__1 = *lwork - nwork + 1; + sorglq_(m, n, m, &a[a_offset], lda, &work[itau], &work[nwork], + &i__1, &ierr); + ie = itau; + itauq = ie + *m; + itaup = itauq + *m; + nwork = itaup + *m; + +/* + Bidiagonalize L in WORK(IL) + (Workspace: need M*M+4*M, prefer M*M+3*M+2*M*NB) +*/ + + i__1 = *lwork - nwork + 1; + sgebrd_(m, m, &work[il], &ldwrkl, &s[1], &work[ie], &work[ + itauq], &work[itaup], &work[nwork], &i__1, &ierr); + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagonal matrix in U, and computing right singular + vectors of bidiagonal matrix in WORK(IVT) + (Workspace: need M+M*M+BDSPAC) +*/ + + sbdsdc_("U", "I", m, &s[1], &work[ie], &u[u_offset], ldu, & + work[ivt], m, dum, idum, &work[nwork], &iwork[1], + info); + +/* + Overwrite U by left singular vectors of L and WORK(IVT) + by right singular vectors of L + (Workspace: need 2*M*M+3*M, prefer 2*M*M+2*M+M*NB) +*/ + + i__1 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", m, m, m, &work[il], &ldwrkl, &work[ + itauq], &u[u_offset], ldu, &work[nwork], &i__1, &ierr); + i__1 = *lwork - nwork + 1; + sormbr_("P", "R", "T", m, m, m, &work[il], &ldwrkl, &work[ + itaup], &work[ivt], m, &work[nwork], &i__1, &ierr); + +/* + Multiply right singular vectors of L in WORK(IVT) by Q + in A, storing result in WORK(IL) and copying to A + (Workspace: need 2*M*M, prefer M*M+M*N) +*/ + + i__1 = *n; + i__2 = chunk; + for (i__ = 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += + i__2) { +/* Computing MIN */ + i__3 = *n - i__ + 1; + blk = min(i__3,chunk); + sgemm_("N", "N", m, &blk, m, &c_b15, &work[ivt], m, &a[ + i__ * a_dim1 + 1], lda, &c_b29, &work[il], & + ldwrkl); + slacpy_("F", m, &blk, &work[il], &ldwrkl, &a[i__ * a_dim1 + + 1], lda); +/* L30: */ + } + + } else if (wntqs) { + +/* + Path 3t (N much larger than M, JOBZ='S') + M right singular vectors to be computed in VT and + M left singular vectors to be computed in U +*/ + + il = 1; + +/* WORK(IL) is M by M */ + + ldwrkl = *m; + itau = il + ldwrkl * *m; + nwork = itau + *m; + +/* + Compute A=L*Q + (Workspace: need M*M+2*M, prefer M*M+M+M*NB) +*/ + + i__2 = *lwork - nwork + 1; + sgelqf_(m, n, &a[a_offset], lda, &work[itau], &work[nwork], & + i__2, &ierr); + +/* Copy L to WORK(IL), zeroing out above it */ + + slacpy_("L", m, m, &a[a_offset], lda, &work[il], &ldwrkl); + i__2 = *m - 1; + i__1 = *m - 1; + slaset_("U", &i__2, &i__1, &c_b29, &c_b29, &work[il + ldwrkl], + &ldwrkl); + +/* + Generate Q in A + (Workspace: need M*M+2*M, prefer M*M+M+M*NB) +*/ + + i__2 = *lwork - nwork + 1; + sorglq_(m, n, m, &a[a_offset], lda, &work[itau], &work[nwork], + &i__2, &ierr); + ie = itau; + itauq = ie + *m; + itaup = itauq + *m; + nwork = itaup + *m; + +/* + Bidiagonalize L in WORK(IU), copying result to U + (Workspace: need M*M+4*M, prefer M*M+3*M+2*M*NB) +*/ + + i__2 = *lwork - nwork + 1; + sgebrd_(m, m, &work[il], &ldwrkl, &s[1], &work[ie], &work[ + itauq], &work[itaup], &work[nwork], &i__2, &ierr); + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagonal matrix in U and computing right singular + vectors of bidiagonal matrix in VT + (Workspace: need M+BDSPAC) +*/ + + sbdsdc_("U", "I", m, &s[1], &work[ie], &u[u_offset], ldu, &vt[ + vt_offset], ldvt, dum, idum, &work[nwork], &iwork[1], + info); + +/* + Overwrite U by left singular vectors of L and VT + by right singular vectors of L + (Workspace: need M*M+3*M, prefer M*M+2*M+M*NB) +*/ + + i__2 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", m, m, m, &work[il], &ldwrkl, &work[ + itauq], &u[u_offset], ldu, &work[nwork], &i__2, &ierr); + i__2 = *lwork - nwork + 1; + sormbr_("P", "R", "T", m, m, m, &work[il], &ldwrkl, &work[ + itaup], &vt[vt_offset], ldvt, &work[nwork], &i__2, & + ierr); + +/* + Multiply right singular vectors of L in WORK(IL) by + Q in A, storing result in VT + (Workspace: need M*M) +*/ + + slacpy_("F", m, m, &vt[vt_offset], ldvt, &work[il], &ldwrkl); + sgemm_("N", "N", m, n, m, &c_b15, &work[il], &ldwrkl, &a[ + a_offset], lda, &c_b29, &vt[vt_offset], ldvt); + + } else if (wntqa) { + +/* + Path 4t (N much larger than M, JOBZ='A') + N right singular vectors to be computed in VT and + M left singular vectors to be computed in U +*/ + + ivt = 1; + +/* WORK(IVT) is M by M */ + + ldwkvt = *m; + itau = ivt + ldwkvt * *m; + nwork = itau + *m; + +/* + Compute A=L*Q, copying result to VT + (Workspace: need M*M+2*M, prefer M*M+M+M*NB) +*/ + + i__2 = *lwork - nwork + 1; + sgelqf_(m, n, &a[a_offset], lda, &work[itau], &work[nwork], & + i__2, &ierr); + slacpy_("U", m, n, &a[a_offset], lda, &vt[vt_offset], ldvt); + +/* + Generate Q in VT + (Workspace: need M*M+2*M, prefer M*M+M+M*NB) +*/ + + i__2 = *lwork - nwork + 1; + sorglq_(n, n, m, &vt[vt_offset], ldvt, &work[itau], &work[ + nwork], &i__2, &ierr); + +/* Produce L in A, zeroing out other entries */ + + i__2 = *m - 1; + i__1 = *m - 1; + slaset_("U", &i__2, &i__1, &c_b29, &c_b29, &a[(a_dim1 << 1) + + 1], lda); + ie = itau; + itauq = ie + *m; + itaup = itauq + *m; + nwork = itaup + *m; + +/* + Bidiagonalize L in A + (Workspace: need M*M+4*M, prefer M*M+3*M+2*M*NB) +*/ + + i__2 = *lwork - nwork + 1; + sgebrd_(m, m, &a[a_offset], lda, &s[1], &work[ie], &work[ + itauq], &work[itaup], &work[nwork], &i__2, &ierr); + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagonal matrix in U and computing right singular + vectors of bidiagonal matrix in WORK(IVT) + (Workspace: need M+M*M+BDSPAC) +*/ + + sbdsdc_("U", "I", m, &s[1], &work[ie], &u[u_offset], ldu, & + work[ivt], &ldwkvt, dum, idum, &work[nwork], &iwork[1] + , info); + +/* + Overwrite U by left singular vectors of L and WORK(IVT) + by right singular vectors of L + (Workspace: need M*M+3*M, prefer M*M+2*M+M*NB) +*/ + + i__2 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", m, m, m, &a[a_offset], lda, &work[ + itauq], &u[u_offset], ldu, &work[nwork], &i__2, &ierr); + i__2 = *lwork - nwork + 1; + sormbr_("P", "R", "T", m, m, m, &a[a_offset], lda, &work[ + itaup], &work[ivt], &ldwkvt, &work[nwork], &i__2, & + ierr); + +/* + Multiply right singular vectors of L in WORK(IVT) by + Q in VT, storing result in A + (Workspace: need M*M) +*/ + + sgemm_("N", "N", m, n, m, &c_b15, &work[ivt], &ldwkvt, &vt[ + vt_offset], ldvt, &c_b29, &a[a_offset], lda); + +/* Copy right singular vectors of A from A to VT */ + + slacpy_("F", m, n, &a[a_offset], lda, &vt[vt_offset], ldvt); + + } + + } else { + +/* + N .LT. MNTHR + + Path 5t (N greater than M, but not much larger) + Reduce to bidiagonal form without LQ decomposition +*/ + + ie = 1; + itauq = ie + *m; + itaup = itauq + *m; + nwork = itaup + *m; + +/* + Bidiagonalize A + (Workspace: need 3*M+N, prefer 3*M+(M+N)*NB) +*/ + + i__2 = *lwork - nwork + 1; + sgebrd_(m, n, &a[a_offset], lda, &s[1], &work[ie], &work[itauq], & + work[itaup], &work[nwork], &i__2, &ierr); + if (wntqn) { + +/* + Perform bidiagonal SVD, only computing singular values + (Workspace: need M+BDSPAC) +*/ + + sbdsdc_("L", "N", m, &s[1], &work[ie], dum, &c__1, dum, &c__1, + dum, idum, &work[nwork], &iwork[1], info); + } else if (wntqo) { + ldwkvt = *m; + ivt = nwork; + if (*lwork >= *m * *n + *m * 3 + bdspac) { + +/* WORK( IVT ) is M by N */ + + slaset_("F", m, n, &c_b29, &c_b29, &work[ivt], &ldwkvt); + nwork = ivt + ldwkvt * *n; + } else { + +/* WORK( IVT ) is M by M */ + + nwork = ivt + ldwkvt * *m; + il = nwork; + +/* WORK(IL) is M by CHUNK */ + + chunk = (*lwork - *m * *m - *m * 3) / *m; + } + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagonal matrix in U and computing right singular + vectors of bidiagonal matrix in WORK(IVT) + (Workspace: need M*M+BDSPAC) +*/ + + sbdsdc_("L", "I", m, &s[1], &work[ie], &u[u_offset], ldu, & + work[ivt], &ldwkvt, dum, idum, &work[nwork], &iwork[1] + , info); + +/* + Overwrite U by left singular vectors of A + (Workspace: need M*M+2*M, prefer M*M+M+M*NB) +*/ + + i__2 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", m, m, n, &a[a_offset], lda, &work[ + itauq], &u[u_offset], ldu, &work[nwork], &i__2, &ierr); + + if (*lwork >= *m * *n + *m * 3 + bdspac) { + +/* + Overwrite WORK(IVT) by left singular vectors of A + (Workspace: need M*M+2*M, prefer M*M+M+M*NB) +*/ + + i__2 = *lwork - nwork + 1; + sormbr_("P", "R", "T", m, n, m, &a[a_offset], lda, &work[ + itaup], &work[ivt], &ldwkvt, &work[nwork], &i__2, + &ierr); + +/* Copy right singular vectors of A from WORK(IVT) to A */ + + slacpy_("F", m, n, &work[ivt], &ldwkvt, &a[a_offset], lda); + } else { + +/* + Generate P**T in A + (Workspace: need M*M+2*M, prefer M*M+M+M*NB) +*/ + + i__2 = *lwork - nwork + 1; + sorgbr_("P", m, n, m, &a[a_offset], lda, &work[itaup], & + work[nwork], &i__2, &ierr); + +/* + Multiply Q in A by right singular vectors of + bidiagonal matrix in WORK(IVT), storing result in + WORK(IL) and copying to A + (Workspace: need 2*M*M, prefer M*M+M*N) +*/ + + i__2 = *n; + i__1 = chunk; + for (i__ = 1; i__1 < 0 ? i__ >= i__2 : i__ <= i__2; i__ += + i__1) { +/* Computing MIN */ + i__3 = *n - i__ + 1; + blk = min(i__3,chunk); + sgemm_("N", "N", m, &blk, m, &c_b15, &work[ivt], & + ldwkvt, &a[i__ * a_dim1 + 1], lda, &c_b29, & + work[il], m); + slacpy_("F", m, &blk, &work[il], m, &a[i__ * a_dim1 + + 1], lda); +/* L40: */ + } + } + } else if (wntqs) { + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagonal matrix in U and computing right singular + vectors of bidiagonal matrix in VT + (Workspace: need M+BDSPAC) +*/ + + slaset_("F", m, n, &c_b29, &c_b29, &vt[vt_offset], ldvt); + sbdsdc_("L", "I", m, &s[1], &work[ie], &u[u_offset], ldu, &vt[ + vt_offset], ldvt, dum, idum, &work[nwork], &iwork[1], + info); + +/* + Overwrite U by left singular vectors of A and VT + by right singular vectors of A + (Workspace: need 3*M, prefer 2*M+M*NB) +*/ + + i__1 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", m, m, n, &a[a_offset], lda, &work[ + itauq], &u[u_offset], ldu, &work[nwork], &i__1, &ierr); + i__1 = *lwork - nwork + 1; + sormbr_("P", "R", "T", m, n, m, &a[a_offset], lda, &work[ + itaup], &vt[vt_offset], ldvt, &work[nwork], &i__1, & + ierr); + } else if (wntqa) { + +/* + Perform bidiagonal SVD, computing left singular vectors + of bidiagonal matrix in U and computing right singular + vectors of bidiagonal matrix in VT + (Workspace: need M+BDSPAC) +*/ + + slaset_("F", n, n, &c_b29, &c_b29, &vt[vt_offset], ldvt); + sbdsdc_("L", "I", m, &s[1], &work[ie], &u[u_offset], ldu, &vt[ + vt_offset], ldvt, dum, idum, &work[nwork], &iwork[1], + info); + +/* Set the right corner of VT to identity matrix */ + + i__1 = *n - *m; + i__2 = *n - *m; + slaset_("F", &i__1, &i__2, &c_b29, &c_b15, &vt[*m + 1 + (*m + + 1) * vt_dim1], ldvt); + +/* + Overwrite U by left singular vectors of A and VT + by right singular vectors of A + (Workspace: need 2*M+N, prefer 2*M+N*NB) +*/ + + i__1 = *lwork - nwork + 1; + sormbr_("Q", "L", "N", m, m, n, &a[a_offset], lda, &work[ + itauq], &u[u_offset], ldu, &work[nwork], &i__1, &ierr); + i__1 = *lwork - nwork + 1; + sormbr_("P", "R", "T", n, n, m, &a[a_offset], lda, &work[ + itaup], &vt[vt_offset], ldvt, &work[nwork], &i__1, & + ierr); + } + + } + + } + +/* Undo scaling if necessary */ + + if (iscl == 1) { + if (anrm > bignum) { + slascl_("G", &c__0, &c__0, &bignum, &anrm, &minmn, &c__1, &s[1], & + minmn, &ierr); + } + if (anrm < smlnum) { + slascl_("G", &c__0, &c__0, &smlnum, &anrm, &minmn, &c__1, &s[1], & + minmn, &ierr); + } + } + +/* Return optimal workspace in WORK(1) */ + + work[1] = (real) maxwrk; + + return 0; + +/* End of SGESDD */ + +} /* sgesdd_ */ + +/* Subroutine */ int sgesv_(integer *n, integer *nrhs, real *a, integer *lda, + integer *ipiv, real *b, integer *ldb, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, b_dim1, b_offset, i__1; + + /* Local variables */ + extern /* Subroutine */ int xerbla_(char *, integer *), sgetrf_( + integer *, integer *, real *, integer *, integer *, integer *), + sgetrs_(char *, integer *, integer *, real *, integer *, integer * + , real *, integer *, integer *); + + +/* + -- LAPACK driver routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + March 31, 1993 + + + Purpose + ======= + + SGESV computes the solution to a real system of linear equations + A * X = B, + where A is an N-by-N matrix and X and B are N-by-NRHS matrices. + + The LU decomposition with partial pivoting and row interchanges is + used to factor A as + A = P * L * U, + where P is a permutation matrix, L is unit lower triangular, and U is + upper triangular. The factored form of A is then used to solve the + system of equations A * X = B. + + Arguments + ========= + + N (input) INTEGER + The number of linear equations, i.e., the order of the + matrix A. N >= 0. + + NRHS (input) INTEGER + The number of right hand sides, i.e., the number of columns + of the matrix B. NRHS >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the N-by-N coefficient matrix A. + On exit, the factors L and U from the factorization + A = P*L*U; the unit diagonal elements of L are not stored. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + IPIV (output) INTEGER array, dimension (N) + The pivot indices that define the permutation matrix P; + row i of the matrix was interchanged with row IPIV(i). + + B (input/output) REAL array, dimension (LDB,NRHS) + On entry, the N-by-NRHS matrix of right hand side matrix B. + On exit, if INFO = 0, the N-by-NRHS solution matrix X. + + LDB (input) INTEGER + The leading dimension of the array B. LDB >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + > 0: if INFO = i, U(i,i) is exactly zero. The factorization + has been completed, but the factor U is exactly + singular, so the solution could not be computed. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --ipiv; + b_dim1 = *ldb; + b_offset = 1 + b_dim1; + b -= b_offset; + + /* Function Body */ + *info = 0; + if (*n < 0) { + *info = -1; + } else if (*nrhs < 0) { + *info = -2; + } else if (*lda < max(1,*n)) { + *info = -4; + } else if (*ldb < max(1,*n)) { + *info = -7; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGESV ", &i__1); + return 0; + } + +/* Compute the LU factorization of A. */ + + sgetrf_(n, n, &a[a_offset], lda, &ipiv[1], info); + if (*info == 0) { + +/* Solve the system A*X = B, overwriting B with X. */ + + sgetrs_("No transpose", n, nrhs, &a[a_offset], lda, &ipiv[1], &b[ + b_offset], ldb, info); + } + return 0; + +/* End of SGESV */ + +} /* sgesv_ */ + +/* Subroutine */ int sgetf2_(integer *m, integer *n, real *a, integer *lda, + integer *ipiv, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + real r__1; + + /* Local variables */ + static integer j, jp; + extern /* Subroutine */ int sger_(integer *, integer *, real *, real *, + integer *, real *, integer *, real *, integer *), sscal_(integer * + , real *, real *, integer *), sswap_(integer *, real *, integer *, + real *, integer *), xerbla_(char *, integer *); + extern integer isamax_(integer *, real *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1992 + + + Purpose + ======= + + SGETF2 computes an LU factorization of a general m-by-n matrix A + using partial pivoting with row interchanges. + + The factorization has the form + A = P * L * U + where P is a permutation matrix, L is lower triangular with unit + diagonal elements (lower trapezoidal if m > n), and U is upper + triangular (upper trapezoidal if m < n). + + This is the right-looking Level 2 BLAS version of the algorithm. + + Arguments + ========= + + M (input) INTEGER + The number of rows of the matrix A. M >= 0. + + N (input) INTEGER + The number of columns of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the m by n matrix to be factored. + On exit, the factors L and U from the factorization + A = P*L*U; the unit diagonal elements of L are not stored. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + IPIV (output) INTEGER array, dimension (min(M,N)) + The pivot indices; for 1 <= i <= min(M,N), row i of the + matrix was interchanged with row IPIV(i). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -k, the k-th argument had an illegal value + > 0: if INFO = k, U(k,k) is exactly zero. The factorization + has been completed, but the factor U is exactly + singular, and division by zero will occur if it is used + to solve a system of equations. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --ipiv; + + /* Function Body */ + *info = 0; + if (*m < 0) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*m)) { + *info = -4; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGETF2", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0) { + return 0; + } + + i__1 = min(*m,*n); + for (j = 1; j <= i__1; ++j) { + +/* Find pivot and test for singularity. */ + + i__2 = *m - j + 1; + jp = j - 1 + isamax_(&i__2, &a[j + j * a_dim1], &c__1); + ipiv[j] = jp; + if (a[jp + j * a_dim1] != 0.f) { + +/* Apply the interchange to columns 1:N. */ + + if (jp != j) { + sswap_(n, &a[j + a_dim1], lda, &a[jp + a_dim1], lda); + } + +/* Compute elements J+1:M of J-th column. */ + + if (j < *m) { + i__2 = *m - j; + r__1 = 1.f / a[j + j * a_dim1]; + sscal_(&i__2, &r__1, &a[j + 1 + j * a_dim1], &c__1); + } + + } else if (*info == 0) { + + *info = j; + } + + if (j < min(*m,*n)) { + +/* Update trailing submatrix. */ + + i__2 = *m - j; + i__3 = *n - j; + sger_(&i__2, &i__3, &c_b151, &a[j + 1 + j * a_dim1], &c__1, &a[j + + (j + 1) * a_dim1], lda, &a[j + 1 + (j + 1) * a_dim1], + lda); + } +/* L10: */ + } + return 0; + +/* End of SGETF2 */ + +} /* sgetf2_ */ + +/* Subroutine */ int sgetrf_(integer *m, integer *n, real *a, integer *lda, + integer *ipiv, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3, i__4, i__5; + + /* Local variables */ + static integer i__, j, jb, nb, iinfo; + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *), strsm_(char *, char *, char *, + char *, integer *, integer *, real *, real *, integer *, real *, + integer *), sgetf2_(integer *, + integer *, real *, integer *, integer *, integer *), xerbla_(char + *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slaswp_(integer *, real *, integer *, integer + *, integer *, integer *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + March 31, 1993 + + + Purpose + ======= + + SGETRF computes an LU factorization of a general M-by-N matrix A + using partial pivoting with row interchanges. + + The factorization has the form + A = P * L * U + where P is a permutation matrix, L is lower triangular with unit + diagonal elements (lower trapezoidal if m > n), and U is upper + triangular (upper trapezoidal if m < n). + + This is the right-looking Level 3 BLAS version of the algorithm. + + Arguments + ========= + + M (input) INTEGER + The number of rows of the matrix A. M >= 0. + + N (input) INTEGER + The number of columns of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the M-by-N matrix to be factored. + On exit, the factors L and U from the factorization + A = P*L*U; the unit diagonal elements of L are not stored. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + IPIV (output) INTEGER array, dimension (min(M,N)) + The pivot indices; for 1 <= i <= min(M,N), row i of the + matrix was interchanged with row IPIV(i). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + > 0: if INFO = i, U(i,i) is exactly zero. The factorization + has been completed, but the factor U is exactly + singular, and division by zero will occur if it is used + to solve a system of equations. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --ipiv; + + /* Function Body */ + *info = 0; + if (*m < 0) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*m)) { + *info = -4; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGETRF", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0) { + return 0; + } + +/* Determine the block size for this environment. */ + + nb = ilaenv_(&c__1, "SGETRF", " ", m, n, &c_n1, &c_n1, (ftnlen)6, (ftnlen) + 1); + if (nb <= 1 || nb >= min(*m,*n)) { + +/* Use unblocked code. */ + + sgetf2_(m, n, &a[a_offset], lda, &ipiv[1], info); + } else { + +/* Use blocked code. */ + + i__1 = min(*m,*n); + i__2 = nb; + for (j = 1; i__2 < 0 ? j >= i__1 : j <= i__1; j += i__2) { +/* Computing MIN */ + i__3 = min(*m,*n) - j + 1; + jb = min(i__3,nb); + +/* + Factor diagonal and subdiagonal blocks and test for exact + singularity. +*/ + + i__3 = *m - j + 1; + sgetf2_(&i__3, &jb, &a[j + j * a_dim1], lda, &ipiv[j], &iinfo); + +/* Adjust INFO and the pivot indices. */ + + if (*info == 0 && iinfo > 0) { + *info = iinfo + j - 1; + } +/* Computing MIN */ + i__4 = *m, i__5 = j + jb - 1; + i__3 = min(i__4,i__5); + for (i__ = j; i__ <= i__3; ++i__) { + ipiv[i__] = j - 1 + ipiv[i__]; +/* L10: */ + } + +/* Apply interchanges to columns 1:J-1. */ + + i__3 = j - 1; + i__4 = j + jb - 1; + slaswp_(&i__3, &a[a_offset], lda, &j, &i__4, &ipiv[1], &c__1); + + if (j + jb <= *n) { + +/* Apply interchanges to columns J+JB:N. */ + + i__3 = *n - j - jb + 1; + i__4 = j + jb - 1; + slaswp_(&i__3, &a[(j + jb) * a_dim1 + 1], lda, &j, &i__4, & + ipiv[1], &c__1); + +/* Compute block row of U. */ + + i__3 = *n - j - jb + 1; + strsm_("Left", "Lower", "No transpose", "Unit", &jb, &i__3, & + c_b15, &a[j + j * a_dim1], lda, &a[j + (j + jb) * + a_dim1], lda); + if (j + jb <= *m) { + +/* Update trailing submatrix. */ + + i__3 = *m - j - jb + 1; + i__4 = *n - j - jb + 1; + sgemm_("No transpose", "No transpose", &i__3, &i__4, &jb, + &c_b151, &a[j + jb + j * a_dim1], lda, &a[j + (j + + jb) * a_dim1], lda, &c_b15, &a[j + jb + (j + jb) + * a_dim1], lda); + } + } +/* L20: */ + } + } + return 0; + +/* End of SGETRF */ + +} /* sgetrf_ */ + +/* Subroutine */ int sgetrs_(char *trans, integer *n, integer *nrhs, real *a, + integer *lda, integer *ipiv, real *b, integer *ldb, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, b_dim1, b_offset, i__1; + + /* Local variables */ + extern logical lsame_(char *, char *); + extern /* Subroutine */ int strsm_(char *, char *, char *, char *, + integer *, integer *, real *, real *, integer *, real *, integer * + ), xerbla_(char *, integer *); + static logical notran; + extern /* Subroutine */ int slaswp_(integer *, real *, integer *, integer + *, integer *, integer *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + March 31, 1993 + + + Purpose + ======= + + SGETRS solves a system of linear equations + A * X = B or A' * X = B + with a general N-by-N matrix A using the LU factorization computed + by SGETRF. + + Arguments + ========= + + TRANS (input) CHARACTER*1 + Specifies the form of the system of equations: + = 'N': A * X = B (No transpose) + = 'T': A'* X = B (Transpose) + = 'C': A'* X = B (Conjugate transpose = Transpose) + + N (input) INTEGER + The order of the matrix A. N >= 0. + + NRHS (input) INTEGER + The number of right hand sides, i.e., the number of columns + of the matrix B. NRHS >= 0. + + A (input) REAL array, dimension (LDA,N) + The factors L and U from the factorization A = P*L*U + as computed by SGETRF. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + IPIV (input) INTEGER array, dimension (N) + The pivot indices from SGETRF; for 1<=i<=N, row i of the + matrix was interchanged with row IPIV(i). + + B (input/output) REAL array, dimension (LDB,NRHS) + On entry, the right hand side matrix B. + On exit, the solution matrix X. + + LDB (input) INTEGER + The leading dimension of the array B. LDB >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --ipiv; + b_dim1 = *ldb; + b_offset = 1 + b_dim1; + b -= b_offset; + + /* Function Body */ + *info = 0; + notran = lsame_(trans, "N"); + if (! notran && ! lsame_(trans, "T") && ! lsame_( + trans, "C")) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*nrhs < 0) { + *info = -3; + } else if (*lda < max(1,*n)) { + *info = -5; + } else if (*ldb < max(1,*n)) { + *info = -8; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SGETRS", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0 || *nrhs == 0) { + return 0; + } + + if (notran) { + +/* + Solve A * X = B. + + Apply row interchanges to the right hand sides. +*/ + + slaswp_(nrhs, &b[b_offset], ldb, &c__1, n, &ipiv[1], &c__1); + +/* Solve L*X = B, overwriting B with X. */ + + strsm_("Left", "Lower", "No transpose", "Unit", n, nrhs, &c_b15, &a[ + a_offset], lda, &b[b_offset], ldb); + +/* Solve U*X = B, overwriting B with X. */ + + strsm_("Left", "Upper", "No transpose", "Non-unit", n, nrhs, &c_b15, & + a[a_offset], lda, &b[b_offset], ldb); + } else { + +/* + Solve A' * X = B. + + Solve U'*X = B, overwriting B with X. +*/ + + strsm_("Left", "Upper", "Transpose", "Non-unit", n, nrhs, &c_b15, &a[ + a_offset], lda, &b[b_offset], ldb); + +/* Solve L'*X = B, overwriting B with X. */ + + strsm_("Left", "Lower", "Transpose", "Unit", n, nrhs, &c_b15, &a[ + a_offset], lda, &b[b_offset], ldb); + +/* Apply row interchanges to the solution vectors. */ + + slaswp_(nrhs, &b[b_offset], ldb, &c__1, n, &ipiv[1], &c_n1); + } + + return 0; + +/* End of SGETRS */ + +} /* sgetrs_ */ + +/* Subroutine */ int shseqr_(char *job, char *compz, integer *n, integer *ilo, + integer *ihi, real *h__, integer *ldh, real *wr, real *wi, real *z__, + integer *ldz, real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + address a__1[2]; + integer h_dim1, h_offset, z_dim1, z_offset, i__1, i__2, i__3[2], i__4, + i__5; + real r__1, r__2; + char ch__1[2]; + + /* Builtin functions */ + /* Subroutine */ int s_cat(char *, char **, integer *, integer *, ftnlen); + + /* Local variables */ + static integer i__, j, k, l; + static real s[225] /* was [15][15] */, v[16]; + static integer i1, i2, ii, nh, nr, ns, nv; + static real vv[16]; + static integer itn; + static real tau; + static integer its; + static real ulp, tst1; + static integer maxb; + static real absw; + static integer ierr; + static real unfl, temp, ovfl; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *); + static integer itemp; + extern /* Subroutine */ int sgemv_(char *, integer *, integer *, real *, + real *, integer *, real *, integer *, real *, real *, integer *); + static logical initz, wantt; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *); + static logical wantz; + extern doublereal slapy2_(real *, real *); + extern /* Subroutine */ int slabad_(real *, real *); + extern doublereal slamch_(char *); + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slarfg_(integer *, real *, real *, integer *, + real *); + extern integer isamax_(integer *, real *, integer *); + extern doublereal slanhs_(char *, integer *, real *, integer *, real *); + extern /* Subroutine */ int slahqr_(logical *, logical *, integer *, + integer *, integer *, real *, integer *, real *, real *, integer * + , integer *, real *, integer *, integer *), slacpy_(char *, + integer *, integer *, real *, integer *, real *, integer *), slaset_(char *, integer *, integer *, real *, real *, + real *, integer *), slarfx_(char *, integer *, integer *, + real *, real *, real *, integer *, real *); + static real smlnum; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SHSEQR computes the eigenvalues of a real upper Hessenberg matrix H + and, optionally, the matrices T and Z from the Schur decomposition + H = Z T Z**T, where T is an upper quasi-triangular matrix (the Schur + form), and Z is the orthogonal matrix of Schur vectors. + + Optionally Z may be postmultiplied into an input orthogonal matrix Q, + so that this routine can give the Schur factorization of a matrix A + which has been reduced to the Hessenberg form H by the orthogonal + matrix Q: A = Q*H*Q**T = (QZ)*T*(QZ)**T. + + Arguments + ========= + + JOB (input) CHARACTER*1 + = 'E': compute eigenvalues only; + = 'S': compute eigenvalues and the Schur form T. + + COMPZ (input) CHARACTER*1 + = 'N': no Schur vectors are computed; + = 'I': Z is initialized to the unit matrix and the matrix Z + of Schur vectors of H is returned; + = 'V': Z must contain an orthogonal matrix Q on entry, and + the product Q*Z is returned. + + N (input) INTEGER + The order of the matrix H. N >= 0. + + ILO (input) INTEGER + IHI (input) INTEGER + It is assumed that H is already upper triangular in rows + and columns 1:ILO-1 and IHI+1:N. ILO and IHI are normally + set by a previous call to SGEBAL, and then passed to SGEHRD + when the matrix output by SGEBAL is reduced to Hessenberg + form. Otherwise ILO and IHI should be set to 1 and N + respectively. + 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. + + H (input/output) REAL array, dimension (LDH,N) + On entry, the upper Hessenberg matrix H. + On exit, if JOB = 'S', H contains the upper quasi-triangular + matrix T from the Schur decomposition (the Schur form); + 2-by-2 diagonal blocks (corresponding to complex conjugate + pairs of eigenvalues) are returned in standard form, with + H(i,i) = H(i+1,i+1) and H(i+1,i)*H(i,i+1) < 0. If JOB = 'E', + the contents of H are unspecified on exit. + + LDH (input) INTEGER + The leading dimension of the array H. LDH >= max(1,N). + + WR (output) REAL array, dimension (N) + WI (output) REAL array, dimension (N) + The real and imaginary parts, respectively, of the computed + eigenvalues. If two eigenvalues are computed as a complex + conjugate pair, they are stored in consecutive elements of + WR and WI, say the i-th and (i+1)th, with WI(i) > 0 and + WI(i+1) < 0. If JOB = 'S', the eigenvalues are stored in the + same order as on the diagonal of the Schur form returned in + H, with WR(i) = H(i,i) and, if H(i:i+1,i:i+1) is a 2-by-2 + diagonal block, WI(i) = sqrt(H(i+1,i)*H(i,i+1)) and + WI(i+1) = -WI(i). + + Z (input/output) REAL array, dimension (LDZ,N) + If COMPZ = 'N': Z is not referenced. + If COMPZ = 'I': on entry, Z need not be set, and on exit, Z + contains the orthogonal matrix Z of the Schur vectors of H. + If COMPZ = 'V': on entry Z must contain an N-by-N matrix Q, + which is assumed to be equal to the unit matrix except for + the submatrix Z(ILO:IHI,ILO:IHI); on exit Z contains Q*Z. + Normally Q is the orthogonal matrix generated by SORGHR after + the call to SGEHRD which formed the Hessenberg matrix H. + + LDZ (input) INTEGER + The leading dimension of the array Z. + LDZ >= max(1,N) if COMPZ = 'I' or 'V'; LDZ >= 1 otherwise. + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. LWORK >= max(1,N). + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + > 0: if INFO = i, SHSEQR failed to compute all of the + eigenvalues in a total of 30*(IHI-ILO+1) iterations; + elements 1:ilo-1 and i+1:n of WR and WI contain those + eigenvalues which have been successfully computed. + + ===================================================================== + + + Decode and test the input parameters +*/ + + /* Parameter adjustments */ + h_dim1 = *ldh; + h_offset = 1 + h_dim1; + h__ -= h_offset; + --wr; + --wi; + z_dim1 = *ldz; + z_offset = 1 + z_dim1; + z__ -= z_offset; + --work; + + /* Function Body */ + wantt = lsame_(job, "S"); + initz = lsame_(compz, "I"); + wantz = initz || lsame_(compz, "V"); + + *info = 0; + work[1] = (real) max(1,*n); + lquery = *lwork == -1; + if (! lsame_(job, "E") && ! wantt) { + *info = -1; + } else if (! lsame_(compz, "N") && ! wantz) { + *info = -2; + } else if (*n < 0) { + *info = -3; + } else if (*ilo < 1 || *ilo > max(1,*n)) { + *info = -4; + } else if (*ihi < min(*ilo,*n) || *ihi > *n) { + *info = -5; + } else if (*ldh < max(1,*n)) { + *info = -7; + } else if (*ldz < 1 || wantz && *ldz < max(1,*n)) { + *info = -11; + } else if (*lwork < max(1,*n) && ! lquery) { + *info = -13; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SHSEQR", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Initialize Z, if necessary */ + + if (initz) { + slaset_("Full", n, n, &c_b29, &c_b15, &z__[z_offset], ldz); + } + +/* Store the eigenvalues isolated by SGEBAL. */ + + i__1 = *ilo - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + wr[i__] = h__[i__ + i__ * h_dim1]; + wi[i__] = 0.f; +/* L10: */ + } + i__1 = *n; + for (i__ = *ihi + 1; i__ <= i__1; ++i__) { + wr[i__] = h__[i__ + i__ * h_dim1]; + wi[i__] = 0.f; +/* L20: */ + } + +/* Quick return if possible. */ + + if (*n == 0) { + return 0; + } + if (*ilo == *ihi) { + wr[*ilo] = h__[*ilo + *ilo * h_dim1]; + wi[*ilo] = 0.f; + return 0; + } + +/* + Set rows and columns ILO to IHI to zero below the first + subdiagonal. +*/ + + i__1 = *ihi - 2; + for (j = *ilo; j <= i__1; ++j) { + i__2 = *n; + for (i__ = j + 2; i__ <= i__2; ++i__) { + h__[i__ + j * h_dim1] = 0.f; +/* L30: */ + } +/* L40: */ + } + nh = *ihi - *ilo + 1; + +/* + Determine the order of the multi-shift QR algorithm to be used. + + Writing concatenation +*/ + i__3[0] = 1, a__1[0] = job; + i__3[1] = 1, a__1[1] = compz; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + ns = ilaenv_(&c__4, "SHSEQR", ch__1, n, ilo, ihi, &c_n1, (ftnlen)6, ( + ftnlen)2); +/* Writing concatenation */ + i__3[0] = 1, a__1[0] = job; + i__3[1] = 1, a__1[1] = compz; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + maxb = ilaenv_(&c__8, "SHSEQR", ch__1, n, ilo, ihi, &c_n1, (ftnlen)6, ( + ftnlen)2); + if (ns <= 2 || ns > nh || maxb >= nh) { + +/* Use the standard double-shift algorithm */ + + slahqr_(&wantt, &wantz, n, ilo, ihi, &h__[h_offset], ldh, &wr[1], &wi[ + 1], ilo, ihi, &z__[z_offset], ldz, info); + return 0; + } + maxb = max(3,maxb); +/* Computing MIN */ + i__1 = min(ns,maxb); + ns = min(i__1,15); + +/* + Now 2 < NS <= MAXB < NH. + + Set machine-dependent constants for the stopping criterion. + If norm(H) <= sqrt(OVFL), overflow should not occur. +*/ + + unfl = slamch_("Safe minimum"); + ovfl = 1.f / unfl; + slabad_(&unfl, &ovfl); + ulp = slamch_("Precision"); + smlnum = unfl * (nh / ulp); + +/* + I1 and I2 are the indices of the first row and last column of H + to which transformations must be applied. If eigenvalues only are + being computed, I1 and I2 are set inside the main loop. +*/ + + if (wantt) { + i1 = 1; + i2 = *n; + } + +/* ITN is the total number of multiple-shift QR iterations allowed. */ + + itn = nh * 30; + +/* + The main loop begins here. I is the loop index and decreases from + IHI to ILO in steps of at most MAXB. Each iteration of the loop + works with the active submatrix in rows and columns L to I. + Eigenvalues I+1 to IHI have already converged. Either L = ILO or + H(L,L-1) is negligible so that the matrix splits. +*/ + + i__ = *ihi; +L50: + l = *ilo; + if (i__ < *ilo) { + goto L170; + } + +/* + Perform multiple-shift QR iterations on rows and columns ILO to I + until a submatrix of order at most MAXB splits off at the bottom + because a subdiagonal element has become negligible. +*/ + + i__1 = itn; + for (its = 0; its <= i__1; ++its) { + +/* Look for a single small subdiagonal element. */ + + i__2 = l + 1; + for (k = i__; k >= i__2; --k) { + tst1 = (r__1 = h__[k - 1 + (k - 1) * h_dim1], dabs(r__1)) + (r__2 + = h__[k + k * h_dim1], dabs(r__2)); + if (tst1 == 0.f) { + i__4 = i__ - l + 1; + tst1 = slanhs_("1", &i__4, &h__[l + l * h_dim1], ldh, &work[1] + ); + } +/* Computing MAX */ + r__2 = ulp * tst1; + if ((r__1 = h__[k + (k - 1) * h_dim1], dabs(r__1)) <= dmax(r__2, + smlnum)) { + goto L70; + } +/* L60: */ + } +L70: + l = k; + if (l > *ilo) { + +/* H(L,L-1) is negligible. */ + + h__[l + (l - 1) * h_dim1] = 0.f; + } + +/* Exit from loop if a submatrix of order <= MAXB has split off. */ + + if (l >= i__ - maxb + 1) { + goto L160; + } + +/* + Now the active submatrix is in rows and columns L to I. If + eigenvalues only are being computed, only the active submatrix + need be transformed. +*/ + + if (! wantt) { + i1 = l; + i2 = i__; + } + + if (its == 20 || its == 30) { + +/* Exceptional shifts. */ + + i__2 = i__; + for (ii = i__ - ns + 1; ii <= i__2; ++ii) { + wr[ii] = ((r__1 = h__[ii + (ii - 1) * h_dim1], dabs(r__1)) + ( + r__2 = h__[ii + ii * h_dim1], dabs(r__2))) * 1.5f; + wi[ii] = 0.f; +/* L80: */ + } + } else { + +/* Use eigenvalues of trailing submatrix of order NS as shifts. */ + + slacpy_("Full", &ns, &ns, &h__[i__ - ns + 1 + (i__ - ns + 1) * + h_dim1], ldh, s, &c__15); + slahqr_(&c_false, &c_false, &ns, &c__1, &ns, s, &c__15, &wr[i__ - + ns + 1], &wi[i__ - ns + 1], &c__1, &ns, &z__[z_offset], + ldz, &ierr); + if (ierr > 0) { + +/* + If SLAHQR failed to compute all NS eigenvalues, use the + unconverged diagonal elements as the remaining shifts. +*/ + + i__2 = ierr; + for (ii = 1; ii <= i__2; ++ii) { + wr[i__ - ns + ii] = s[ii + ii * 15 - 16]; + wi[i__ - ns + ii] = 0.f; +/* L90: */ + } + } + } + +/* + Form the first column of (G-w(1)) (G-w(2)) . . . (G-w(ns)) + where G is the Hessenberg submatrix H(L:I,L:I) and w is + the vector of shifts (stored in WR and WI). The result is + stored in the local array V. +*/ + + v[0] = 1.f; + i__2 = ns + 1; + for (ii = 2; ii <= i__2; ++ii) { + v[ii - 1] = 0.f; +/* L100: */ + } + nv = 1; + i__2 = i__; + for (j = i__ - ns + 1; j <= i__2; ++j) { + if (wi[j] >= 0.f) { + if (wi[j] == 0.f) { + +/* real shift */ + + i__4 = nv + 1; + scopy_(&i__4, v, &c__1, vv, &c__1); + i__4 = nv + 1; + r__1 = -wr[j]; + sgemv_("No transpose", &i__4, &nv, &c_b15, &h__[l + l * + h_dim1], ldh, vv, &c__1, &r__1, v, &c__1); + ++nv; + } else if (wi[j] > 0.f) { + +/* complex conjugate pair of shifts */ + + i__4 = nv + 1; + scopy_(&i__4, v, &c__1, vv, &c__1); + i__4 = nv + 1; + r__1 = wr[j] * -2.f; + sgemv_("No transpose", &i__4, &nv, &c_b15, &h__[l + l * + h_dim1], ldh, v, &c__1, &r__1, vv, &c__1); + i__4 = nv + 1; + itemp = isamax_(&i__4, vv, &c__1); +/* Computing MAX */ + r__2 = (r__1 = vv[itemp - 1], dabs(r__1)); + temp = 1.f / dmax(r__2,smlnum); + i__4 = nv + 1; + sscal_(&i__4, &temp, vv, &c__1); + absw = slapy2_(&wr[j], &wi[j]); + temp = temp * absw * absw; + i__4 = nv + 2; + i__5 = nv + 1; + sgemv_("No transpose", &i__4, &i__5, &c_b15, &h__[l + l * + h_dim1], ldh, vv, &c__1, &temp, v, &c__1); + nv += 2; + } + +/* + Scale V(1:NV) so that max(abs(V(i))) = 1. If V is zero, + reset it to the unit vector. +*/ + + itemp = isamax_(&nv, v, &c__1); + temp = (r__1 = v[itemp - 1], dabs(r__1)); + if (temp == 0.f) { + v[0] = 1.f; + i__4 = nv; + for (ii = 2; ii <= i__4; ++ii) { + v[ii - 1] = 0.f; +/* L110: */ + } + } else { + temp = dmax(temp,smlnum); + r__1 = 1.f / temp; + sscal_(&nv, &r__1, v, &c__1); + } + } +/* L120: */ + } + +/* Multiple-shift QR step */ + + i__2 = i__ - 1; + for (k = l; k <= i__2; ++k) { + +/* + The first iteration of this loop determines a reflection G + from the vector V and applies it from left and right to H, + thus creating a nonzero bulge below the subdiagonal. + + Each subsequent iteration determines a reflection G to + restore the Hessenberg form in the (K-1)th column, and thus + chases the bulge one step toward the bottom of the active + submatrix. NR is the order of G. + + Computing MIN +*/ + i__4 = ns + 1, i__5 = i__ - k + 1; + nr = min(i__4,i__5); + if (k > l) { + scopy_(&nr, &h__[k + (k - 1) * h_dim1], &c__1, v, &c__1); + } + slarfg_(&nr, v, &v[1], &c__1, &tau); + if (k > l) { + h__[k + (k - 1) * h_dim1] = v[0]; + i__4 = i__; + for (ii = k + 1; ii <= i__4; ++ii) { + h__[ii + (k - 1) * h_dim1] = 0.f; +/* L130: */ + } + } + v[0] = 1.f; + +/* + Apply G from the left to transform the rows of the matrix in + columns K to I2. +*/ + + i__4 = i2 - k + 1; + slarfx_("Left", &nr, &i__4, v, &tau, &h__[k + k * h_dim1], ldh, & + work[1]); + +/* + Apply G from the right to transform the columns of the + matrix in rows I1 to min(K+NR,I). + + Computing MIN +*/ + i__5 = k + nr; + i__4 = min(i__5,i__) - i1 + 1; + slarfx_("Right", &i__4, &nr, v, &tau, &h__[i1 + k * h_dim1], ldh, + &work[1]); + + if (wantz) { + +/* Accumulate transformations in the matrix Z */ + + slarfx_("Right", &nh, &nr, v, &tau, &z__[*ilo + k * z_dim1], + ldz, &work[1]); + } +/* L140: */ + } + +/* L150: */ + } + +/* Failure to converge in remaining number of iterations */ + + *info = i__; + return 0; + +L160: + +/* + A submatrix of order <= MAXB in rows and columns L to I has split + off. Use the double-shift QR algorithm to handle it. +*/ + + slahqr_(&wantt, &wantz, n, &l, &i__, &h__[h_offset], ldh, &wr[1], &wi[1], + ilo, ihi, &z__[z_offset], ldz, info); + if (*info > 0) { + return 0; + } + +/* + Decrement number of remaining iterations, and return to start of + the main loop with a new value of I. +*/ + + itn -= its; + i__ = l - 1; + goto L50; + +L170: + work[1] = (real) max(1,*n); + return 0; + +/* End of SHSEQR */ + +} /* shseqr_ */ + +/* Subroutine */ int slabad_(real *small, real *large) +{ + /* Builtin functions */ + double r_lg10(real *), sqrt(doublereal); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLABAD takes as input the values computed by SLAMCH for underflow and + overflow, and returns the square root of each of these values if the + log of LARGE is sufficiently large. This subroutine is intended to + identify machines with a large exponent range, such as the Crays, and + redefine the underflow and overflow limits to be the square roots of + the values computed by SLAMCH. This subroutine is needed because + SLAMCH does not compensate for poor arithmetic in the upper half of + the exponent range, as is found on a Cray. + + Arguments + ========= + + SMALL (input/output) REAL + On entry, the underflow threshold as computed by SLAMCH. + On exit, if LOG10(LARGE) is sufficiently large, the square + root of SMALL, otherwise unchanged. + + LARGE (input/output) REAL + On entry, the overflow threshold as computed by SLAMCH. + On exit, if LOG10(LARGE) is sufficiently large, the square + root of LARGE, otherwise unchanged. + + ===================================================================== + + + If it looks like we're on a Cray, take the square root of + SMALL and LARGE to avoid overflow and underflow problems. +*/ + + if (r_lg10(large) > 2e3f) { + *small = sqrt(*small); + *large = sqrt(*large); + } + + return 0; + +/* End of SLABAD */ + +} /* slabad_ */ + +/* Subroutine */ int slabrd_(integer *m, integer *n, integer *nb, real *a, + integer *lda, real *d__, real *e, real *tauq, real *taup, real *x, + integer *ldx, real *y, integer *ldy) +{ + /* System generated locals */ + integer a_dim1, a_offset, x_dim1, x_offset, y_dim1, y_offset, i__1, i__2, + i__3; + + /* Local variables */ + static integer i__; + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *), + sgemv_(char *, integer *, integer *, real *, real *, integer *, + real *, integer *, real *, real *, integer *), slarfg_( + integer *, real *, real *, integer *, real *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SLABRD reduces the first NB rows and columns of a real general + m by n matrix A to upper or lower bidiagonal form by an orthogonal + transformation Q' * A * P, and returns the matrices X and Y which + are needed to apply the transformation to the unreduced part of A. + + If m >= n, A is reduced to upper bidiagonal form; if m < n, to lower + bidiagonal form. + + This is an auxiliary routine called by SGEBRD + + Arguments + ========= + + M (input) INTEGER + The number of rows in the matrix A. + + N (input) INTEGER + The number of columns in the matrix A. + + NB (input) INTEGER + The number of leading rows and columns of A to be reduced. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the m by n general matrix to be reduced. + On exit, the first NB rows and columns of the matrix are + overwritten; the rest of the array is unchanged. + If m >= n, elements on and below the diagonal in the first NB + columns, with the array TAUQ, represent the orthogonal + matrix Q as a product of elementary reflectors; and + elements above the diagonal in the first NB rows, with the + array TAUP, represent the orthogonal matrix P as a product + of elementary reflectors. + If m < n, elements below the diagonal in the first NB + columns, with the array TAUQ, represent the orthogonal + matrix Q as a product of elementary reflectors, and + elements on and above the diagonal in the first NB rows, + with the array TAUP, represent the orthogonal matrix P as + a product of elementary reflectors. + See Further Details. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + D (output) REAL array, dimension (NB) + The diagonal elements of the first NB rows and columns of + the reduced matrix. D(i) = A(i,i). + + E (output) REAL array, dimension (NB) + The off-diagonal elements of the first NB rows and columns of + the reduced matrix. + + TAUQ (output) REAL array dimension (NB) + The scalar factors of the elementary reflectors which + represent the orthogonal matrix Q. See Further Details. + + TAUP (output) REAL array, dimension (NB) + The scalar factors of the elementary reflectors which + represent the orthogonal matrix P. See Further Details. + + X (output) REAL array, dimension (LDX,NB) + The m-by-nb matrix X required to update the unreduced part + of A. + + LDX (input) INTEGER + The leading dimension of the array X. LDX >= M. + + Y (output) REAL array, dimension (LDY,NB) + The n-by-nb matrix Y required to update the unreduced part + of A. + + LDY (output) INTEGER + The leading dimension of the array Y. LDY >= N. + + Further Details + =============== + + The matrices Q and P are represented as products of elementary + reflectors: + + Q = H(1) H(2) . . . H(nb) and P = G(1) G(2) . . . G(nb) + + Each H(i) and G(i) has the form: + + H(i) = I - tauq * v * v' and G(i) = I - taup * u * u' + + where tauq and taup are real scalars, and v and u are real vectors. + + If m >= n, v(1:i-1) = 0, v(i) = 1, and v(i:m) is stored on exit in + A(i:m,i); u(1:i) = 0, u(i+1) = 1, and u(i+1:n) is stored on exit in + A(i,i+1:n); tauq is stored in TAUQ(i) and taup in TAUP(i). + + If m < n, v(1:i) = 0, v(i+1) = 1, and v(i+1:m) is stored on exit in + A(i+2:m,i); u(1:i-1) = 0, u(i) = 1, and u(i:n) is stored on exit in + A(i,i+1:n); tauq is stored in TAUQ(i) and taup in TAUP(i). + + The elements of the vectors v and u together form the m-by-nb matrix + V and the nb-by-n matrix U' which are needed, with X and Y, to apply + the transformation to the unreduced part of the matrix, using a block + update of the form: A := A - V*Y' - X*U'. + + The contents of A on exit are illustrated by the following examples + with nb = 2: + + m = 6 and n = 5 (m > n): m = 5 and n = 6 (m < n): + + ( 1 1 u1 u1 u1 ) ( 1 u1 u1 u1 u1 u1 ) + ( v1 1 1 u2 u2 ) ( 1 1 u2 u2 u2 u2 ) + ( v1 v2 a a a ) ( v1 1 a a a a ) + ( v1 v2 a a a ) ( v1 v2 a a a a ) + ( v1 v2 a a a ) ( v1 v2 a a a a ) + ( v1 v2 a a a ) + + where a denotes an element of the original matrix which is unchanged, + vi denotes an element of the vector defining H(i), and ui an element + of the vector defining G(i). + + ===================================================================== + + + Quick return if possible +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --d__; + --e; + --tauq; + --taup; + x_dim1 = *ldx; + x_offset = 1 + x_dim1; + x -= x_offset; + y_dim1 = *ldy; + y_offset = 1 + y_dim1; + y -= y_offset; + + /* Function Body */ + if (*m <= 0 || *n <= 0) { + return 0; + } + + if (*m >= *n) { + +/* Reduce to upper bidiagonal form */ + + i__1 = *nb; + for (i__ = 1; i__ <= i__1; ++i__) { + +/* Update A(i:m,i) */ + + i__2 = *m - i__ + 1; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &a[i__ + a_dim1], + lda, &y[i__ + y_dim1], ldy, &c_b15, &a[i__ + i__ * a_dim1] + , &c__1); + i__2 = *m - i__ + 1; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &x[i__ + x_dim1], + ldx, &a[i__ * a_dim1 + 1], &c__1, &c_b15, &a[i__ + i__ * + a_dim1], &c__1); + +/* Generate reflection Q(i) to annihilate A(i+1:m,i) */ + + i__2 = *m - i__ + 1; +/* Computing MIN */ + i__3 = i__ + 1; + slarfg_(&i__2, &a[i__ + i__ * a_dim1], &a[min(i__3,*m) + i__ * + a_dim1], &c__1, &tauq[i__]); + d__[i__] = a[i__ + i__ * a_dim1]; + if (i__ < *n) { + a[i__ + i__ * a_dim1] = 1.f; + +/* Compute Y(i+1:n,i) */ + + i__2 = *m - i__ + 1; + i__3 = *n - i__; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &a[i__ + (i__ + 1) * + a_dim1], lda, &a[i__ + i__ * a_dim1], &c__1, &c_b29, + &y[i__ + 1 + i__ * y_dim1], &c__1); + i__2 = *m - i__ + 1; + i__3 = i__ - 1; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &a[i__ + a_dim1], + lda, &a[i__ + i__ * a_dim1], &c__1, &c_b29, &y[i__ * + y_dim1 + 1], &c__1); + i__2 = *n - i__; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &y[i__ + 1 + + y_dim1], ldy, &y[i__ * y_dim1 + 1], &c__1, &c_b15, &y[ + i__ + 1 + i__ * y_dim1], &c__1); + i__2 = *m - i__ + 1; + i__3 = i__ - 1; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &x[i__ + x_dim1], + ldx, &a[i__ + i__ * a_dim1], &c__1, &c_b29, &y[i__ * + y_dim1 + 1], &c__1); + i__2 = i__ - 1; + i__3 = *n - i__; + sgemv_("Transpose", &i__2, &i__3, &c_b151, &a[(i__ + 1) * + a_dim1 + 1], lda, &y[i__ * y_dim1 + 1], &c__1, &c_b15, + &y[i__ + 1 + i__ * y_dim1], &c__1); + i__2 = *n - i__; + sscal_(&i__2, &tauq[i__], &y[i__ + 1 + i__ * y_dim1], &c__1); + +/* Update A(i,i+1:n) */ + + i__2 = *n - i__; + sgemv_("No transpose", &i__2, &i__, &c_b151, &y[i__ + 1 + + y_dim1], ldy, &a[i__ + a_dim1], lda, &c_b15, &a[i__ + + (i__ + 1) * a_dim1], lda); + i__2 = i__ - 1; + i__3 = *n - i__; + sgemv_("Transpose", &i__2, &i__3, &c_b151, &a[(i__ + 1) * + a_dim1 + 1], lda, &x[i__ + x_dim1], ldx, &c_b15, &a[ + i__ + (i__ + 1) * a_dim1], lda); + +/* Generate reflection P(i) to annihilate A(i,i+2:n) */ + + i__2 = *n - i__; +/* Computing MIN */ + i__3 = i__ + 2; + slarfg_(&i__2, &a[i__ + (i__ + 1) * a_dim1], &a[i__ + min( + i__3,*n) * a_dim1], lda, &taup[i__]); + e[i__] = a[i__ + (i__ + 1) * a_dim1]; + a[i__ + (i__ + 1) * a_dim1] = 1.f; + +/* Compute X(i+1:m,i) */ + + i__2 = *m - i__; + i__3 = *n - i__; + sgemv_("No transpose", &i__2, &i__3, &c_b15, &a[i__ + 1 + ( + i__ + 1) * a_dim1], lda, &a[i__ + (i__ + 1) * a_dim1], + lda, &c_b29, &x[i__ + 1 + i__ * x_dim1], &c__1); + i__2 = *n - i__; + sgemv_("Transpose", &i__2, &i__, &c_b15, &y[i__ + 1 + y_dim1], + ldy, &a[i__ + (i__ + 1) * a_dim1], lda, &c_b29, &x[ + i__ * x_dim1 + 1], &c__1); + i__2 = *m - i__; + sgemv_("No transpose", &i__2, &i__, &c_b151, &a[i__ + 1 + + a_dim1], lda, &x[i__ * x_dim1 + 1], &c__1, &c_b15, &x[ + i__ + 1 + i__ * x_dim1], &c__1); + i__2 = i__ - 1; + i__3 = *n - i__; + sgemv_("No transpose", &i__2, &i__3, &c_b15, &a[(i__ + 1) * + a_dim1 + 1], lda, &a[i__ + (i__ + 1) * a_dim1], lda, & + c_b29, &x[i__ * x_dim1 + 1], &c__1); + i__2 = *m - i__; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &x[i__ + 1 + + x_dim1], ldx, &x[i__ * x_dim1 + 1], &c__1, &c_b15, &x[ + i__ + 1 + i__ * x_dim1], &c__1); + i__2 = *m - i__; + sscal_(&i__2, &taup[i__], &x[i__ + 1 + i__ * x_dim1], &c__1); + } +/* L10: */ + } + } else { + +/* Reduce to lower bidiagonal form */ + + i__1 = *nb; + for (i__ = 1; i__ <= i__1; ++i__) { + +/* Update A(i,i:n) */ + + i__2 = *n - i__ + 1; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &y[i__ + y_dim1], + ldy, &a[i__ + a_dim1], lda, &c_b15, &a[i__ + i__ * a_dim1] + , lda); + i__2 = i__ - 1; + i__3 = *n - i__ + 1; + sgemv_("Transpose", &i__2, &i__3, &c_b151, &a[i__ * a_dim1 + 1], + lda, &x[i__ + x_dim1], ldx, &c_b15, &a[i__ + i__ * a_dim1] + , lda); + +/* Generate reflection P(i) to annihilate A(i,i+1:n) */ + + i__2 = *n - i__ + 1; +/* Computing MIN */ + i__3 = i__ + 1; + slarfg_(&i__2, &a[i__ + i__ * a_dim1], &a[i__ + min(i__3,*n) * + a_dim1], lda, &taup[i__]); + d__[i__] = a[i__ + i__ * a_dim1]; + if (i__ < *m) { + a[i__ + i__ * a_dim1] = 1.f; + +/* Compute X(i+1:m,i) */ + + i__2 = *m - i__; + i__3 = *n - i__ + 1; + sgemv_("No transpose", &i__2, &i__3, &c_b15, &a[i__ + 1 + i__ + * a_dim1], lda, &a[i__ + i__ * a_dim1], lda, &c_b29, & + x[i__ + 1 + i__ * x_dim1], &c__1); + i__2 = *n - i__ + 1; + i__3 = i__ - 1; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &y[i__ + y_dim1], + ldy, &a[i__ + i__ * a_dim1], lda, &c_b29, &x[i__ * + x_dim1 + 1], &c__1); + i__2 = *m - i__; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &a[i__ + 1 + + a_dim1], lda, &x[i__ * x_dim1 + 1], &c__1, &c_b15, &x[ + i__ + 1 + i__ * x_dim1], &c__1); + i__2 = i__ - 1; + i__3 = *n - i__ + 1; + sgemv_("No transpose", &i__2, &i__3, &c_b15, &a[i__ * a_dim1 + + 1], lda, &a[i__ + i__ * a_dim1], lda, &c_b29, &x[ + i__ * x_dim1 + 1], &c__1); + i__2 = *m - i__; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &x[i__ + 1 + + x_dim1], ldx, &x[i__ * x_dim1 + 1], &c__1, &c_b15, &x[ + i__ + 1 + i__ * x_dim1], &c__1); + i__2 = *m - i__; + sscal_(&i__2, &taup[i__], &x[i__ + 1 + i__ * x_dim1], &c__1); + +/* Update A(i+1:m,i) */ + + i__2 = *m - i__; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &a[i__ + 1 + + a_dim1], lda, &y[i__ + y_dim1], ldy, &c_b15, &a[i__ + + 1 + i__ * a_dim1], &c__1); + i__2 = *m - i__; + sgemv_("No transpose", &i__2, &i__, &c_b151, &x[i__ + 1 + + x_dim1], ldx, &a[i__ * a_dim1 + 1], &c__1, &c_b15, &a[ + i__ + 1 + i__ * a_dim1], &c__1); + +/* Generate reflection Q(i) to annihilate A(i+2:m,i) */ + + i__2 = *m - i__; +/* Computing MIN */ + i__3 = i__ + 2; + slarfg_(&i__2, &a[i__ + 1 + i__ * a_dim1], &a[min(i__3,*m) + + i__ * a_dim1], &c__1, &tauq[i__]); + e[i__] = a[i__ + 1 + i__ * a_dim1]; + a[i__ + 1 + i__ * a_dim1] = 1.f; + +/* Compute Y(i+1:n,i) */ + + i__2 = *m - i__; + i__3 = *n - i__; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &a[i__ + 1 + (i__ + + 1) * a_dim1], lda, &a[i__ + 1 + i__ * a_dim1], &c__1, + &c_b29, &y[i__ + 1 + i__ * y_dim1], &c__1); + i__2 = *m - i__; + i__3 = i__ - 1; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &a[i__ + 1 + a_dim1] + , lda, &a[i__ + 1 + i__ * a_dim1], &c__1, &c_b29, &y[ + i__ * y_dim1 + 1], &c__1); + i__2 = *n - i__; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &y[i__ + 1 + + y_dim1], ldy, &y[i__ * y_dim1 + 1], &c__1, &c_b15, &y[ + i__ + 1 + i__ * y_dim1], &c__1); + i__2 = *m - i__; + sgemv_("Transpose", &i__2, &i__, &c_b15, &x[i__ + 1 + x_dim1], + ldx, &a[i__ + 1 + i__ * a_dim1], &c__1, &c_b29, &y[ + i__ * y_dim1 + 1], &c__1); + i__2 = *n - i__; + sgemv_("Transpose", &i__, &i__2, &c_b151, &a[(i__ + 1) * + a_dim1 + 1], lda, &y[i__ * y_dim1 + 1], &c__1, &c_b15, + &y[i__ + 1 + i__ * y_dim1], &c__1); + i__2 = *n - i__; + sscal_(&i__2, &tauq[i__], &y[i__ + 1 + i__ * y_dim1], &c__1); + } +/* L20: */ + } + } + return 0; + +/* End of SLABRD */ + +} /* slabrd_ */ + +/* Subroutine */ int slacpy_(char *uplo, integer *m, integer *n, real *a, + integer *lda, real *b, integer *ldb) +{ + /* System generated locals */ + integer a_dim1, a_offset, b_dim1, b_offset, i__1, i__2; + + /* Local variables */ + static integer i__, j; + extern logical lsame_(char *, char *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SLACPY copies all or part of a two-dimensional matrix A to another + matrix B. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + Specifies the part of the matrix A to be copied to B. + = 'U': Upper triangular part + = 'L': Lower triangular part + Otherwise: All of the matrix A + + M (input) INTEGER + The number of rows of the matrix A. M >= 0. + + N (input) INTEGER + The number of columns of the matrix A. N >= 0. + + A (input) REAL array, dimension (LDA,N) + The m by n matrix A. If UPLO = 'U', only the upper triangle + or trapezoid is accessed; if UPLO = 'L', only the lower + triangle or trapezoid is accessed. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + B (output) REAL array, dimension (LDB,N) + On exit, B = A in the locations specified by UPLO. + + LDB (input) INTEGER + The leading dimension of the array B. LDB >= max(1,M). + + ===================================================================== +*/ + + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + b_dim1 = *ldb; + b_offset = 1 + b_dim1; + b -= b_offset; + + /* Function Body */ + if (lsame_(uplo, "U")) { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = min(j,*m); + for (i__ = 1; i__ <= i__2; ++i__) { + b[i__ + j * b_dim1] = a[i__ + j * a_dim1]; +/* L10: */ + } +/* L20: */ + } + } else if (lsame_(uplo, "L")) { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = j; i__ <= i__2; ++i__) { + b[i__ + j * b_dim1] = a[i__ + j * a_dim1]; +/* L30: */ + } +/* L40: */ + } + } else { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + b[i__ + j * b_dim1] = a[i__ + j * a_dim1]; +/* L50: */ + } +/* L60: */ + } + } + return 0; + +/* End of SLACPY */ + +} /* slacpy_ */ + +/* Subroutine */ int sladiv_(real *a, real *b, real *c__, real *d__, real *p, + real *q) +{ + static real e, f; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLADIV performs complex division in real arithmetic + + a + i*b + p + i*q = --------- + c + i*d + + The algorithm is due to Robert L. Smith and can be found + in D. Knuth, The art of Computer Programming, Vol.2, p.195 + + Arguments + ========= + + A (input) REAL + B (input) REAL + C (input) REAL + D (input) REAL + The scalars a, b, c, and d in the above expression. + + P (output) REAL + Q (output) REAL + The scalars p and q in the above expression. + + ===================================================================== +*/ + + + if (dabs(*d__) < dabs(*c__)) { + e = *d__ / *c__; + f = *c__ + *d__ * e; + *p = (*a + *b * e) / f; + *q = (*b - *a * e) / f; + } else { + e = *c__ / *d__; + f = *d__ + *c__ * e; + *p = (*b + *a * e) / f; + *q = (-(*a) + *b * e) / f; + } + + return 0; + +/* End of SLADIV */ + +} /* sladiv_ */ + +/* Subroutine */ int slae2_(real *a, real *b, real *c__, real *rt1, real *rt2) +{ + /* System generated locals */ + real r__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real ab, df, tb, sm, rt, adf, acmn, acmx; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLAE2 computes the eigenvalues of a 2-by-2 symmetric matrix + [ A B ] + [ B C ]. + On return, RT1 is the eigenvalue of larger absolute value, and RT2 + is the eigenvalue of smaller absolute value. + + Arguments + ========= + + A (input) REAL + The (1,1) element of the 2-by-2 matrix. + + B (input) REAL + The (1,2) and (2,1) elements of the 2-by-2 matrix. + + C (input) REAL + The (2,2) element of the 2-by-2 matrix. + + RT1 (output) REAL + The eigenvalue of larger absolute value. + + RT2 (output) REAL + The eigenvalue of smaller absolute value. + + Further Details + =============== + + RT1 is accurate to a few ulps barring over/underflow. + + RT2 may be inaccurate if there is massive cancellation in the + determinant A*C-B*B; higher precision or correctly rounded or + correctly truncated arithmetic would be needed to compute RT2 + accurately in all cases. + + Overflow is possible only if RT1 is within a factor of 5 of overflow. + Underflow is harmless if the input data is 0 or exceeds + underflow_threshold / macheps. + + ===================================================================== + + + Compute the eigenvalues +*/ + + sm = *a + *c__; + df = *a - *c__; + adf = dabs(df); + tb = *b + *b; + ab = dabs(tb); + if (dabs(*a) > dabs(*c__)) { + acmx = *a; + acmn = *c__; + } else { + acmx = *c__; + acmn = *a; + } + if (adf > ab) { +/* Computing 2nd power */ + r__1 = ab / adf; + rt = adf * sqrt(r__1 * r__1 + 1.f); + } else if (adf < ab) { +/* Computing 2nd power */ + r__1 = adf / ab; + rt = ab * sqrt(r__1 * r__1 + 1.f); + } else { + +/* Includes case AB=ADF=0 */ + + rt = ab * sqrt(2.f); + } + if (sm < 0.f) { + *rt1 = (sm - rt) * .5f; + +/* + Order of execution important. + To get fully accurate smaller eigenvalue, + next line needs to be executed in higher precision. +*/ + + *rt2 = acmx / *rt1 * acmn - *b / *rt1 * *b; + } else if (sm > 0.f) { + *rt1 = (sm + rt) * .5f; + +/* + Order of execution important. + To get fully accurate smaller eigenvalue, + next line needs to be executed in higher precision. +*/ + + *rt2 = acmx / *rt1 * acmn - *b / *rt1 * *b; + } else { + +/* Includes case RT1 = RT2 = 0 */ + + *rt1 = rt * .5f; + *rt2 = rt * -.5f; + } + return 0; + +/* End of SLAE2 */ + +} /* slae2_ */ + +/* Subroutine */ int slaed0_(integer *icompq, integer *qsiz, integer *n, real + *d__, real *e, real *q, integer *ldq, real *qstore, integer *ldqs, + real *work, integer *iwork, integer *info) +{ + /* System generated locals */ + integer q_dim1, q_offset, qstore_dim1, qstore_offset, i__1, i__2; + real r__1; + + /* Builtin functions */ + double log(doublereal); + integer pow_ii(integer *, integer *); + + /* Local variables */ + static integer i__, j, k, iq, lgn, msd2, smm1, spm1, spm2; + static real temp; + static integer curr; + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *); + static integer iperm, indxq, iwrem; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *); + static integer iqptr, tlvls; + extern /* Subroutine */ int slaed1_(integer *, real *, real *, integer *, + integer *, real *, integer *, real *, integer *, integer *), + slaed7_(integer *, integer *, integer *, integer *, integer *, + integer *, real *, real *, integer *, integer *, real *, integer * + , real *, integer *, integer *, integer *, integer *, integer *, + real *, real *, integer *, integer *); + static integer igivcl; + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + static integer igivnm, submat; + extern /* Subroutine */ int slacpy_(char *, integer *, integer *, real *, + integer *, real *, integer *); + static integer curprb, subpbs, igivpt, curlvl, matsiz, iprmpt, smlsiz; + extern /* Subroutine */ int ssteqr_(char *, integer *, real *, real *, + real *, integer *, real *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SLAED0 computes all eigenvalues and corresponding eigenvectors of a + symmetric tridiagonal matrix using the divide and conquer method. + + Arguments + ========= + + ICOMPQ (input) INTEGER + = 0: Compute eigenvalues only. + = 1: Compute eigenvectors of original dense symmetric matrix + also. On entry, Q contains the orthogonal matrix used + to reduce the original matrix to tridiagonal form. + = 2: Compute eigenvalues and eigenvectors of tridiagonal + matrix. + + QSIZ (input) INTEGER + The dimension of the orthogonal matrix used to reduce + the full matrix to tridiagonal form. QSIZ >= N if ICOMPQ = 1. + + N (input) INTEGER + The dimension of the symmetric tridiagonal matrix. N >= 0. + + D (input/output) REAL array, dimension (N) + On entry, the main diagonal of the tridiagonal matrix. + On exit, its eigenvalues. + + E (input) REAL array, dimension (N-1) + The off-diagonal elements of the tridiagonal matrix. + On exit, E has been destroyed. + + Q (input/output) REAL array, dimension (LDQ, N) + On entry, Q must contain an N-by-N orthogonal matrix. + If ICOMPQ = 0 Q is not referenced. + If ICOMPQ = 1 On entry, Q is a subset of the columns of the + orthogonal matrix used to reduce the full + matrix to tridiagonal form corresponding to + the subset of the full matrix which is being + decomposed at this time. + If ICOMPQ = 2 On entry, Q will be the identity matrix. + On exit, Q contains the eigenvectors of the + tridiagonal matrix. + + LDQ (input) INTEGER + The leading dimension of the array Q. If eigenvectors are + desired, then LDQ >= max(1,N). In any case, LDQ >= 1. + + QSTORE (workspace) REAL array, dimension (LDQS, N) + Referenced only when ICOMPQ = 1. Used to store parts of + the eigenvector matrix when the updating matrix multiplies + take place. + + LDQS (input) INTEGER + The leading dimension of the array QSTORE. If ICOMPQ = 1, + then LDQS >= max(1,N). In any case, LDQS >= 1. + + WORK (workspace) REAL array, + If ICOMPQ = 0 or 1, the dimension of WORK must be at least + 1 + 3*N + 2*N*lg N + 2*N**2 + ( lg( N ) = smallest integer k + such that 2^k >= N ) + If ICOMPQ = 2, the dimension of WORK must be at least + 4*N + N**2. + + IWORK (workspace) INTEGER array, + If ICOMPQ = 0 or 1, the dimension of IWORK must be at least + 6 + 6*N + 5*N*lg N. + ( lg( N ) = smallest integer k + such that 2^k >= N ) + If ICOMPQ = 2, the dimension of IWORK must be at least + 3 + 5*N. + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: The algorithm failed to compute an eigenvalue while + working on the submatrix lying in rows and columns + INFO/(N+1) through mod(INFO,N+1). + + Further Details + =============== + + Based on contributions by + Jeff Rutter, Computer Science Division, University of California + at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --e; + q_dim1 = *ldq; + q_offset = 1 + q_dim1; + q -= q_offset; + qstore_dim1 = *ldqs; + qstore_offset = 1 + qstore_dim1; + qstore -= qstore_offset; + --work; + --iwork; + + /* Function Body */ + *info = 0; + + if (*icompq < 0 || *icompq > 2) { + *info = -1; + } else if (*icompq == 1 && *qsiz < max(0,*n)) { + *info = -2; + } else if (*n < 0) { + *info = -3; + } else if (*ldq < max(1,*n)) { + *info = -7; + } else if (*ldqs < max(1,*n)) { + *info = -9; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLAED0", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + + smlsiz = ilaenv_(&c__9, "SLAED0", " ", &c__0, &c__0, &c__0, &c__0, ( + ftnlen)6, (ftnlen)1); + +/* + Determine the size and placement of the submatrices, and save in + the leading elements of IWORK. +*/ + + iwork[1] = *n; + subpbs = 1; + tlvls = 0; +L10: + if (iwork[subpbs] > smlsiz) { + for (j = subpbs; j >= 1; --j) { + iwork[j * 2] = (iwork[j] + 1) / 2; + iwork[(j << 1) - 1] = iwork[j] / 2; +/* L20: */ + } + ++tlvls; + subpbs <<= 1; + goto L10; + } + i__1 = subpbs; + for (j = 2; j <= i__1; ++j) { + iwork[j] += iwork[j - 1]; +/* L30: */ + } + +/* + Divide the matrix into SUBPBS submatrices of size at most SMLSIZ+1 + using rank-1 modifications (cuts). +*/ + + spm1 = subpbs - 1; + i__1 = spm1; + for (i__ = 1; i__ <= i__1; ++i__) { + submat = iwork[i__] + 1; + smm1 = submat - 1; + d__[smm1] -= (r__1 = e[smm1], dabs(r__1)); + d__[submat] -= (r__1 = e[smm1], dabs(r__1)); +/* L40: */ + } + + indxq = (*n << 2) + 3; + if (*icompq != 2) { + +/* + Set up workspaces for eigenvalues only/accumulate new vectors + routine +*/ + + temp = log((real) (*n)) / log(2.f); + lgn = (integer) temp; + if (pow_ii(&c__2, &lgn) < *n) { + ++lgn; + } + if (pow_ii(&c__2, &lgn) < *n) { + ++lgn; + } + iprmpt = indxq + *n + 1; + iperm = iprmpt + *n * lgn; + iqptr = iperm + *n * lgn; + igivpt = iqptr + *n + 2; + igivcl = igivpt + *n * lgn; + + igivnm = 1; + iq = igivnm + (*n << 1) * lgn; +/* Computing 2nd power */ + i__1 = *n; + iwrem = iq + i__1 * i__1 + 1; + +/* Initialize pointers */ + + i__1 = subpbs; + for (i__ = 0; i__ <= i__1; ++i__) { + iwork[iprmpt + i__] = 1; + iwork[igivpt + i__] = 1; +/* L50: */ + } + iwork[iqptr] = 1; + } + +/* + Solve each submatrix eigenproblem at the bottom of the divide and + conquer tree. +*/ + + curr = 0; + i__1 = spm1; + for (i__ = 0; i__ <= i__1; ++i__) { + if (i__ == 0) { + submat = 1; + matsiz = iwork[1]; + } else { + submat = iwork[i__] + 1; + matsiz = iwork[i__ + 1] - iwork[i__]; + } + if (*icompq == 2) { + ssteqr_("I", &matsiz, &d__[submat], &e[submat], &q[submat + + submat * q_dim1], ldq, &work[1], info); + if (*info != 0) { + goto L130; + } + } else { + ssteqr_("I", &matsiz, &d__[submat], &e[submat], &work[iq - 1 + + iwork[iqptr + curr]], &matsiz, &work[1], info); + if (*info != 0) { + goto L130; + } + if (*icompq == 1) { + sgemm_("N", "N", qsiz, &matsiz, &matsiz, &c_b15, &q[submat * + q_dim1 + 1], ldq, &work[iq - 1 + iwork[iqptr + curr]], + &matsiz, &c_b29, &qstore[submat * qstore_dim1 + 1], + ldqs); + } +/* Computing 2nd power */ + i__2 = matsiz; + iwork[iqptr + curr + 1] = iwork[iqptr + curr] + i__2 * i__2; + ++curr; + } + k = 1; + i__2 = iwork[i__ + 1]; + for (j = submat; j <= i__2; ++j) { + iwork[indxq + j] = k; + ++k; +/* L60: */ + } +/* L70: */ + } + +/* + Successively merge eigensystems of adjacent submatrices + into eigensystem for the corresponding larger matrix. + + while ( SUBPBS > 1 ) +*/ + + curlvl = 1; +L80: + if (subpbs > 1) { + spm2 = subpbs - 2; + i__1 = spm2; + for (i__ = 0; i__ <= i__1; i__ += 2) { + if (i__ == 0) { + submat = 1; + matsiz = iwork[2]; + msd2 = iwork[1]; + curprb = 0; + } else { + submat = iwork[i__] + 1; + matsiz = iwork[i__ + 2] - iwork[i__]; + msd2 = matsiz / 2; + ++curprb; + } + +/* + Merge lower order eigensystems (of size MSD2 and MATSIZ - MSD2) + into an eigensystem of size MATSIZ. + SLAED1 is used only for the full eigensystem of a tridiagonal + matrix. + SLAED7 handles the cases in which eigenvalues only or eigenvalues + and eigenvectors of a full symmetric matrix (which was reduced to + tridiagonal form) are desired. +*/ + + if (*icompq == 2) { + slaed1_(&matsiz, &d__[submat], &q[submat + submat * q_dim1], + ldq, &iwork[indxq + submat], &e[submat + msd2 - 1], & + msd2, &work[1], &iwork[subpbs + 1], info); + } else { + slaed7_(icompq, &matsiz, qsiz, &tlvls, &curlvl, &curprb, &d__[ + submat], &qstore[submat * qstore_dim1 + 1], ldqs, & + iwork[indxq + submat], &e[submat + msd2 - 1], &msd2, & + work[iq], &iwork[iqptr], &iwork[iprmpt], &iwork[iperm] + , &iwork[igivpt], &iwork[igivcl], &work[igivnm], & + work[iwrem], &iwork[subpbs + 1], info); + } + if (*info != 0) { + goto L130; + } + iwork[i__ / 2 + 1] = iwork[i__ + 2]; +/* L90: */ + } + subpbs /= 2; + ++curlvl; + goto L80; + } + +/* + end while + + Re-merge the eigenvalues/vectors which were deflated at the final + merge step. +*/ + + if (*icompq == 1) { + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + j = iwork[indxq + i__]; + work[i__] = d__[j]; + scopy_(qsiz, &qstore[j * qstore_dim1 + 1], &c__1, &q[i__ * q_dim1 + + 1], &c__1); +/* L100: */ + } + scopy_(n, &work[1], &c__1, &d__[1], &c__1); + } else if (*icompq == 2) { + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + j = iwork[indxq + i__]; + work[i__] = d__[j]; + scopy_(n, &q[j * q_dim1 + 1], &c__1, &work[*n * i__ + 1], &c__1); +/* L110: */ + } + scopy_(n, &work[1], &c__1, &d__[1], &c__1); + slacpy_("A", n, n, &work[*n + 1], n, &q[q_offset], ldq); + } else { + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + j = iwork[indxq + i__]; + work[i__] = d__[j]; +/* L120: */ + } + scopy_(n, &work[1], &c__1, &d__[1], &c__1); + } + goto L140; + +L130: + *info = submat * (*n + 1) + submat + matsiz - 1; + +L140: + return 0; + +/* End of SLAED0 */ + +} /* slaed0_ */ + +/* Subroutine */ int slaed1_(integer *n, real *d__, real *q, integer *ldq, + integer *indxq, real *rho, integer *cutpnt, real *work, integer * + iwork, integer *info) +{ + /* System generated locals */ + integer q_dim1, q_offset, i__1, i__2; + + /* Local variables */ + static integer i__, k, n1, n2, is, iw, iz, iq2, cpp1, indx, indxc, indxp; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *), slaed2_(integer *, integer *, integer *, real *, real + *, integer *, integer *, real *, real *, real *, real *, real *, + integer *, integer *, integer *, integer *, integer *), slaed3_( + integer *, integer *, integer *, real *, real *, integer *, real * + , real *, real *, integer *, integer *, real *, real *, integer *) + ; + static integer idlmda; + extern /* Subroutine */ int xerbla_(char *, integer *), slamrg_( + integer *, integer *, real *, integer *, integer *, integer *); + static integer coltyp; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SLAED1 computes the updated eigensystem of a diagonal + matrix after modification by a rank-one symmetric matrix. This + routine is used only for the eigenproblem which requires all + eigenvalues and eigenvectors of a tridiagonal matrix. SLAED7 handles + the case in which eigenvalues only or eigenvalues and eigenvectors + of a full symmetric matrix (which was reduced to tridiagonal form) + are desired. + + T = Q(in) ( D(in) + RHO * Z*Z' ) Q'(in) = Q(out) * D(out) * Q'(out) + + where Z = Q'u, u is a vector of length N with ones in the + CUTPNT and CUTPNT + 1 th elements and zeros elsewhere. + + The eigenvectors of the original matrix are stored in Q, and the + eigenvalues are in D. The algorithm consists of three stages: + + The first stage consists of deflating the size of the problem + when there are multiple eigenvalues or if there is a zero in + the Z vector. For each such occurence the dimension of the + secular equation problem is reduced by one. This stage is + performed by the routine SLAED2. + + The second stage consists of calculating the updated + eigenvalues. This is done by finding the roots of the secular + equation via the routine SLAED4 (as called by SLAED3). + This routine also calculates the eigenvectors of the current + problem. + + The final stage consists of computing the updated eigenvectors + directly using the updated eigenvalues. The eigenvectors for + the current problem are multiplied with the eigenvectors from + the overall problem. + + Arguments + ========= + + N (input) INTEGER + The dimension of the symmetric tridiagonal matrix. N >= 0. + + D (input/output) REAL array, dimension (N) + On entry, the eigenvalues of the rank-1-perturbed matrix. + On exit, the eigenvalues of the repaired matrix. + + Q (input/output) REAL array, dimension (LDQ,N) + On entry, the eigenvectors of the rank-1-perturbed matrix. + On exit, the eigenvectors of the repaired tridiagonal matrix. + + LDQ (input) INTEGER + The leading dimension of the array Q. LDQ >= max(1,N). + + INDXQ (input/output) INTEGER array, dimension (N) + On entry, the permutation which separately sorts the two + subproblems in D into ascending order. + On exit, the permutation which will reintegrate the + subproblems back into sorted order, + i.e. D( INDXQ( I = 1, N ) ) will be in ascending order. + + RHO (input) REAL + The subdiagonal entry used to create the rank-1 modification. + + CUTPNT (input) INTEGER + The location of the last eigenvalue in the leading sub-matrix. + min(1,N) <= CUTPNT <= N/2. + + WORK (workspace) REAL array, dimension (4*N + N**2) + + IWORK (workspace) INTEGER array, dimension (4*N) + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: if INFO = 1, an eigenvalue did not converge + + Further Details + =============== + + Based on contributions by + Jeff Rutter, Computer Science Division, University of California + at Berkeley, USA + Modified by Francoise Tisseur, University of Tennessee. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + q_dim1 = *ldq; + q_offset = 1 + q_dim1; + q -= q_offset; + --indxq; + --work; + --iwork; + + /* Function Body */ + *info = 0; + + if (*n < 0) { + *info = -1; + } else if (*ldq < max(1,*n)) { + *info = -4; + } else /* if(complicated condition) */ { +/* Computing MIN */ + i__1 = 1, i__2 = *n / 2; + if (min(i__1,i__2) > *cutpnt || *n / 2 < *cutpnt) { + *info = -7; + } + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLAED1", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + +/* + The following values are integer pointers which indicate + the portion of the workspace + used by a particular array in SLAED2 and SLAED3. +*/ + + iz = 1; + idlmda = iz + *n; + iw = idlmda + *n; + iq2 = iw + *n; + + indx = 1; + indxc = indx + *n; + coltyp = indxc + *n; + indxp = coltyp + *n; + + +/* + Form the z-vector which consists of the last row of Q_1 and the + first row of Q_2. +*/ + + scopy_(cutpnt, &q[*cutpnt + q_dim1], ldq, &work[iz], &c__1); + cpp1 = *cutpnt + 1; + i__1 = *n - *cutpnt; + scopy_(&i__1, &q[cpp1 + cpp1 * q_dim1], ldq, &work[iz + *cutpnt], &c__1); + +/* Deflate eigenvalues. */ + + slaed2_(&k, n, cutpnt, &d__[1], &q[q_offset], ldq, &indxq[1], rho, &work[ + iz], &work[idlmda], &work[iw], &work[iq2], &iwork[indx], &iwork[ + indxc], &iwork[indxp], &iwork[coltyp], info); + + if (*info != 0) { + goto L20; + } + +/* Solve Secular Equation. */ + + if (k != 0) { + is = (iwork[coltyp] + iwork[coltyp + 1]) * *cutpnt + (iwork[coltyp + + 1] + iwork[coltyp + 2]) * (*n - *cutpnt) + iq2; + slaed3_(&k, n, cutpnt, &d__[1], &q[q_offset], ldq, rho, &work[idlmda], + &work[iq2], &iwork[indxc], &iwork[coltyp], &work[iw], &work[ + is], info); + if (*info != 0) { + goto L20; + } + +/* Prepare the INDXQ sorting permutation. */ + + n1 = k; + n2 = *n - k; + slamrg_(&n1, &n2, &d__[1], &c__1, &c_n1, &indxq[1]); + } else { + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + indxq[i__] = i__; +/* L10: */ + } + } + +L20: + return 0; + +/* End of SLAED1 */ + +} /* slaed1_ */ + +/* Subroutine */ int slaed2_(integer *k, integer *n, integer *n1, real *d__, + real *q, integer *ldq, integer *indxq, real *rho, real *z__, real * + dlamda, real *w, real *q2, integer *indx, integer *indxc, integer * + indxp, integer *coltyp, integer *info) +{ + /* System generated locals */ + integer q_dim1, q_offset, i__1, i__2; + real r__1, r__2, r__3, r__4; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real c__; + static integer i__, j; + static real s, t; + static integer k2, n2, ct, nj, pj, js, iq1, iq2, n1p1; + static real eps, tau, tol; + static integer psm[4], imax, jmax, ctot[4]; + extern /* Subroutine */ int srot_(integer *, real *, integer *, real *, + integer *, real *, real *), sscal_(integer *, real *, real *, + integer *), scopy_(integer *, real *, integer *, real *, integer * + ); + extern doublereal slapy2_(real *, real *), slamch_(char *); + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer isamax_(integer *, real *, integer *); + extern /* Subroutine */ int slamrg_(integer *, integer *, real *, integer + *, integer *, integer *), slacpy_(char *, integer *, integer *, + real *, integer *, real *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1999 + + + Purpose + ======= + + SLAED2 merges the two sets of eigenvalues together into a single + sorted set. Then it tries to deflate the size of the problem. + There are two ways in which deflation can occur: when two or more + eigenvalues are close together or if there is a tiny entry in the + Z vector. For each such occurrence the order of the related secular + equation problem is reduced by one. + + Arguments + ========= + + K (output) INTEGER + The number of non-deflated eigenvalues, and the order of the + related secular equation. 0 <= K <=N. + + N (input) INTEGER + The dimension of the symmetric tridiagonal matrix. N >= 0. + + N1 (input) INTEGER + The location of the last eigenvalue in the leading sub-matrix. + min(1,N) <= N1 <= N/2. + + D (input/output) REAL array, dimension (N) + On entry, D contains the eigenvalues of the two submatrices to + be combined. + On exit, D contains the trailing (N-K) updated eigenvalues + (those which were deflated) sorted into increasing order. + + Q (input/output) REAL array, dimension (LDQ, N) + On entry, Q contains the eigenvectors of two submatrices in + the two square blocks with corners at (1,1), (N1,N1) + and (N1+1, N1+1), (N,N). + On exit, Q contains the trailing (N-K) updated eigenvectors + (those which were deflated) in its last N-K columns. + + LDQ (input) INTEGER + The leading dimension of the array Q. LDQ >= max(1,N). + + INDXQ (input/output) INTEGER array, dimension (N) + The permutation which separately sorts the two sub-problems + in D into ascending order. Note that elements in the second + half of this permutation must first have N1 added to their + values. Destroyed on exit. + + RHO (input/output) REAL + On entry, the off-diagonal element associated with the rank-1 + cut which originally split the two submatrices which are now + being recombined. + On exit, RHO has been modified to the value required by + SLAED3. + + Z (input) REAL array, dimension (N) + On entry, Z contains the updating vector (the last + row of the first sub-eigenvector matrix and the first row of + the second sub-eigenvector matrix). + On exit, the contents of Z have been destroyed by the updating + process. + + DLAMDA (output) REAL array, dimension (N) + A copy of the first K eigenvalues which will be used by + SLAED3 to form the secular equation. + + W (output) REAL array, dimension (N) + The first k values of the final deflation-altered z-vector + which will be passed to SLAED3. + + Q2 (output) REAL array, dimension (N1**2+(N-N1)**2) + A copy of the first K eigenvectors which will be used by + SLAED3 in a matrix multiply (SGEMM) to solve for the new + eigenvectors. + + INDX (workspace) INTEGER array, dimension (N) + The permutation used to sort the contents of DLAMDA into + ascending order. + + INDXC (output) INTEGER array, dimension (N) + The permutation used to arrange the columns of the deflated + Q matrix into three groups: the first group contains non-zero + elements only at and above N1, the second contains + non-zero elements only below N1, and the third is dense. + + INDXP (workspace) INTEGER array, dimension (N) + The permutation used to place deflated values of D at the end + of the array. INDXP(1:K) points to the nondeflated D-values + and INDXP(K+1:N) points to the deflated eigenvalues. + + COLTYP (workspace/output) INTEGER array, dimension (N) + During execution, a label which will indicate which of the + following types a column in the Q2 matrix is: + 1 : non-zero in the upper half only; + 2 : dense; + 3 : non-zero in the lower half only; + 4 : deflated. + On exit, COLTYP(i) is the number of columns of type i, + for i=1 to 4 only. + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + + Further Details + =============== + + Based on contributions by + Jeff Rutter, Computer Science Division, University of California + at Berkeley, USA + Modified by Francoise Tisseur, University of Tennessee. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + q_dim1 = *ldq; + q_offset = 1 + q_dim1; + q -= q_offset; + --indxq; + --z__; + --dlamda; + --w; + --q2; + --indx; + --indxc; + --indxp; + --coltyp; + + /* Function Body */ + *info = 0; + + if (*n < 0) { + *info = -2; + } else if (*ldq < max(1,*n)) { + *info = -6; + } else /* if(complicated condition) */ { +/* Computing MIN */ + i__1 = 1, i__2 = *n / 2; + if (min(i__1,i__2) > *n1 || *n / 2 < *n1) { + *info = -3; + } + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLAED2", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + + n2 = *n - *n1; + n1p1 = *n1 + 1; + + if (*rho < 0.f) { + sscal_(&n2, &c_b151, &z__[n1p1], &c__1); + } + +/* + Normalize z so that norm(z) = 1. Since z is the concatenation of + two normalized vectors, norm2(z) = sqrt(2). +*/ + + t = 1.f / sqrt(2.f); + sscal_(n, &t, &z__[1], &c__1); + +/* RHO = ABS( norm(z)**2 * RHO ) */ + + *rho = (r__1 = *rho * 2.f, dabs(r__1)); + +/* Sort the eigenvalues into increasing order */ + + i__1 = *n; + for (i__ = n1p1; i__ <= i__1; ++i__) { + indxq[i__] += *n1; +/* L10: */ + } + +/* re-integrate the deflated parts from the last pass */ + + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + dlamda[i__] = d__[indxq[i__]]; +/* L20: */ + } + slamrg_(n1, &n2, &dlamda[1], &c__1, &c__1, &indxc[1]); + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + indx[i__] = indxq[indxc[i__]]; +/* L30: */ + } + +/* Calculate the allowable deflation tolerance */ + + imax = isamax_(n, &z__[1], &c__1); + jmax = isamax_(n, &d__[1], &c__1); + eps = slamch_("Epsilon"); +/* Computing MAX */ + r__3 = (r__1 = d__[jmax], dabs(r__1)), r__4 = (r__2 = z__[imax], dabs( + r__2)); + tol = eps * 8.f * dmax(r__3,r__4); + +/* + If the rank-1 modifier is small enough, no more needs to be done + except to reorganize Q so that its columns correspond with the + elements in D. +*/ + + if (*rho * (r__1 = z__[imax], dabs(r__1)) <= tol) { + *k = 0; + iq2 = 1; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__ = indx[j]; + scopy_(n, &q[i__ * q_dim1 + 1], &c__1, &q2[iq2], &c__1); + dlamda[j] = d__[i__]; + iq2 += *n; +/* L40: */ + } + slacpy_("A", n, n, &q2[1], n, &q[q_offset], ldq); + scopy_(n, &dlamda[1], &c__1, &d__[1], &c__1); + goto L190; + } + +/* + If there are multiple eigenvalues then the problem deflates. Here + the number of equal eigenvalues are found. As each equal + eigenvalue is found, an elementary reflector is computed to rotate + the corresponding eigensubspace so that the corresponding + components of Z are zero in this new basis. +*/ + + i__1 = *n1; + for (i__ = 1; i__ <= i__1; ++i__) { + coltyp[i__] = 1; +/* L50: */ + } + i__1 = *n; + for (i__ = n1p1; i__ <= i__1; ++i__) { + coltyp[i__] = 3; +/* L60: */ + } + + + *k = 0; + k2 = *n + 1; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + nj = indx[j]; + if (*rho * (r__1 = z__[nj], dabs(r__1)) <= tol) { + +/* Deflate due to small z component. */ + + --k2; + coltyp[nj] = 4; + indxp[k2] = nj; + if (j == *n) { + goto L100; + } + } else { + pj = nj; + goto L80; + } +/* L70: */ + } +L80: + ++j; + nj = indx[j]; + if (j > *n) { + goto L100; + } + if (*rho * (r__1 = z__[nj], dabs(r__1)) <= tol) { + +/* Deflate due to small z component. */ + + --k2; + coltyp[nj] = 4; + indxp[k2] = nj; + } else { + +/* Check if eigenvalues are close enough to allow deflation. */ + + s = z__[pj]; + c__ = z__[nj]; + +/* + Find sqrt(a**2+b**2) without overflow or + destructive underflow. +*/ + + tau = slapy2_(&c__, &s); + t = d__[nj] - d__[pj]; + c__ /= tau; + s = -s / tau; + if ((r__1 = t * c__ * s, dabs(r__1)) <= tol) { + +/* Deflation is possible. */ + + z__[nj] = tau; + z__[pj] = 0.f; + if (coltyp[nj] != coltyp[pj]) { + coltyp[nj] = 2; + } + coltyp[pj] = 4; + srot_(n, &q[pj * q_dim1 + 1], &c__1, &q[nj * q_dim1 + 1], &c__1, & + c__, &s); +/* Computing 2nd power */ + r__1 = c__; +/* Computing 2nd power */ + r__2 = s; + t = d__[pj] * (r__1 * r__1) + d__[nj] * (r__2 * r__2); +/* Computing 2nd power */ + r__1 = s; +/* Computing 2nd power */ + r__2 = c__; + d__[nj] = d__[pj] * (r__1 * r__1) + d__[nj] * (r__2 * r__2); + d__[pj] = t; + --k2; + i__ = 1; +L90: + if (k2 + i__ <= *n) { + if (d__[pj] < d__[indxp[k2 + i__]]) { + indxp[k2 + i__ - 1] = indxp[k2 + i__]; + indxp[k2 + i__] = pj; + ++i__; + goto L90; + } else { + indxp[k2 + i__ - 1] = pj; + } + } else { + indxp[k2 + i__ - 1] = pj; + } + pj = nj; + } else { + ++(*k); + dlamda[*k] = d__[pj]; + w[*k] = z__[pj]; + indxp[*k] = pj; + pj = nj; + } + } + goto L80; +L100: + +/* Record the last eigenvalue. */ + + ++(*k); + dlamda[*k] = d__[pj]; + w[*k] = z__[pj]; + indxp[*k] = pj; + +/* + Count up the total number of the various types of columns, then + form a permutation which positions the four column types into + four uniform groups (although one or more of these groups may be + empty). +*/ + + for (j = 1; j <= 4; ++j) { + ctot[j - 1] = 0; +/* L110: */ + } + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + ct = coltyp[j]; + ++ctot[ct - 1]; +/* L120: */ + } + +/* PSM(*) = Position in SubMatrix (of types 1 through 4) */ + + psm[0] = 1; + psm[1] = ctot[0] + 1; + psm[2] = psm[1] + ctot[1]; + psm[3] = psm[2] + ctot[2]; + *k = *n - ctot[3]; + +/* + Fill out the INDXC array so that the permutation which it induces + will place all type-1 columns first, all type-2 columns next, + then all type-3's, and finally all type-4's. +*/ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + js = indxp[j]; + ct = coltyp[js]; + indx[psm[ct - 1]] = js; + indxc[psm[ct - 1]] = j; + ++psm[ct - 1]; +/* L130: */ + } + +/* + Sort the eigenvalues and corresponding eigenvectors into DLAMDA + and Q2 respectively. The eigenvalues/vectors which were not + deflated go into the first K slots of DLAMDA and Q2 respectively, + while those which were deflated go into the last N - K slots. +*/ + + i__ = 1; + iq1 = 1; + iq2 = (ctot[0] + ctot[1]) * *n1 + 1; + i__1 = ctot[0]; + for (j = 1; j <= i__1; ++j) { + js = indx[i__]; + scopy_(n1, &q[js * q_dim1 + 1], &c__1, &q2[iq1], &c__1); + z__[i__] = d__[js]; + ++i__; + iq1 += *n1; +/* L140: */ + } + + i__1 = ctot[1]; + for (j = 1; j <= i__1; ++j) { + js = indx[i__]; + scopy_(n1, &q[js * q_dim1 + 1], &c__1, &q2[iq1], &c__1); + scopy_(&n2, &q[*n1 + 1 + js * q_dim1], &c__1, &q2[iq2], &c__1); + z__[i__] = d__[js]; + ++i__; + iq1 += *n1; + iq2 += n2; +/* L150: */ + } + + i__1 = ctot[2]; + for (j = 1; j <= i__1; ++j) { + js = indx[i__]; + scopy_(&n2, &q[*n1 + 1 + js * q_dim1], &c__1, &q2[iq2], &c__1); + z__[i__] = d__[js]; + ++i__; + iq2 += n2; +/* L160: */ + } + + iq1 = iq2; + i__1 = ctot[3]; + for (j = 1; j <= i__1; ++j) { + js = indx[i__]; + scopy_(n, &q[js * q_dim1 + 1], &c__1, &q2[iq2], &c__1); + iq2 += *n; + z__[i__] = d__[js]; + ++i__; +/* L170: */ + } + +/* + The deflated eigenvalues and their corresponding vectors go back + into the last N - K slots of D and Q respectively. +*/ + + slacpy_("A", n, &ctot[3], &q2[iq1], n, &q[(*k + 1) * q_dim1 + 1], ldq); + i__1 = *n - *k; + scopy_(&i__1, &z__[*k + 1], &c__1, &d__[*k + 1], &c__1); + +/* Copy CTOT into COLTYP for referencing in SLAED3. */ + + for (j = 1; j <= 4; ++j) { + coltyp[j] = ctot[j - 1]; +/* L180: */ + } + +L190: + return 0; + +/* End of SLAED2 */ + +} /* slaed2_ */ + +/* Subroutine */ int slaed3_(integer *k, integer *n, integer *n1, real *d__, + real *q, integer *ldq, real *rho, real *dlamda, real *q2, integer * + indx, integer *ctot, real *w, real *s, integer *info) +{ + /* System generated locals */ + integer q_dim1, q_offset, i__1, i__2; + real r__1; + + /* Builtin functions */ + double sqrt(doublereal), r_sign(real *, real *); + + /* Local variables */ + static integer i__, j, n2, n12, ii, n23, iq2; + static real temp; + extern doublereal snrm2_(integer *, real *, integer *); + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *), scopy_(integer *, real *, + integer *, real *, integer *), slaed4_(integer *, integer *, real + *, real *, real *, real *, real *, integer *); + extern doublereal slamc3_(real *, real *); + extern /* Subroutine */ int xerbla_(char *, integer *), slacpy_( + char *, integer *, integer *, real *, integer *, real *, integer * + ), slaset_(char *, integer *, integer *, real *, real *, + real *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + June 30, 1999 + + + Purpose + ======= + + SLAED3 finds the roots of the secular equation, as defined by the + values in D, W, and RHO, between 1 and K. It makes the + appropriate calls to SLAED4 and then updates the eigenvectors by + multiplying the matrix of eigenvectors of the pair of eigensystems + being combined by the matrix of eigenvectors of the K-by-K system + which is solved here. + + This code makes very mild assumptions about floating point + arithmetic. It will work on machines with a guard digit in + add/subtract, or on those binary machines without guard digits + which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or Cray-2. + It could conceivably fail on hexadecimal or decimal machines + without guard digits, but we know of none. + + Arguments + ========= + + K (input) INTEGER + The number of terms in the rational function to be solved by + SLAED4. K >= 0. + + N (input) INTEGER + The number of rows and columns in the Q matrix. + N >= K (deflation may result in N>K). + + N1 (input) INTEGER + The location of the last eigenvalue in the leading submatrix. + min(1,N) <= N1 <= N/2. + + D (output) REAL array, dimension (N) + D(I) contains the updated eigenvalues for + 1 <= I <= K. + + Q (output) REAL array, dimension (LDQ,N) + Initially the first K columns are used as workspace. + On output the columns 1 to K contain + the updated eigenvectors. + + LDQ (input) INTEGER + The leading dimension of the array Q. LDQ >= max(1,N). + + RHO (input) REAL + The value of the parameter in the rank one update equation. + RHO >= 0 required. + + DLAMDA (input/output) REAL array, dimension (K) + The first K elements of this array contain the old roots + of the deflated updating problem. These are the poles + of the secular equation. May be changed on output by + having lowest order bit set to zero on Cray X-MP, Cray Y-MP, + Cray-2, or Cray C-90, as described above. + + Q2 (input) REAL array, dimension (LDQ2, N) + The first K columns of this matrix contain the non-deflated + eigenvectors for the split problem. + + INDX (input) INTEGER array, dimension (N) + The permutation used to arrange the columns of the deflated + Q matrix into three groups (see SLAED2). + The rows of the eigenvectors found by SLAED4 must be likewise + permuted before the matrix multiply can take place. + + CTOT (input) INTEGER array, dimension (4) + A count of the total number of the various types of columns + in Q, as described in INDX. The fourth column type is any + column which has been deflated. + + W (input/output) REAL array, dimension (K) + The first K elements of this array contain the components + of the deflation-adjusted updating vector. Destroyed on + output. + + S (workspace) REAL array, dimension (N1 + 1)*K + Will contain the eigenvectors of the repaired matrix which + will be multiplied by the previously accumulated eigenvectors + to update the system. + + LDS (input) INTEGER + The leading dimension of S. LDS >= max(1,K). + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: if INFO = 1, an eigenvalue did not converge + + Further Details + =============== + + Based on contributions by + Jeff Rutter, Computer Science Division, University of California + at Berkeley, USA + Modified by Francoise Tisseur, University of Tennessee. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + q_dim1 = *ldq; + q_offset = 1 + q_dim1; + q -= q_offset; + --dlamda; + --q2; + --indx; + --ctot; + --w; + --s; + + /* Function Body */ + *info = 0; + + if (*k < 0) { + *info = -1; + } else if (*n < *k) { + *info = -2; + } else if (*ldq < max(1,*n)) { + *info = -6; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLAED3", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*k == 0) { + return 0; + } + +/* + Modify values DLAMDA(i) to make sure all DLAMDA(i)-DLAMDA(j) can + be computed with high relative accuracy (barring over/underflow). + This is a problem on machines without a guard digit in + add/subtract (Cray XMP, Cray YMP, Cray C 90 and Cray 2). + The following code replaces DLAMDA(I) by 2*DLAMDA(I)-DLAMDA(I), + which on any of these machines zeros out the bottommost + bit of DLAMDA(I) if it is 1; this makes the subsequent + subtractions DLAMDA(I)-DLAMDA(J) unproblematic when cancellation + occurs. On binary machines with a guard digit (almost all + machines) it does not change DLAMDA(I) at all. On hexadecimal + and decimal machines with a guard digit, it slightly + changes the bottommost bits of DLAMDA(I). It does not account + for hexadecimal or decimal machines without guard digits + (we know of none). We use a subroutine call to compute + 2*DLAMBDA(I) to prevent optimizing compilers from eliminating + this code. +*/ + + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + dlamda[i__] = slamc3_(&dlamda[i__], &dlamda[i__]) - dlamda[i__]; +/* L10: */ + } + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + slaed4_(k, &j, &dlamda[1], &w[1], &q[j * q_dim1 + 1], rho, &d__[j], + info); + +/* If the zero finder fails, the computation is terminated. */ + + if (*info != 0) { + goto L120; + } +/* L20: */ + } + + if (*k == 1) { + goto L110; + } + if (*k == 2) { + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + w[1] = q[j * q_dim1 + 1]; + w[2] = q[j * q_dim1 + 2]; + ii = indx[1]; + q[j * q_dim1 + 1] = w[ii]; + ii = indx[2]; + q[j * q_dim1 + 2] = w[ii]; +/* L30: */ + } + goto L110; + } + +/* Compute updated W. */ + + scopy_(k, &w[1], &c__1, &s[1], &c__1); + +/* Initialize W(I) = Q(I,I) */ + + i__1 = *ldq + 1; + scopy_(k, &q[q_offset], &i__1, &w[1], &c__1); + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = j - 1; + for (i__ = 1; i__ <= i__2; ++i__) { + w[i__] *= q[i__ + j * q_dim1] / (dlamda[i__] - dlamda[j]); +/* L40: */ + } + i__2 = *k; + for (i__ = j + 1; i__ <= i__2; ++i__) { + w[i__] *= q[i__ + j * q_dim1] / (dlamda[i__] - dlamda[j]); +/* L50: */ + } +/* L60: */ + } + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + r__1 = sqrt(-w[i__]); + w[i__] = r_sign(&r__1, &s[i__]); +/* L70: */ + } + +/* Compute eigenvectors of the modified rank-1 modification. */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = *k; + for (i__ = 1; i__ <= i__2; ++i__) { + s[i__] = w[i__] / q[i__ + j * q_dim1]; +/* L80: */ + } + temp = snrm2_(k, &s[1], &c__1); + i__2 = *k; + for (i__ = 1; i__ <= i__2; ++i__) { + ii = indx[i__]; + q[i__ + j * q_dim1] = s[ii] / temp; +/* L90: */ + } +/* L100: */ + } + +/* Compute the updated eigenvectors. */ + +L110: + + n2 = *n - *n1; + n12 = ctot[1] + ctot[2]; + n23 = ctot[2] + ctot[3]; + + slacpy_("A", &n23, k, &q[ctot[1] + 1 + q_dim1], ldq, &s[1], &n23); + iq2 = *n1 * n12 + 1; + if (n23 != 0) { + sgemm_("N", "N", &n2, k, &n23, &c_b15, &q2[iq2], &n2, &s[1], &n23, & + c_b29, &q[*n1 + 1 + q_dim1], ldq); + } else { + slaset_("A", &n2, k, &c_b29, &c_b29, &q[*n1 + 1 + q_dim1], ldq); + } + + slacpy_("A", &n12, k, &q[q_offset], ldq, &s[1], &n12); + if (n12 != 0) { + sgemm_("N", "N", n1, k, &n12, &c_b15, &q2[1], n1, &s[1], &n12, &c_b29, + &q[q_offset], ldq); + } else { + slaset_("A", n1, k, &c_b29, &c_b29, &q[q_dim1 + 1], ldq); + } + + +L120: + return 0; + +/* End of SLAED3 */ + +} /* slaed3_ */ + +/* Subroutine */ int slaed4_(integer *n, integer *i__, real *d__, real *z__, + real *delta, real *rho, real *dlam, integer *info) +{ + /* System generated locals */ + integer i__1; + real r__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real a, b, c__; + static integer j; + static real w; + static integer ii; + static real dw, zz[3]; + static integer ip1; + static real del, eta, phi, eps, tau, psi; + static integer iim1, iip1; + static real dphi, dpsi; + static integer iter; + static real temp, prew, temp1, dltlb, dltub, midpt; + static integer niter; + static logical swtch; + extern /* Subroutine */ int slaed5_(integer *, real *, real *, real *, + real *, real *), slaed6_(integer *, logical *, real *, real *, + real *, real *, real *, integer *); + static logical swtch3; + extern doublereal slamch_(char *); + static logical orgati; + static real erretm, rhoinv; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + December 23, 1999 + + + Purpose + ======= + + This subroutine computes the I-th updated eigenvalue of a symmetric + rank-one modification to a diagonal matrix whose elements are + given in the array d, and that + + D(i) < D(j) for i < j + + and that RHO > 0. This is arranged by the calling routine, and is + no loss in generality. The rank-one modified system is thus + + diag( D ) + RHO * Z * Z_transpose. + + where we assume the Euclidean norm of Z is 1. + + The method consists of approximating the rational functions in the + secular equation by simpler interpolating rational functions. + + Arguments + ========= + + N (input) INTEGER + The length of all arrays. + + I (input) INTEGER + The index of the eigenvalue to be computed. 1 <= I <= N. + + D (input) REAL array, dimension (N) + The original eigenvalues. It is assumed that they are in + order, D(I) < D(J) for I < J. + + Z (input) REAL array, dimension (N) + The components of the updating vector. + + DELTA (output) REAL array, dimension (N) + If N .ne. 1, DELTA contains (D(j) - lambda_I) in its j-th + component. If N = 1, then DELTA(1) = 1. The vector DELTA + contains the information necessary to construct the + eigenvectors. + + RHO (input) REAL + The scalar in the symmetric updating formula. + + DLAM (output) REAL + The computed lambda_I, the I-th updated eigenvalue. + + INFO (output) INTEGER + = 0: successful exit + > 0: if INFO = 1, the updating process failed. + + Internal Parameters + =================== + + Logical variable ORGATI (origin-at-i?) is used for distinguishing + whether D(i) or D(i+1) is treated as the origin. + + ORGATI = .true. origin at i + ORGATI = .false. origin at i+1 + + Logical variable SWTCH3 (switch-for-3-poles?) is for noting + if we are working with THREE poles! + + MAXIT is the maximum number of iterations allowed for each + eigenvalue. + + Further Details + =============== + + Based on contributions by + Ren-Cang Li, Computer Science Division, University of California + at Berkeley, USA + + ===================================================================== + + + Since this routine is called in an inner loop, we do no argument + checking. + + Quick return for N=1 and 2. +*/ + + /* Parameter adjustments */ + --delta; + --z__; + --d__; + + /* Function Body */ + *info = 0; + if (*n == 1) { + +/* Presumably, I=1 upon entry */ + + *dlam = d__[1] + *rho * z__[1] * z__[1]; + delta[1] = 1.f; + return 0; + } + if (*n == 2) { + slaed5_(i__, &d__[1], &z__[1], &delta[1], rho, dlam); + return 0; + } + +/* Compute machine epsilon */ + + eps = slamch_("Epsilon"); + rhoinv = 1.f / *rho; + +/* The case I = N */ + + if (*i__ == *n) { + +/* Initialize some basic variables */ + + ii = *n - 1; + niter = 1; + +/* Calculate initial guess */ + + midpt = *rho / 2.f; + +/* + If ||Z||_2 is not one, then TEMP should be set to + RHO * ||Z||_2^2 / TWO +*/ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[*i__] - midpt; +/* L10: */ + } + + psi = 0.f; + i__1 = *n - 2; + for (j = 1; j <= i__1; ++j) { + psi += z__[j] * z__[j] / delta[j]; +/* L20: */ + } + + c__ = rhoinv + psi; + w = c__ + z__[ii] * z__[ii] / delta[ii] + z__[*n] * z__[*n] / delta[* + n]; + + if (w <= 0.f) { + temp = z__[*n - 1] * z__[*n - 1] / (d__[*n] - d__[*n - 1] + *rho) + + z__[*n] * z__[*n] / *rho; + if (c__ <= temp) { + tau = *rho; + } else { + del = d__[*n] - d__[*n - 1]; + a = -c__ * del + z__[*n - 1] * z__[*n - 1] + z__[*n] * z__[*n] + ; + b = z__[*n] * z__[*n] * del; + if (a < 0.f) { + tau = b * 2.f / (sqrt(a * a + b * 4.f * c__) - a); + } else { + tau = (a + sqrt(a * a + b * 4.f * c__)) / (c__ * 2.f); + } + } + +/* + It can be proved that + D(N)+RHO/2 <= LAMBDA(N) < D(N)+TAU <= D(N)+RHO +*/ + + dltlb = midpt; + dltub = *rho; + } else { + del = d__[*n] - d__[*n - 1]; + a = -c__ * del + z__[*n - 1] * z__[*n - 1] + z__[*n] * z__[*n]; + b = z__[*n] * z__[*n] * del; + if (a < 0.f) { + tau = b * 2.f / (sqrt(a * a + b * 4.f * c__) - a); + } else { + tau = (a + sqrt(a * a + b * 4.f * c__)) / (c__ * 2.f); + } + +/* + It can be proved that + D(N) < D(N)+TAU < LAMBDA(N) < D(N)+RHO/2 +*/ + + dltlb = 0.f; + dltub = midpt; + } + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[*i__] - tau; +/* L30: */ + } + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L40: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / delta[*n]; + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8.f + erretm - phi + rhoinv + dabs(tau) * ( + dpsi + dphi); + + w = rhoinv + phi + psi; + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + *dlam = d__[*i__] + tau; + goto L250; + } + + if (w <= 0.f) { + dltlb = dmax(dltlb,tau); + } else { + dltub = dmin(dltub,tau); + } + +/* Calculate the new step */ + + ++niter; + c__ = w - delta[*n - 1] * dpsi - delta[*n] * dphi; + a = (delta[*n - 1] + delta[*n]) * w - delta[*n - 1] * delta[*n] * ( + dpsi + dphi); + b = delta[*n - 1] * delta[*n] * w; + if (c__ < 0.f) { + c__ = dabs(c__); + } + if (c__ == 0.f) { +/* + ETA = B/A + ETA = RHO - TAU +*/ + eta = dltub - tau; + } else if (a >= 0.f) { + eta = (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / ( + c__ * 2.f); + } else { + eta = b * 2.f / (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } + +/* + Note, eta should be positive if w is negative, and + eta should be negative otherwise. However, + if for some reason caused by roundoff, eta*w > 0, + we simply use one Newton step instead. This way + will guarantee eta*w < 0. +*/ + + if (w * eta > 0.f) { + eta = -w / (dpsi + dphi); + } + temp = tau + eta; + if (temp > dltub || temp < dltlb) { + if (w < 0.f) { + eta = (dltub - tau) / 2.f; + } else { + eta = (dltlb - tau) / 2.f; + } + } + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; +/* L50: */ + } + + tau += eta; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L60: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / delta[*n]; + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8.f + erretm - phi + rhoinv + dabs(tau) * ( + dpsi + dphi); + + w = rhoinv + phi + psi; + +/* Main loop to update the values of the array DELTA */ + + iter = niter + 1; + + for (niter = iter; niter <= 30; ++niter) { + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + *dlam = d__[*i__] + tau; + goto L250; + } + + if (w <= 0.f) { + dltlb = dmax(dltlb,tau); + } else { + dltub = dmin(dltub,tau); + } + +/* Calculate the new step */ + + c__ = w - delta[*n - 1] * dpsi - delta[*n] * dphi; + a = (delta[*n - 1] + delta[*n]) * w - delta[*n - 1] * delta[*n] * + (dpsi + dphi); + b = delta[*n - 1] * delta[*n] * w; + if (a >= 0.f) { + eta = (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / + (c__ * 2.f); + } else { + eta = b * 2.f / (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } + +/* + Note, eta should be positive if w is negative, and + eta should be negative otherwise. However, + if for some reason caused by roundoff, eta*w > 0, + we simply use one Newton step instead. This way + will guarantee eta*w < 0. +*/ + + if (w * eta > 0.f) { + eta = -w / (dpsi + dphi); + } + temp = tau + eta; + if (temp > dltub || temp < dltlb) { + if (w < 0.f) { + eta = (dltub - tau) / 2.f; + } else { + eta = (dltlb - tau) / 2.f; + } + } + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; +/* L70: */ + } + + tau += eta; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L80: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / delta[*n]; + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8.f + erretm - phi + rhoinv + dabs(tau) * + (dpsi + dphi); + + w = rhoinv + phi + psi; +/* L90: */ + } + +/* Return with INFO = 1, NITER = MAXIT and not converged */ + + *info = 1; + *dlam = d__[*i__] + tau; + goto L250; + +/* End for the case I = N */ + + } else { + +/* The case for I < N */ + + niter = 1; + ip1 = *i__ + 1; + +/* Calculate initial guess */ + + del = d__[ip1] - d__[*i__]; + midpt = del / 2.f; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[*i__] - midpt; +/* L100: */ + } + + psi = 0.f; + i__1 = *i__ - 1; + for (j = 1; j <= i__1; ++j) { + psi += z__[j] * z__[j] / delta[j]; +/* L110: */ + } + + phi = 0.f; + i__1 = *i__ + 2; + for (j = *n; j >= i__1; --j) { + phi += z__[j] * z__[j] / delta[j]; +/* L120: */ + } + c__ = rhoinv + psi + phi; + w = c__ + z__[*i__] * z__[*i__] / delta[*i__] + z__[ip1] * z__[ip1] / + delta[ip1]; + + if (w > 0.f) { + +/* + d(i)< the ith eigenvalue < (d(i)+d(i+1))/2 + + We choose d(i) as origin. +*/ + + orgati = TRUE_; + a = c__ * del + z__[*i__] * z__[*i__] + z__[ip1] * z__[ip1]; + b = z__[*i__] * z__[*i__] * del; + if (a > 0.f) { + tau = b * 2.f / (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } else { + tau = (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / + (c__ * 2.f); + } + dltlb = 0.f; + dltub = midpt; + } else { + +/* + (d(i)+d(i+1))/2 <= the ith eigenvalue < d(i+1) + + We choose d(i+1) as origin. +*/ + + orgati = FALSE_; + a = c__ * del - z__[*i__] * z__[*i__] - z__[ip1] * z__[ip1]; + b = z__[ip1] * z__[ip1] * del; + if (a < 0.f) { + tau = b * 2.f / (a - sqrt((r__1 = a * a + b * 4.f * c__, dabs( + r__1)))); + } else { + tau = -(a + sqrt((r__1 = a * a + b * 4.f * c__, dabs(r__1)))) + / (c__ * 2.f); + } + dltlb = -midpt; + dltub = 0.f; + } + + if (orgati) { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[*i__] - tau; +/* L130: */ + } + } else { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[ip1] - tau; +/* L140: */ + } + } + if (orgati) { + ii = *i__; + } else { + ii = *i__ + 1; + } + iim1 = ii - 1; + iip1 = ii + 1; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L150: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.f; + phi = 0.f; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[j] / delta[j]; + phi += z__[j] * temp; + dphi += temp * temp; + erretm += phi; +/* L160: */ + } + + w = rhoinv + phi + psi; + +/* + W is the value of the secular function with + its ii-th element removed. +*/ + + swtch3 = FALSE_; + if (orgati) { + if (w < 0.f) { + swtch3 = TRUE_; + } + } else { + if (w > 0.f) { + swtch3 = TRUE_; + } + } + if (ii == 1 || ii == *n) { + swtch3 = FALSE_; + } + + temp = z__[ii] / delta[ii]; + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w += temp; + erretm = (phi - psi) * 8.f + erretm + rhoinv * 2.f + dabs(temp) * 3.f + + dabs(tau) * dw; + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + if (orgati) { + *dlam = d__[*i__] + tau; + } else { + *dlam = d__[ip1] + tau; + } + goto L250; + } + + if (w <= 0.f) { + dltlb = dmax(dltlb,tau); + } else { + dltub = dmin(dltub,tau); + } + +/* Calculate the new step */ + + ++niter; + if (! swtch3) { + if (orgati) { +/* Computing 2nd power */ + r__1 = z__[*i__] / delta[*i__]; + c__ = w - delta[ip1] * dw - (d__[*i__] - d__[ip1]) * (r__1 * + r__1); + } else { +/* Computing 2nd power */ + r__1 = z__[ip1] / delta[ip1]; + c__ = w - delta[*i__] * dw - (d__[ip1] - d__[*i__]) * (r__1 * + r__1); + } + a = (delta[*i__] + delta[ip1]) * w - delta[*i__] * delta[ip1] * + dw; + b = delta[*i__] * delta[ip1] * w; + if (c__ == 0.f) { + if (a == 0.f) { + if (orgati) { + a = z__[*i__] * z__[*i__] + delta[ip1] * delta[ip1] * + (dpsi + dphi); + } else { + a = z__[ip1] * z__[ip1] + delta[*i__] * delta[*i__] * + (dpsi + dphi); + } + } + eta = b / a; + } else if (a <= 0.f) { + eta = (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / + (c__ * 2.f); + } else { + eta = b * 2.f / (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } + } else { + +/* Interpolation using THREE most relevant poles */ + + temp = rhoinv + psi + phi; + if (orgati) { + temp1 = z__[iim1] / delta[iim1]; + temp1 *= temp1; + c__ = temp - delta[iip1] * (dpsi + dphi) - (d__[iim1] - d__[ + iip1]) * temp1; + zz[0] = z__[iim1] * z__[iim1]; + zz[2] = delta[iip1] * delta[iip1] * (dpsi - temp1 + dphi); + } else { + temp1 = z__[iip1] / delta[iip1]; + temp1 *= temp1; + c__ = temp - delta[iim1] * (dpsi + dphi) - (d__[iip1] - d__[ + iim1]) * temp1; + zz[0] = delta[iim1] * delta[iim1] * (dpsi + (dphi - temp1)); + zz[2] = z__[iip1] * z__[iip1]; + } + zz[1] = z__[ii] * z__[ii]; + slaed6_(&niter, &orgati, &c__, &delta[iim1], zz, &w, &eta, info); + if (*info != 0) { + goto L250; + } + } + +/* + Note, eta should be positive if w is negative, and + eta should be negative otherwise. However, + if for some reason caused by roundoff, eta*w > 0, + we simply use one Newton step instead. This way + will guarantee eta*w < 0. +*/ + + if (w * eta >= 0.f) { + eta = -w / dw; + } + temp = tau + eta; + if (temp > dltub || temp < dltlb) { + if (w < 0.f) { + eta = (dltub - tau) / 2.f; + } else { + eta = (dltlb - tau) / 2.f; + } + } + + prew = w; + +/* L170: */ + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; +/* L180: */ + } + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L190: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.f; + phi = 0.f; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[j] / delta[j]; + phi += z__[j] * temp; + dphi += temp * temp; + erretm += phi; +/* L200: */ + } + + temp = z__[ii] / delta[ii]; + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w = rhoinv + phi + psi + temp; + erretm = (phi - psi) * 8.f + erretm + rhoinv * 2.f + dabs(temp) * 3.f + + (r__1 = tau + eta, dabs(r__1)) * dw; + + swtch = FALSE_; + if (orgati) { + if (-w > dabs(prew) / 10.f) { + swtch = TRUE_; + } + } else { + if (w > dabs(prew) / 10.f) { + swtch = TRUE_; + } + } + + tau += eta; + +/* Main loop to update the values of the array DELTA */ + + iter = niter + 1; + + for (niter = iter; niter <= 30; ++niter) { + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + if (orgati) { + *dlam = d__[*i__] + tau; + } else { + *dlam = d__[ip1] + tau; + } + goto L250; + } + + if (w <= 0.f) { + dltlb = dmax(dltlb,tau); + } else { + dltub = dmin(dltub,tau); + } + +/* Calculate the new step */ + + if (! swtch3) { + if (! swtch) { + if (orgati) { +/* Computing 2nd power */ + r__1 = z__[*i__] / delta[*i__]; + c__ = w - delta[ip1] * dw - (d__[*i__] - d__[ip1]) * ( + r__1 * r__1); + } else { +/* Computing 2nd power */ + r__1 = z__[ip1] / delta[ip1]; + c__ = w - delta[*i__] * dw - (d__[ip1] - d__[*i__]) * + (r__1 * r__1); + } + } else { + temp = z__[ii] / delta[ii]; + if (orgati) { + dpsi += temp * temp; + } else { + dphi += temp * temp; + } + c__ = w - delta[*i__] * dpsi - delta[ip1] * dphi; + } + a = (delta[*i__] + delta[ip1]) * w - delta[*i__] * delta[ip1] + * dw; + b = delta[*i__] * delta[ip1] * w; + if (c__ == 0.f) { + if (a == 0.f) { + if (! swtch) { + if (orgati) { + a = z__[*i__] * z__[*i__] + delta[ip1] * + delta[ip1] * (dpsi + dphi); + } else { + a = z__[ip1] * z__[ip1] + delta[*i__] * delta[ + *i__] * (dpsi + dphi); + } + } else { + a = delta[*i__] * delta[*i__] * dpsi + delta[ip1] + * delta[ip1] * dphi; + } + } + eta = b / a; + } else if (a <= 0.f) { + eta = (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)) + )) / (c__ * 2.f); + } else { + eta = b * 2.f / (a + sqrt((r__1 = a * a - b * 4.f * c__, + dabs(r__1)))); + } + } else { + +/* Interpolation using THREE most relevant poles */ + + temp = rhoinv + psi + phi; + if (swtch) { + c__ = temp - delta[iim1] * dpsi - delta[iip1] * dphi; + zz[0] = delta[iim1] * delta[iim1] * dpsi; + zz[2] = delta[iip1] * delta[iip1] * dphi; + } else { + if (orgati) { + temp1 = z__[iim1] / delta[iim1]; + temp1 *= temp1; + c__ = temp - delta[iip1] * (dpsi + dphi) - (d__[iim1] + - d__[iip1]) * temp1; + zz[0] = z__[iim1] * z__[iim1]; + zz[2] = delta[iip1] * delta[iip1] * (dpsi - temp1 + + dphi); + } else { + temp1 = z__[iip1] / delta[iip1]; + temp1 *= temp1; + c__ = temp - delta[iim1] * (dpsi + dphi) - (d__[iip1] + - d__[iim1]) * temp1; + zz[0] = delta[iim1] * delta[iim1] * (dpsi + (dphi - + temp1)); + zz[2] = z__[iip1] * z__[iip1]; + } + } + slaed6_(&niter, &orgati, &c__, &delta[iim1], zz, &w, &eta, + info); + if (*info != 0) { + goto L250; + } + } + +/* + Note, eta should be positive if w is negative, and + eta should be negative otherwise. However, + if for some reason caused by roundoff, eta*w > 0, + we simply use one Newton step instead. This way + will guarantee eta*w < 0. +*/ + + if (w * eta >= 0.f) { + eta = -w / dw; + } + temp = tau + eta; + if (temp > dltub || temp < dltlb) { + if (w < 0.f) { + eta = (dltub - tau) / 2.f; + } else { + eta = (dltlb - tau) / 2.f; + } + } + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; +/* L210: */ + } + + tau += eta; + prew = w; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L220: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.f; + phi = 0.f; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[j] / delta[j]; + phi += z__[j] * temp; + dphi += temp * temp; + erretm += phi; +/* L230: */ + } + + temp = z__[ii] / delta[ii]; + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w = rhoinv + phi + psi + temp; + erretm = (phi - psi) * 8.f + erretm + rhoinv * 2.f + dabs(temp) * + 3.f + dabs(tau) * dw; + if (w * prew > 0.f && dabs(w) > dabs(prew) / 10.f) { + swtch = ! swtch; + } + +/* L240: */ + } + +/* Return with INFO = 1, NITER = MAXIT and not converged */ + + *info = 1; + if (orgati) { + *dlam = d__[*i__] + tau; + } else { + *dlam = d__[ip1] + tau; + } + + } + +L250: + + return 0; + +/* End of SLAED4 */ + +} /* slaed4_ */ + +/* Subroutine */ int slaed5_(integer *i__, real *d__, real *z__, real *delta, + real *rho, real *dlam) +{ + /* System generated locals */ + real r__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real b, c__, w, del, tau, temp; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + September 30, 1994 + + + Purpose + ======= + + This subroutine computes the I-th eigenvalue of a symmetric rank-one + modification of a 2-by-2 diagonal matrix + + diag( D ) + RHO * Z * transpose(Z) . + + The diagonal elements in the array D are assumed to satisfy + + D(i) < D(j) for i < j . + + We also assume RHO > 0 and that the Euclidean norm of the vector + Z is one. + + Arguments + ========= + + I (input) INTEGER + The index of the eigenvalue to be computed. I = 1 or I = 2. + + D (input) REAL array, dimension (2) + The original eigenvalues. We assume D(1) < D(2). + + Z (input) REAL array, dimension (2) + The components of the updating vector. + + DELTA (output) REAL array, dimension (2) + The vector DELTA contains the information necessary + to construct the eigenvectors. + + RHO (input) REAL + The scalar in the symmetric updating formula. + + DLAM (output) REAL + The computed lambda_I, the I-th updated eigenvalue. + + Further Details + =============== + + Based on contributions by + Ren-Cang Li, Computer Science Division, University of California + at Berkeley, USA + + ===================================================================== +*/ + + + /* Parameter adjustments */ + --delta; + --z__; + --d__; + + /* Function Body */ + del = d__[2] - d__[1]; + if (*i__ == 1) { + w = *rho * 2.f * (z__[2] * z__[2] - z__[1] * z__[1]) / del + 1.f; + if (w > 0.f) { + b = del + *rho * (z__[1] * z__[1] + z__[2] * z__[2]); + c__ = *rho * z__[1] * z__[1] * del; + +/* B > ZERO, always */ + + tau = c__ * 2.f / (b + sqrt((r__1 = b * b - c__ * 4.f, dabs(r__1)) + )); + *dlam = d__[1] + tau; + delta[1] = -z__[1] / tau; + delta[2] = z__[2] / (del - tau); + } else { + b = -del + *rho * (z__[1] * z__[1] + z__[2] * z__[2]); + c__ = *rho * z__[2] * z__[2] * del; + if (b > 0.f) { + tau = c__ * -2.f / (b + sqrt(b * b + c__ * 4.f)); + } else { + tau = (b - sqrt(b * b + c__ * 4.f)) / 2.f; + } + *dlam = d__[2] + tau; + delta[1] = -z__[1] / (del + tau); + delta[2] = -z__[2] / tau; + } + temp = sqrt(delta[1] * delta[1] + delta[2] * delta[2]); + delta[1] /= temp; + delta[2] /= temp; + } else { + +/* Now I=2 */ + + b = -del + *rho * (z__[1] * z__[1] + z__[2] * z__[2]); + c__ = *rho * z__[2] * z__[2] * del; + if (b > 0.f) { + tau = (b + sqrt(b * b + c__ * 4.f)) / 2.f; + } else { + tau = c__ * 2.f / (-b + sqrt(b * b + c__ * 4.f)); + } + *dlam = d__[2] + tau; + delta[1] = -z__[1] / (del + tau); + delta[2] = -z__[2] / tau; + temp = sqrt(delta[1] * delta[1] + delta[2] * delta[2]); + delta[1] /= temp; + delta[2] /= temp; + } + return 0; + +/* End OF SLAED5 */ + +} /* slaed5_ */ + +/* Subroutine */ int slaed6_(integer *kniter, logical *orgati, real *rho, + real *d__, real *z__, real *finit, real *tau, integer *info) +{ + /* Initialized data */ + + static logical first = TRUE_; + + /* System generated locals */ + integer i__1; + real r__1, r__2, r__3, r__4; + + /* Builtin functions */ + double sqrt(doublereal), log(doublereal), pow_ri(real *, integer *); + + /* Local variables */ + static real a, b, c__, f; + static integer i__; + static real fc, df, ddf, eta, eps, base; + static integer iter; + static real temp, temp1, temp2, temp3, temp4; + static logical scale; + static integer niter; + static real small1, small2, sminv1, sminv2, dscale[3], sclfac; + extern doublereal slamch_(char *); + static real zscale[3], erretm, sclinv; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + June 30, 1999 + + + Purpose + ======= + + SLAED6 computes the positive or negative root (closest to the origin) + of + z(1) z(2) z(3) + f(x) = rho + --------- + ---------- + --------- + d(1)-x d(2)-x d(3)-x + + It is assumed that + + if ORGATI = .true. the root is between d(2) and d(3); + otherwise it is between d(1) and d(2) + + This routine will be called by SLAED4 when necessary. In most cases, + the root sought is the smallest in magnitude, though it might not be + in some extremely rare situations. + + Arguments + ========= + + KNITER (input) INTEGER + Refer to SLAED4 for its significance. + + ORGATI (input) LOGICAL + If ORGATI is true, the needed root is between d(2) and + d(3); otherwise it is between d(1) and d(2). See + SLAED4 for further details. + + RHO (input) REAL + Refer to the equation f(x) above. + + D (input) REAL array, dimension (3) + D satisfies d(1) < d(2) < d(3). + + Z (input) REAL array, dimension (3) + Each of the elements in z must be positive. + + FINIT (input) REAL + The value of f at 0. It is more accurate than the one + evaluated inside this routine (if someone wants to do + so). + + TAU (output) REAL + The root of the equation f(x). + + INFO (output) INTEGER + = 0: successful exit + > 0: if INFO = 1, failure to converge + + Further Details + =============== + + Based on contributions by + Ren-Cang Li, Computer Science Division, University of California + at Berkeley, USA + + ===================================================================== +*/ + + /* Parameter adjustments */ + --z__; + --d__; + + /* Function Body */ + + *info = 0; + + niter = 1; + *tau = 0.f; + if (*kniter == 2) { + if (*orgati) { + temp = (d__[3] - d__[2]) / 2.f; + c__ = *rho + z__[1] / (d__[1] - d__[2] - temp); + a = c__ * (d__[2] + d__[3]) + z__[2] + z__[3]; + b = c__ * d__[2] * d__[3] + z__[2] * d__[3] + z__[3] * d__[2]; + } else { + temp = (d__[1] - d__[2]) / 2.f; + c__ = *rho + z__[3] / (d__[3] - d__[2] - temp); + a = c__ * (d__[1] + d__[2]) + z__[1] + z__[2]; + b = c__ * d__[1] * d__[2] + z__[1] * d__[2] + z__[2] * d__[1]; + } +/* Computing MAX */ + r__1 = dabs(a), r__2 = dabs(b), r__1 = max(r__1,r__2), r__2 = dabs( + c__); + temp = dmax(r__1,r__2); + a /= temp; + b /= temp; + c__ /= temp; + if (c__ == 0.f) { + *tau = b / a; + } else if (a <= 0.f) { + *tau = (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / ( + c__ * 2.f); + } else { + *tau = b * 2.f / (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } + temp = *rho + z__[1] / (d__[1] - *tau) + z__[2] / (d__[2] - *tau) + + z__[3] / (d__[3] - *tau); + if (dabs(*finit) <= dabs(temp)) { + *tau = 0.f; + } + } + +/* + On first call to routine, get machine parameters for + possible scaling to avoid overflow +*/ + + if (first) { + eps = slamch_("Epsilon"); + base = slamch_("Base"); + i__1 = (integer) (log(slamch_("SafMin")) / log(base) / 3.f) + ; + small1 = pow_ri(&base, &i__1); + sminv1 = 1.f / small1; + small2 = small1 * small1; + sminv2 = sminv1 * sminv1; + first = FALSE_; + } + +/* + Determine if scaling of inputs necessary to avoid overflow + when computing 1/TEMP**3 +*/ + + if (*orgati) { +/* Computing MIN */ + r__3 = (r__1 = d__[2] - *tau, dabs(r__1)), r__4 = (r__2 = d__[3] - * + tau, dabs(r__2)); + temp = dmin(r__3,r__4); + } else { +/* Computing MIN */ + r__3 = (r__1 = d__[1] - *tau, dabs(r__1)), r__4 = (r__2 = d__[2] - * + tau, dabs(r__2)); + temp = dmin(r__3,r__4); + } + scale = FALSE_; + if (temp <= small1) { + scale = TRUE_; + if (temp <= small2) { + +/* Scale up by power of radix nearest 1/SAFMIN**(2/3) */ + + sclfac = sminv2; + sclinv = small2; + } else { + +/* Scale up by power of radix nearest 1/SAFMIN**(1/3) */ + + sclfac = sminv1; + sclinv = small1; + } + +/* Scaling up safe because D, Z, TAU scaled elsewhere to be O(1) */ + + for (i__ = 1; i__ <= 3; ++i__) { + dscale[i__ - 1] = d__[i__] * sclfac; + zscale[i__ - 1] = z__[i__] * sclfac; +/* L10: */ + } + *tau *= sclfac; + } else { + +/* Copy D and Z to DSCALE and ZSCALE */ + + for (i__ = 1; i__ <= 3; ++i__) { + dscale[i__ - 1] = d__[i__]; + zscale[i__ - 1] = z__[i__]; +/* L20: */ + } + } + + fc = 0.f; + df = 0.f; + ddf = 0.f; + for (i__ = 1; i__ <= 3; ++i__) { + temp = 1.f / (dscale[i__ - 1] - *tau); + temp1 = zscale[i__ - 1] * temp; + temp2 = temp1 * temp; + temp3 = temp2 * temp; + fc += temp1 / dscale[i__ - 1]; + df += temp2; + ddf += temp3; +/* L30: */ + } + f = *finit + *tau * fc; + + if (dabs(f) <= 0.f) { + goto L60; + } + +/* + Iteration begins + + It is not hard to see that + + 1) Iterations will go up monotonically + if FINIT < 0; + + 2) Iterations will go down monotonically + if FINIT > 0. +*/ + + iter = niter + 1; + + for (niter = iter; niter <= 20; ++niter) { + + if (*orgati) { + temp1 = dscale[1] - *tau; + temp2 = dscale[2] - *tau; + } else { + temp1 = dscale[0] - *tau; + temp2 = dscale[1] - *tau; + } + a = (temp1 + temp2) * f - temp1 * temp2 * df; + b = temp1 * temp2 * f; + c__ = f - (temp1 + temp2) * df + temp1 * temp2 * ddf; +/* Computing MAX */ + r__1 = dabs(a), r__2 = dabs(b), r__1 = max(r__1,r__2), r__2 = dabs( + c__); + temp = dmax(r__1,r__2); + a /= temp; + b /= temp; + c__ /= temp; + if (c__ == 0.f) { + eta = b / a; + } else if (a <= 0.f) { + eta = (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / ( + c__ * 2.f); + } else { + eta = b * 2.f / (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } + if (f * eta >= 0.f) { + eta = -f / df; + } + + temp = eta + *tau; + if (*orgati) { + if (eta > 0.f && temp >= dscale[2]) { + eta = (dscale[2] - *tau) / 2.f; + } + if (eta < 0.f && temp <= dscale[1]) { + eta = (dscale[1] - *tau) / 2.f; + } + } else { + if (eta > 0.f && temp >= dscale[1]) { + eta = (dscale[1] - *tau) / 2.f; + } + if (eta < 0.f && temp <= dscale[0]) { + eta = (dscale[0] - *tau) / 2.f; + } + } + *tau += eta; + + fc = 0.f; + erretm = 0.f; + df = 0.f; + ddf = 0.f; + for (i__ = 1; i__ <= 3; ++i__) { + temp = 1.f / (dscale[i__ - 1] - *tau); + temp1 = zscale[i__ - 1] * temp; + temp2 = temp1 * temp; + temp3 = temp2 * temp; + temp4 = temp1 / dscale[i__ - 1]; + fc += temp4; + erretm += dabs(temp4); + df += temp2; + ddf += temp3; +/* L40: */ + } + f = *finit + *tau * fc; + erretm = (dabs(*finit) + dabs(*tau) * erretm) * 8.f + dabs(*tau) * df; + if (dabs(f) <= eps * erretm) { + goto L60; + } +/* L50: */ + } + *info = 1; +L60: + +/* Undo scaling */ + + if (scale) { + *tau *= sclinv; + } + return 0; + +/* End of SLAED6 */ + +} /* slaed6_ */ + +/* Subroutine */ int slaed7_(integer *icompq, integer *n, integer *qsiz, + integer *tlvls, integer *curlvl, integer *curpbm, real *d__, real *q, + integer *ldq, integer *indxq, real *rho, integer *cutpnt, real * + qstore, integer *qptr, integer *prmptr, integer *perm, integer * + givptr, integer *givcol, real *givnum, real *work, integer *iwork, + integer *info) +{ + /* System generated locals */ + integer q_dim1, q_offset, i__1, i__2; + + /* Builtin functions */ + integer pow_ii(integer *, integer *); + + /* Local variables */ + static integer i__, k, n1, n2, is, iw, iz, iq2, ptr, ldq2, indx, curr, + indxc; + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *); + static integer indxp; + extern /* Subroutine */ int slaed8_(integer *, integer *, integer *, + integer *, real *, real *, integer *, integer *, real *, integer * + , real *, real *, real *, integer *, real *, integer *, integer *, + integer *, real *, integer *, integer *, integer *), slaed9_( + integer *, integer *, integer *, integer *, real *, real *, + integer *, real *, real *, real *, real *, integer *, integer *), + slaeda_(integer *, integer *, integer *, integer *, integer *, + integer *, integer *, integer *, real *, real *, integer *, real * + , real *, integer *); + static integer idlmda; + extern /* Subroutine */ int xerbla_(char *, integer *), slamrg_( + integer *, integer *, real *, integer *, integer *, integer *); + static integer coltyp; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + September 30, 1994 + + + Purpose + ======= + + SLAED7 computes the updated eigensystem of a diagonal + matrix after modification by a rank-one symmetric matrix. This + routine is used only for the eigenproblem which requires all + eigenvalues and optionally eigenvectors of a dense symmetric matrix + that has been reduced to tridiagonal form. SLAED1 handles + the case in which all eigenvalues and eigenvectors of a symmetric + tridiagonal matrix are desired. + + T = Q(in) ( D(in) + RHO * Z*Z' ) Q'(in) = Q(out) * D(out) * Q'(out) + + where Z = Q'u, u is a vector of length N with ones in the + CUTPNT and CUTPNT + 1 th elements and zeros elsewhere. + + The eigenvectors of the original matrix are stored in Q, and the + eigenvalues are in D. The algorithm consists of three stages: + + The first stage consists of deflating the size of the problem + when there are multiple eigenvalues or if there is a zero in + the Z vector. For each such occurence the dimension of the + secular equation problem is reduced by one. This stage is + performed by the routine SLAED8. + + The second stage consists of calculating the updated + eigenvalues. This is done by finding the roots of the secular + equation via the routine SLAED4 (as called by SLAED9). + This routine also calculates the eigenvectors of the current + problem. + + The final stage consists of computing the updated eigenvectors + directly using the updated eigenvalues. The eigenvectors for + the current problem are multiplied with the eigenvectors from + the overall problem. + + Arguments + ========= + + ICOMPQ (input) INTEGER + = 0: Compute eigenvalues only. + = 1: Compute eigenvectors of original dense symmetric matrix + also. On entry, Q contains the orthogonal matrix used + to reduce the original matrix to tridiagonal form. + + N (input) INTEGER + The dimension of the symmetric tridiagonal matrix. N >= 0. + + QSIZ (input) INTEGER + The dimension of the orthogonal matrix used to reduce + the full matrix to tridiagonal form. QSIZ >= N if ICOMPQ = 1. + + TLVLS (input) INTEGER + The total number of merging levels in the overall divide and + conquer tree. + + CURLVL (input) INTEGER + The current level in the overall merge routine, + 0 <= CURLVL <= TLVLS. + + CURPBM (input) INTEGER + The current problem in the current level in the overall + merge routine (counting from upper left to lower right). + + D (input/output) REAL array, dimension (N) + On entry, the eigenvalues of the rank-1-perturbed matrix. + On exit, the eigenvalues of the repaired matrix. + + Q (input/output) REAL array, dimension (LDQ, N) + On entry, the eigenvectors of the rank-1-perturbed matrix. + On exit, the eigenvectors of the repaired tridiagonal matrix. + + LDQ (input) INTEGER + The leading dimension of the array Q. LDQ >= max(1,N). + + INDXQ (output) INTEGER array, dimension (N) + The permutation which will reintegrate the subproblem just + solved back into sorted order, i.e., D( INDXQ( I = 1, N ) ) + will be in ascending order. + + RHO (input) REAL + The subdiagonal element used to create the rank-1 + modification. + + CUTPNT (input) INTEGER + Contains the location of the last eigenvalue in the leading + sub-matrix. min(1,N) <= CUTPNT <= N. + + QSTORE (input/output) REAL array, dimension (N**2+1) + Stores eigenvectors of submatrices encountered during + divide and conquer, packed together. QPTR points to + beginning of the submatrices. + + QPTR (input/output) INTEGER array, dimension (N+2) + List of indices pointing to beginning of submatrices stored + in QSTORE. The submatrices are numbered starting at the + bottom left of the divide and conquer tree, from left to + right and bottom to top. + + PRMPTR (input) INTEGER array, dimension (N lg N) + Contains a list of pointers which indicate where in PERM a + level's permutation is stored. PRMPTR(i+1) - PRMPTR(i) + indicates the size of the permutation and also the size of + the full, non-deflated problem. + + PERM (input) INTEGER array, dimension (N lg N) + Contains the permutations (from deflation and sorting) to be + applied to each eigenblock. + + GIVPTR (input) INTEGER array, dimension (N lg N) + Contains a list of pointers which indicate where in GIVCOL a + level's Givens rotations are stored. GIVPTR(i+1) - GIVPTR(i) + indicates the number of Givens rotations. + + GIVCOL (input) INTEGER array, dimension (2, N lg N) + Each pair of numbers indicates a pair of columns to take place + in a Givens rotation. + + GIVNUM (input) REAL array, dimension (2, N lg N) + Each number indicates the S value to be used in the + corresponding Givens rotation. + + WORK (workspace) REAL array, dimension (3*N+QSIZ*N) + + IWORK (workspace) INTEGER array, dimension (4*N) + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: if INFO = 1, an eigenvalue did not converge + + Further Details + =============== + + Based on contributions by + Jeff Rutter, Computer Science Division, University of California + at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + q_dim1 = *ldq; + q_offset = 1 + q_dim1; + q -= q_offset; + --indxq; + --qstore; + --qptr; + --prmptr; + --perm; + --givptr; + givcol -= 3; + givnum -= 3; + --work; + --iwork; + + /* Function Body */ + *info = 0; + + if (*icompq < 0 || *icompq > 1) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*icompq == 1 && *qsiz < *n) { + *info = -4; + } else if (*ldq < max(1,*n)) { + *info = -9; + } else if (min(1,*n) > *cutpnt || *n < *cutpnt) { + *info = -12; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLAED7", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + +/* + The following values are for bookkeeping purposes only. They are + integer pointers which indicate the portion of the workspace + used by a particular array in SLAED8 and SLAED9. +*/ + + if (*icompq == 1) { + ldq2 = *qsiz; + } else { + ldq2 = *n; + } + + iz = 1; + idlmda = iz + *n; + iw = idlmda + *n; + iq2 = iw + *n; + is = iq2 + *n * ldq2; + + indx = 1; + indxc = indx + *n; + coltyp = indxc + *n; + indxp = coltyp + *n; + +/* + Form the z-vector which consists of the last row of Q_1 and the + first row of Q_2. +*/ + + ptr = pow_ii(&c__2, tlvls) + 1; + i__1 = *curlvl - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + i__2 = *tlvls - i__; + ptr += pow_ii(&c__2, &i__2); +/* L10: */ + } + curr = ptr + *curpbm; + slaeda_(n, tlvls, curlvl, curpbm, &prmptr[1], &perm[1], &givptr[1], & + givcol[3], &givnum[3], &qstore[1], &qptr[1], &work[iz], &work[iz + + *n], info); + +/* + When solving the final problem, we no longer need the stored data, + so we will overwrite the data from this level onto the previously + used storage space. +*/ + + if (*curlvl == *tlvls) { + qptr[curr] = 1; + prmptr[curr] = 1; + givptr[curr] = 1; + } + +/* Sort and Deflate eigenvalues. */ + + slaed8_(icompq, &k, n, qsiz, &d__[1], &q[q_offset], ldq, &indxq[1], rho, + cutpnt, &work[iz], &work[idlmda], &work[iq2], &ldq2, &work[iw], & + perm[prmptr[curr]], &givptr[curr + 1], &givcol[(givptr[curr] << 1) + + 1], &givnum[(givptr[curr] << 1) + 1], &iwork[indxp], &iwork[ + indx], info); + prmptr[curr + 1] = prmptr[curr] + *n; + givptr[curr + 1] += givptr[curr]; + +/* Solve Secular Equation. */ + + if (k != 0) { + slaed9_(&k, &c__1, &k, n, &d__[1], &work[is], &k, rho, &work[idlmda], + &work[iw], &qstore[qptr[curr]], &k, info); + if (*info != 0) { + goto L30; + } + if (*icompq == 1) { + sgemm_("N", "N", qsiz, &k, &k, &c_b15, &work[iq2], &ldq2, &qstore[ + qptr[curr]], &k, &c_b29, &q[q_offset], ldq); + } +/* Computing 2nd power */ + i__1 = k; + qptr[curr + 1] = qptr[curr] + i__1 * i__1; + +/* Prepare the INDXQ sorting permutation. */ + + n1 = k; + n2 = *n - k; + slamrg_(&n1, &n2, &d__[1], &c__1, &c_n1, &indxq[1]); + } else { + qptr[curr + 1] = qptr[curr]; + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + indxq[i__] = i__; +/* L20: */ + } + } + +L30: + return 0; + +/* End of SLAED7 */ + +} /* slaed7_ */ + +/* Subroutine */ int slaed8_(integer *icompq, integer *k, integer *n, integer + *qsiz, real *d__, real *q, integer *ldq, integer *indxq, real *rho, + integer *cutpnt, real *z__, real *dlamda, real *q2, integer *ldq2, + real *w, integer *perm, integer *givptr, integer *givcol, real * + givnum, integer *indxp, integer *indx, integer *info) +{ + /* System generated locals */ + integer q_dim1, q_offset, q2_dim1, q2_offset, i__1; + real r__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real c__; + static integer i__, j; + static real s, t; + static integer k2, n1, n2, jp, n1p1; + static real eps, tau, tol; + static integer jlam, imax, jmax; + extern /* Subroutine */ int srot_(integer *, real *, integer *, real *, + integer *, real *, real *), sscal_(integer *, real *, real *, + integer *), scopy_(integer *, real *, integer *, real *, integer * + ); + extern doublereal slapy2_(real *, real *), slamch_(char *); + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer isamax_(integer *, real *, integer *); + extern /* Subroutine */ int slamrg_(integer *, integer *, real *, integer + *, integer *, integer *), slacpy_(char *, integer *, integer *, + real *, integer *, real *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + September 30, 1994 + + + Purpose + ======= + + SLAED8 merges the two sets of eigenvalues together into a single + sorted set. Then it tries to deflate the size of the problem. + There are two ways in which deflation can occur: when two or more + eigenvalues are close together or if there is a tiny element in the + Z vector. For each such occurrence the order of the related secular + equation problem is reduced by one. + + Arguments + ========= + + ICOMPQ (input) INTEGER + = 0: Compute eigenvalues only. + = 1: Compute eigenvectors of original dense symmetric matrix + also. On entry, Q contains the orthogonal matrix used + to reduce the original matrix to tridiagonal form. + + K (output) INTEGER + The number of non-deflated eigenvalues, and the order of the + related secular equation. + + N (input) INTEGER + The dimension of the symmetric tridiagonal matrix. N >= 0. + + QSIZ (input) INTEGER + The dimension of the orthogonal matrix used to reduce + the full matrix to tridiagonal form. QSIZ >= N if ICOMPQ = 1. + + D (input/output) REAL array, dimension (N) + On entry, the eigenvalues of the two submatrices to be + combined. On exit, the trailing (N-K) updated eigenvalues + (those which were deflated) sorted into increasing order. + + Q (input/output) REAL array, dimension (LDQ,N) + If ICOMPQ = 0, Q is not referenced. Otherwise, + on entry, Q contains the eigenvectors of the partially solved + system which has been previously updated in matrix + multiplies with other partially solved eigensystems. + On exit, Q contains the trailing (N-K) updated eigenvectors + (those which were deflated) in its last N-K columns. + + LDQ (input) INTEGER + The leading dimension of the array Q. LDQ >= max(1,N). + + INDXQ (input) INTEGER array, dimension (N) + The permutation which separately sorts the two sub-problems + in D into ascending order. Note that elements in the second + half of this permutation must first have CUTPNT added to + their values in order to be accurate. + + RHO (input/output) REAL + On entry, the off-diagonal element associated with the rank-1 + cut which originally split the two submatrices which are now + being recombined. + On exit, RHO has been modified to the value required by + SLAED3. + + CUTPNT (input) INTEGER + The location of the last eigenvalue in the leading + sub-matrix. min(1,N) <= CUTPNT <= N. + + Z (input) REAL array, dimension (N) + On entry, Z contains the updating vector (the last row of + the first sub-eigenvector matrix and the first row of the + second sub-eigenvector matrix). + On exit, the contents of Z are destroyed by the updating + process. + + DLAMDA (output) REAL array, dimension (N) + A copy of the first K eigenvalues which will be used by + SLAED3 to form the secular equation. + + Q2 (output) REAL array, dimension (LDQ2,N) + If ICOMPQ = 0, Q2 is not referenced. Otherwise, + a copy of the first K eigenvectors which will be used by + SLAED7 in a matrix multiply (SGEMM) to update the new + eigenvectors. + + LDQ2 (input) INTEGER + The leading dimension of the array Q2. LDQ2 >= max(1,N). + + W (output) REAL array, dimension (N) + The first k values of the final deflation-altered z-vector and + will be passed to SLAED3. + + PERM (output) INTEGER array, dimension (N) + The permutations (from deflation and sorting) to be applied + to each eigenblock. + + GIVPTR (output) INTEGER + The number of Givens rotations which took place in this + subproblem. + + GIVCOL (output) INTEGER array, dimension (2, N) + Each pair of numbers indicates a pair of columns to take place + in a Givens rotation. + + GIVNUM (output) REAL array, dimension (2, N) + Each number indicates the S value to be used in the + corresponding Givens rotation. + + INDXP (workspace) INTEGER array, dimension (N) + The permutation used to place deflated values of D at the end + of the array. INDXP(1:K) points to the nondeflated D-values + and INDXP(K+1:N) points to the deflated eigenvalues. + + INDX (workspace) INTEGER array, dimension (N) + The permutation used to sort the contents of D into ascending + order. + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + + Further Details + =============== + + Based on contributions by + Jeff Rutter, Computer Science Division, University of California + at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + q_dim1 = *ldq; + q_offset = 1 + q_dim1; + q -= q_offset; + --indxq; + --z__; + --dlamda; + q2_dim1 = *ldq2; + q2_offset = 1 + q2_dim1; + q2 -= q2_offset; + --w; + --perm; + givcol -= 3; + givnum -= 3; + --indxp; + --indx; + + /* Function Body */ + *info = 0; + + if (*icompq < 0 || *icompq > 1) { + *info = -1; + } else if (*n < 0) { + *info = -3; + } else if (*icompq == 1 && *qsiz < *n) { + *info = -4; + } else if (*ldq < max(1,*n)) { + *info = -7; + } else if (*cutpnt < min(1,*n) || *cutpnt > *n) { + *info = -10; + } else if (*ldq2 < max(1,*n)) { + *info = -14; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLAED8", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + + n1 = *cutpnt; + n2 = *n - n1; + n1p1 = n1 + 1; + + if (*rho < 0.f) { + sscal_(&n2, &c_b151, &z__[n1p1], &c__1); + } + +/* Normalize z so that norm(z) = 1 */ + + t = 1.f / sqrt(2.f); + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + indx[j] = j; +/* L10: */ + } + sscal_(n, &t, &z__[1], &c__1); + *rho = (r__1 = *rho * 2.f, dabs(r__1)); + +/* Sort the eigenvalues into increasing order */ + + i__1 = *n; + for (i__ = *cutpnt + 1; i__ <= i__1; ++i__) { + indxq[i__] += *cutpnt; +/* L20: */ + } + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + dlamda[i__] = d__[indxq[i__]]; + w[i__] = z__[indxq[i__]]; +/* L30: */ + } + i__ = 1; + j = *cutpnt + 1; + slamrg_(&n1, &n2, &dlamda[1], &c__1, &c__1, &indx[1]); + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + d__[i__] = dlamda[indx[i__]]; + z__[i__] = w[indx[i__]]; +/* L40: */ + } + +/* Calculate the allowable deflation tolerence */ + + imax = isamax_(n, &z__[1], &c__1); + jmax = isamax_(n, &d__[1], &c__1); + eps = slamch_("Epsilon"); + tol = eps * 8.f * (r__1 = d__[jmax], dabs(r__1)); + +/* + If the rank-1 modifier is small enough, no more needs to be done + except to reorganize Q so that its columns correspond with the + elements in D. +*/ + + if (*rho * (r__1 = z__[imax], dabs(r__1)) <= tol) { + *k = 0; + if (*icompq == 0) { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + perm[j] = indxq[indx[j]]; +/* L50: */ + } + } else { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + perm[j] = indxq[indx[j]]; + scopy_(qsiz, &q[perm[j] * q_dim1 + 1], &c__1, &q2[j * q2_dim1 + + 1], &c__1); +/* L60: */ + } + slacpy_("A", qsiz, n, &q2[q2_dim1 + 1], ldq2, &q[q_dim1 + 1], ldq); + } + return 0; + } + +/* + If there are multiple eigenvalues then the problem deflates. Here + the number of equal eigenvalues are found. As each equal + eigenvalue is found, an elementary reflector is computed to rotate + the corresponding eigensubspace so that the corresponding + components of Z are zero in this new basis. +*/ + + *k = 0; + *givptr = 0; + k2 = *n + 1; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + if (*rho * (r__1 = z__[j], dabs(r__1)) <= tol) { + +/* Deflate due to small z component. */ + + --k2; + indxp[k2] = j; + if (j == *n) { + goto L110; + } + } else { + jlam = j; + goto L80; + } +/* L70: */ + } +L80: + ++j; + if (j > *n) { + goto L100; + } + if (*rho * (r__1 = z__[j], dabs(r__1)) <= tol) { + +/* Deflate due to small z component. */ + + --k2; + indxp[k2] = j; + } else { + +/* Check if eigenvalues are close enough to allow deflation. */ + + s = z__[jlam]; + c__ = z__[j]; + +/* + Find sqrt(a**2+b**2) without overflow or + destructive underflow. +*/ + + tau = slapy2_(&c__, &s); + t = d__[j] - d__[jlam]; + c__ /= tau; + s = -s / tau; + if ((r__1 = t * c__ * s, dabs(r__1)) <= tol) { + +/* Deflation is possible. */ + + z__[j] = tau; + z__[jlam] = 0.f; + +/* Record the appropriate Givens rotation */ + + ++(*givptr); + givcol[(*givptr << 1) + 1] = indxq[indx[jlam]]; + givcol[(*givptr << 1) + 2] = indxq[indx[j]]; + givnum[(*givptr << 1) + 1] = c__; + givnum[(*givptr << 1) + 2] = s; + if (*icompq == 1) { + srot_(qsiz, &q[indxq[indx[jlam]] * q_dim1 + 1], &c__1, &q[ + indxq[indx[j]] * q_dim1 + 1], &c__1, &c__, &s); + } + t = d__[jlam] * c__ * c__ + d__[j] * s * s; + d__[j] = d__[jlam] * s * s + d__[j] * c__ * c__; + d__[jlam] = t; + --k2; + i__ = 1; +L90: + if (k2 + i__ <= *n) { + if (d__[jlam] < d__[indxp[k2 + i__]]) { + indxp[k2 + i__ - 1] = indxp[k2 + i__]; + indxp[k2 + i__] = jlam; + ++i__; + goto L90; + } else { + indxp[k2 + i__ - 1] = jlam; + } + } else { + indxp[k2 + i__ - 1] = jlam; + } + jlam = j; + } else { + ++(*k); + w[*k] = z__[jlam]; + dlamda[*k] = d__[jlam]; + indxp[*k] = jlam; + jlam = j; + } + } + goto L80; +L100: + +/* Record the last eigenvalue. */ + + ++(*k); + w[*k] = z__[jlam]; + dlamda[*k] = d__[jlam]; + indxp[*k] = jlam; + +L110: + +/* + Sort the eigenvalues and corresponding eigenvectors into DLAMDA + and Q2 respectively. The eigenvalues/vectors which were not + deflated go into the first K slots of DLAMDA and Q2 respectively, + while those which were deflated go into the last N - K slots. +*/ + + if (*icompq == 0) { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + jp = indxp[j]; + dlamda[j] = d__[jp]; + perm[j] = indxq[indx[jp]]; +/* L120: */ + } + } else { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + jp = indxp[j]; + dlamda[j] = d__[jp]; + perm[j] = indxq[indx[jp]]; + scopy_(qsiz, &q[perm[j] * q_dim1 + 1], &c__1, &q2[j * q2_dim1 + 1] + , &c__1); +/* L130: */ + } + } + +/* + The deflated eigenvalues and their corresponding vectors go back + into the last N - K slots of D and Q respectively. +*/ + + if (*k < *n) { + if (*icompq == 0) { + i__1 = *n - *k; + scopy_(&i__1, &dlamda[*k + 1], &c__1, &d__[*k + 1], &c__1); + } else { + i__1 = *n - *k; + scopy_(&i__1, &dlamda[*k + 1], &c__1, &d__[*k + 1], &c__1); + i__1 = *n - *k; + slacpy_("A", qsiz, &i__1, &q2[(*k + 1) * q2_dim1 + 1], ldq2, &q[(* + k + 1) * q_dim1 + 1], ldq); + } + } + + return 0; + +/* End of SLAED8 */ + +} /* slaed8_ */ + +/* Subroutine */ int slaed9_(integer *k, integer *kstart, integer *kstop, + integer *n, real *d__, real *q, integer *ldq, real *rho, real *dlamda, + real *w, real *s, integer *lds, integer *info) +{ + /* System generated locals */ + integer q_dim1, q_offset, s_dim1, s_offset, i__1, i__2; + real r__1; + + /* Builtin functions */ + double sqrt(doublereal), r_sign(real *, real *); + + /* Local variables */ + static integer i__, j; + static real temp; + extern doublereal snrm2_(integer *, real *, integer *); + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *), slaed4_(integer *, integer *, real *, real *, real *, + real *, real *, integer *); + extern doublereal slamc3_(real *, real *); + extern /* Subroutine */ int xerbla_(char *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + September 30, 1994 + + + Purpose + ======= + + SLAED9 finds the roots of the secular equation, as defined by the + values in D, Z, and RHO, between KSTART and KSTOP. It makes the + appropriate calls to SLAED4 and then stores the new matrix of + eigenvectors for use in calculating the next level of Z vectors. + + Arguments + ========= + + K (input) INTEGER + The number of terms in the rational function to be solved by + SLAED4. K >= 0. + + KSTART (input) INTEGER + KSTOP (input) INTEGER + The updated eigenvalues Lambda(I), KSTART <= I <= KSTOP + are to be computed. 1 <= KSTART <= KSTOP <= K. + + N (input) INTEGER + The number of rows and columns in the Q matrix. + N >= K (delation may result in N > K). + + D (output) REAL array, dimension (N) + D(I) contains the updated eigenvalues + for KSTART <= I <= KSTOP. + + Q (workspace) REAL array, dimension (LDQ,N) + + LDQ (input) INTEGER + The leading dimension of the array Q. LDQ >= max( 1, N ). + + RHO (input) REAL + The value of the parameter in the rank one update equation. + RHO >= 0 required. + + DLAMDA (input) REAL array, dimension (K) + The first K elements of this array contain the old roots + of the deflated updating problem. These are the poles + of the secular equation. + + W (input) REAL array, dimension (K) + The first K elements of this array contain the components + of the deflation-adjusted updating vector. + + S (output) REAL array, dimension (LDS, K) + Will contain the eigenvectors of the repaired matrix which + will be stored for subsequent Z vector calculation and + multiplied by the previously accumulated eigenvectors + to update the system. + + LDS (input) INTEGER + The leading dimension of S. LDS >= max( 1, K ). + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: if INFO = 1, an eigenvalue did not converge + + Further Details + =============== + + Based on contributions by + Jeff Rutter, Computer Science Division, University of California + at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + q_dim1 = *ldq; + q_offset = 1 + q_dim1; + q -= q_offset; + --dlamda; + --w; + s_dim1 = *lds; + s_offset = 1 + s_dim1; + s -= s_offset; + + /* Function Body */ + *info = 0; + + if (*k < 0) { + *info = -1; + } else if (*kstart < 1 || *kstart > max(1,*k)) { + *info = -2; + } else if (max(1,*kstop) < *kstart || *kstop > max(1,*k)) { + *info = -3; + } else if (*n < *k) { + *info = -4; + } else if (*ldq < max(1,*k)) { + *info = -7; + } else if (*lds < max(1,*k)) { + *info = -12; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLAED9", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*k == 0) { + return 0; + } + +/* + Modify values DLAMDA(i) to make sure all DLAMDA(i)-DLAMDA(j) can + be computed with high relative accuracy (barring over/underflow). + This is a problem on machines without a guard digit in + add/subtract (Cray XMP, Cray YMP, Cray C 90 and Cray 2). + The following code replaces DLAMDA(I) by 2*DLAMDA(I)-DLAMDA(I), + which on any of these machines zeros out the bottommost + bit of DLAMDA(I) if it is 1; this makes the subsequent + subtractions DLAMDA(I)-DLAMDA(J) unproblematic when cancellation + occurs. On binary machines with a guard digit (almost all + machines) it does not change DLAMDA(I) at all. On hexadecimal + and decimal machines with a guard digit, it slightly + changes the bottommost bits of DLAMDA(I). It does not account + for hexadecimal or decimal machines without guard digits + (we know of none). We use a subroutine call to compute + 2*DLAMBDA(I) to prevent optimizing compilers from eliminating + this code. +*/ + + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + dlamda[i__] = slamc3_(&dlamda[i__], &dlamda[i__]) - dlamda[i__]; +/* L10: */ + } + + i__1 = *kstop; + for (j = *kstart; j <= i__1; ++j) { + slaed4_(k, &j, &dlamda[1], &w[1], &q[j * q_dim1 + 1], rho, &d__[j], + info); + +/* If the zero finder fails, the computation is terminated. */ + + if (*info != 0) { + goto L120; + } +/* L20: */ + } + + if (*k == 1 || *k == 2) { + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + i__2 = *k; + for (j = 1; j <= i__2; ++j) { + s[j + i__ * s_dim1] = q[j + i__ * q_dim1]; +/* L30: */ + } +/* L40: */ + } + goto L120; + } + +/* Compute updated W. */ + + scopy_(k, &w[1], &c__1, &s[s_offset], &c__1); + +/* Initialize W(I) = Q(I,I) */ + + i__1 = *ldq + 1; + scopy_(k, &q[q_offset], &i__1, &w[1], &c__1); + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = j - 1; + for (i__ = 1; i__ <= i__2; ++i__) { + w[i__] *= q[i__ + j * q_dim1] / (dlamda[i__] - dlamda[j]); +/* L50: */ + } + i__2 = *k; + for (i__ = j + 1; i__ <= i__2; ++i__) { + w[i__] *= q[i__ + j * q_dim1] / (dlamda[i__] - dlamda[j]); +/* L60: */ + } +/* L70: */ + } + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + r__1 = sqrt(-w[i__]); + w[i__] = r_sign(&r__1, &s[i__ + s_dim1]); +/* L80: */ + } + +/* Compute eigenvectors of the modified rank-1 modification. */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = *k; + for (i__ = 1; i__ <= i__2; ++i__) { + q[i__ + j * q_dim1] = w[i__] / q[i__ + j * q_dim1]; +/* L90: */ + } + temp = snrm2_(k, &q[j * q_dim1 + 1], &c__1); + i__2 = *k; + for (i__ = 1; i__ <= i__2; ++i__) { + s[i__ + j * s_dim1] = q[i__ + j * q_dim1] / temp; +/* L100: */ + } +/* L110: */ + } + +L120: + return 0; + +/* End of SLAED9 */ + +} /* slaed9_ */ + +/* Subroutine */ int slaeda_(integer *n, integer *tlvls, integer *curlvl, + integer *curpbm, integer *prmptr, integer *perm, integer *givptr, + integer *givcol, real *givnum, real *q, integer *qptr, real *z__, + real *ztemp, integer *info) +{ + /* System generated locals */ + integer i__1, i__2, i__3; + + /* Builtin functions */ + integer pow_ii(integer *, integer *); + double sqrt(doublereal); + + /* Local variables */ + static integer i__, k, mid, ptr, curr; + extern /* Subroutine */ int srot_(integer *, real *, integer *, real *, + integer *, real *, real *); + static integer bsiz1, bsiz2, psiz1, psiz2, zptr1; + extern /* Subroutine */ int sgemv_(char *, integer *, integer *, real *, + real *, integer *, real *, integer *, real *, real *, integer *), scopy_(integer *, real *, integer *, real *, integer *), + xerbla_(char *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + September 30, 1994 + + + Purpose + ======= + + SLAEDA computes the Z vector corresponding to the merge step in the + CURLVLth step of the merge process with TLVLS steps for the CURPBMth + problem. + + Arguments + ========= + + N (input) INTEGER + The dimension of the symmetric tridiagonal matrix. N >= 0. + + TLVLS (input) INTEGER + The total number of merging levels in the overall divide and + conquer tree. + + CURLVL (input) INTEGER + The current level in the overall merge routine, + 0 <= curlvl <= tlvls. + + CURPBM (input) INTEGER + The current problem in the current level in the overall + merge routine (counting from upper left to lower right). + + PRMPTR (input) INTEGER array, dimension (N lg N) + Contains a list of pointers which indicate where in PERM a + level's permutation is stored. PRMPTR(i+1) - PRMPTR(i) + indicates the size of the permutation and incidentally the + size of the full, non-deflated problem. + + PERM (input) INTEGER array, dimension (N lg N) + Contains the permutations (from deflation and sorting) to be + applied to each eigenblock. + + GIVPTR (input) INTEGER array, dimension (N lg N) + Contains a list of pointers which indicate where in GIVCOL a + level's Givens rotations are stored. GIVPTR(i+1) - GIVPTR(i) + indicates the number of Givens rotations. + + GIVCOL (input) INTEGER array, dimension (2, N lg N) + Each pair of numbers indicates a pair of columns to take place + in a Givens rotation. + + GIVNUM (input) REAL array, dimension (2, N lg N) + Each number indicates the S value to be used in the + corresponding Givens rotation. + + Q (input) REAL array, dimension (N**2) + Contains the square eigenblocks from previous levels, the + starting positions for blocks are given by QPTR. + + QPTR (input) INTEGER array, dimension (N+2) + Contains a list of pointers which indicate where in Q an + eigenblock is stored. SQRT( QPTR(i+1) - QPTR(i) ) indicates + the size of the block. + + Z (output) REAL array, dimension (N) + On output this vector contains the updating vector (the last + row of the first sub-eigenvector matrix and the first row of + the second sub-eigenvector matrix). + + ZTEMP (workspace) REAL array, dimension (N) + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + + Further Details + =============== + + Based on contributions by + Jeff Rutter, Computer Science Division, University of California + at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --ztemp; + --z__; + --qptr; + --q; + givnum -= 3; + givcol -= 3; + --givptr; + --perm; + --prmptr; + + /* Function Body */ + *info = 0; + + if (*n < 0) { + *info = -1; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLAEDA", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + +/* Determine location of first number in second half. */ + + mid = *n / 2 + 1; + +/* Gather last/first rows of appropriate eigenblocks into center of Z */ + + ptr = 1; + +/* + Determine location of lowest level subproblem in the full storage + scheme +*/ + + i__1 = *curlvl - 1; + curr = ptr + *curpbm * pow_ii(&c__2, curlvl) + pow_ii(&c__2, &i__1) - 1; + +/* + Determine size of these matrices. We add HALF to the value of + the SQRT in case the machine underestimates one of these square + roots. +*/ + + bsiz1 = (integer) (sqrt((real) (qptr[curr + 1] - qptr[curr])) + .5f); + bsiz2 = (integer) (sqrt((real) (qptr[curr + 2] - qptr[curr + 1])) + .5f); + i__1 = mid - bsiz1 - 1; + for (k = 1; k <= i__1; ++k) { + z__[k] = 0.f; +/* L10: */ + } + scopy_(&bsiz1, &q[qptr[curr] + bsiz1 - 1], &bsiz1, &z__[mid - bsiz1], & + c__1); + scopy_(&bsiz2, &q[qptr[curr + 1]], &bsiz2, &z__[mid], &c__1); + i__1 = *n; + for (k = mid + bsiz2; k <= i__1; ++k) { + z__[k] = 0.f; +/* L20: */ + } + +/* + Loop thru remaining levels 1 -> CURLVL applying the Givens + rotations and permutation and then multiplying the center matrices + against the current Z. +*/ + + ptr = pow_ii(&c__2, tlvls) + 1; + i__1 = *curlvl - 1; + for (k = 1; k <= i__1; ++k) { + i__2 = *curlvl - k; + i__3 = *curlvl - k - 1; + curr = ptr + *curpbm * pow_ii(&c__2, &i__2) + pow_ii(&c__2, &i__3) - + 1; + psiz1 = prmptr[curr + 1] - prmptr[curr]; + psiz2 = prmptr[curr + 2] - prmptr[curr + 1]; + zptr1 = mid - psiz1; + +/* Apply Givens at CURR and CURR+1 */ + + i__2 = givptr[curr + 1] - 1; + for (i__ = givptr[curr]; i__ <= i__2; ++i__) { + srot_(&c__1, &z__[zptr1 + givcol[(i__ << 1) + 1] - 1], &c__1, & + z__[zptr1 + givcol[(i__ << 1) + 2] - 1], &c__1, &givnum[( + i__ << 1) + 1], &givnum[(i__ << 1) + 2]); +/* L30: */ + } + i__2 = givptr[curr + 2] - 1; + for (i__ = givptr[curr + 1]; i__ <= i__2; ++i__) { + srot_(&c__1, &z__[mid - 1 + givcol[(i__ << 1) + 1]], &c__1, &z__[ + mid - 1 + givcol[(i__ << 1) + 2]], &c__1, &givnum[(i__ << + 1) + 1], &givnum[(i__ << 1) + 2]); +/* L40: */ + } + psiz1 = prmptr[curr + 1] - prmptr[curr]; + psiz2 = prmptr[curr + 2] - prmptr[curr + 1]; + i__2 = psiz1 - 1; + for (i__ = 0; i__ <= i__2; ++i__) { + ztemp[i__ + 1] = z__[zptr1 + perm[prmptr[curr] + i__] - 1]; +/* L50: */ + } + i__2 = psiz2 - 1; + for (i__ = 0; i__ <= i__2; ++i__) { + ztemp[psiz1 + i__ + 1] = z__[mid + perm[prmptr[curr + 1] + i__] - + 1]; +/* L60: */ + } + +/* + Multiply Blocks at CURR and CURR+1 + + Determine size of these matrices. We add HALF to the value of + the SQRT in case the machine underestimates one of these + square roots. +*/ + + bsiz1 = (integer) (sqrt((real) (qptr[curr + 1] - qptr[curr])) + .5f); + bsiz2 = (integer) (sqrt((real) (qptr[curr + 2] - qptr[curr + 1])) + + .5f); + if (bsiz1 > 0) { + sgemv_("T", &bsiz1, &bsiz1, &c_b15, &q[qptr[curr]], &bsiz1, & + ztemp[1], &c__1, &c_b29, &z__[zptr1], &c__1); + } + i__2 = psiz1 - bsiz1; + scopy_(&i__2, &ztemp[bsiz1 + 1], &c__1, &z__[zptr1 + bsiz1], &c__1); + if (bsiz2 > 0) { + sgemv_("T", &bsiz2, &bsiz2, &c_b15, &q[qptr[curr + 1]], &bsiz2, & + ztemp[psiz1 + 1], &c__1, &c_b29, &z__[mid], &c__1); + } + i__2 = psiz2 - bsiz2; + scopy_(&i__2, &ztemp[psiz1 + bsiz2 + 1], &c__1, &z__[mid + bsiz2], & + c__1); + + i__2 = *tlvls - k; + ptr += pow_ii(&c__2, &i__2); +/* L70: */ + } + + return 0; + +/* End of SLAEDA */ + +} /* slaeda_ */ + +/* Subroutine */ int slaev2_(real *a, real *b, real *c__, real *rt1, real * + rt2, real *cs1, real *sn1) +{ + /* System generated locals */ + real r__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real ab, df, cs, ct, tb, sm, tn, rt, adf, acs; + static integer sgn1, sgn2; + static real acmn, acmx; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLAEV2 computes the eigendecomposition of a 2-by-2 symmetric matrix + [ A B ] + [ B C ]. + On return, RT1 is the eigenvalue of larger absolute value, RT2 is the + eigenvalue of smaller absolute value, and (CS1,SN1) is the unit right + eigenvector for RT1, giving the decomposition + + [ CS1 SN1 ] [ A B ] [ CS1 -SN1 ] = [ RT1 0 ] + [-SN1 CS1 ] [ B C ] [ SN1 CS1 ] [ 0 RT2 ]. + + Arguments + ========= + + A (input) REAL + The (1,1) element of the 2-by-2 matrix. + + B (input) REAL + The (1,2) element and the conjugate of the (2,1) element of + the 2-by-2 matrix. + + C (input) REAL + The (2,2) element of the 2-by-2 matrix. + + RT1 (output) REAL + The eigenvalue of larger absolute value. + + RT2 (output) REAL + The eigenvalue of smaller absolute value. + + CS1 (output) REAL + SN1 (output) REAL + The vector (CS1, SN1) is a unit right eigenvector for RT1. + + Further Details + =============== + + RT1 is accurate to a few ulps barring over/underflow. + + RT2 may be inaccurate if there is massive cancellation in the + determinant A*C-B*B; higher precision or correctly rounded or + correctly truncated arithmetic would be needed to compute RT2 + accurately in all cases. + + CS1 and SN1 are accurate to a few ulps barring over/underflow. + + Overflow is possible only if RT1 is within a factor of 5 of overflow. + Underflow is harmless if the input data is 0 or exceeds + underflow_threshold / macheps. + + ===================================================================== + + + Compute the eigenvalues +*/ + + sm = *a + *c__; + df = *a - *c__; + adf = dabs(df); + tb = *b + *b; + ab = dabs(tb); + if (dabs(*a) > dabs(*c__)) { + acmx = *a; + acmn = *c__; + } else { + acmx = *c__; + acmn = *a; + } + if (adf > ab) { +/* Computing 2nd power */ + r__1 = ab / adf; + rt = adf * sqrt(r__1 * r__1 + 1.f); + } else if (adf < ab) { +/* Computing 2nd power */ + r__1 = adf / ab; + rt = ab * sqrt(r__1 * r__1 + 1.f); + } else { + +/* Includes case AB=ADF=0 */ + + rt = ab * sqrt(2.f); + } + if (sm < 0.f) { + *rt1 = (sm - rt) * .5f; + sgn1 = -1; + +/* + Order of execution important. + To get fully accurate smaller eigenvalue, + next line needs to be executed in higher precision. +*/ + + *rt2 = acmx / *rt1 * acmn - *b / *rt1 * *b; + } else if (sm > 0.f) { + *rt1 = (sm + rt) * .5f; + sgn1 = 1; + +/* + Order of execution important. + To get fully accurate smaller eigenvalue, + next line needs to be executed in higher precision. +*/ + + *rt2 = acmx / *rt1 * acmn - *b / *rt1 * *b; + } else { + +/* Includes case RT1 = RT2 = 0 */ + + *rt1 = rt * .5f; + *rt2 = rt * -.5f; + sgn1 = 1; + } + +/* Compute the eigenvector */ + + if (df >= 0.f) { + cs = df + rt; + sgn2 = 1; + } else { + cs = df - rt; + sgn2 = -1; + } + acs = dabs(cs); + if (acs > ab) { + ct = -tb / cs; + *sn1 = 1.f / sqrt(ct * ct + 1.f); + *cs1 = ct * *sn1; + } else { + if (ab == 0.f) { + *cs1 = 1.f; + *sn1 = 0.f; + } else { + tn = -cs / tb; + *cs1 = 1.f / sqrt(tn * tn + 1.f); + *sn1 = tn * *cs1; + } + } + if (sgn1 == sgn2) { + tn = *cs1; + *cs1 = -(*sn1); + *sn1 = tn; + } + return 0; + +/* End of SLAEV2 */ + +} /* slaev2_ */ + +/* Subroutine */ int slahqr_(logical *wantt, logical *wantz, integer *n, + integer *ilo, integer *ihi, real *h__, integer *ldh, real *wr, real * + wi, integer *iloz, integer *ihiz, real *z__, integer *ldz, integer * + info) +{ + /* System generated locals */ + integer h_dim1, h_offset, z_dim1, z_offset, i__1, i__2, i__3, i__4; + real r__1, r__2; + + /* Builtin functions */ + double sqrt(doublereal), r_sign(real *, real *); + + /* Local variables */ + static integer i__, j, k, l, m; + static real s, v[3]; + static integer i1, i2; + static real t1, t2, t3, v1, v2, v3, h00, h10, h11, h12, h21, h22, h33, + h44; + static integer nh; + static real cs; + static integer nr; + static real sn; + static integer nz; + static real ave, h33s, h44s; + static integer itn, its; + static real ulp, sum, tst1, h43h34, disc, unfl, ovfl, work[1]; + extern /* Subroutine */ int srot_(integer *, real *, integer *, real *, + integer *, real *, real *), scopy_(integer *, real *, integer *, + real *, integer *), slanv2_(real *, real *, real *, real *, real * + , real *, real *, real *, real *, real *), slabad_(real *, real *) + ; + extern doublereal slamch_(char *); + extern /* Subroutine */ int slarfg_(integer *, real *, real *, integer *, + real *); + extern doublereal slanhs_(char *, integer *, real *, integer *, real *); + static real smlnum; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SLAHQR is an auxiliary routine called by SHSEQR to update the + eigenvalues and Schur decomposition already computed by SHSEQR, by + dealing with the Hessenberg submatrix in rows and columns ILO to IHI. + + Arguments + ========= + + WANTT (input) LOGICAL + = .TRUE. : the full Schur form T is required; + = .FALSE.: only eigenvalues are required. + + WANTZ (input) LOGICAL + = .TRUE. : the matrix of Schur vectors Z is required; + = .FALSE.: Schur vectors are not required. + + N (input) INTEGER + The order of the matrix H. N >= 0. + + ILO (input) INTEGER + IHI (input) INTEGER + It is assumed that H is already upper quasi-triangular in + rows and columns IHI+1:N, and that H(ILO,ILO-1) = 0 (unless + ILO = 1). SLAHQR works primarily with the Hessenberg + submatrix in rows and columns ILO to IHI, but applies + transformations to all of H if WANTT is .TRUE.. + 1 <= ILO <= max(1,IHI); IHI <= N. + + H (input/output) REAL array, dimension (LDH,N) + On entry, the upper Hessenberg matrix H. + On exit, if WANTT is .TRUE., H is upper quasi-triangular in + rows and columns ILO:IHI, with any 2-by-2 diagonal blocks in + standard form. If WANTT is .FALSE., the contents of H are + unspecified on exit. + + LDH (input) INTEGER + The leading dimension of the array H. LDH >= max(1,N). + + WR (output) REAL array, dimension (N) + WI (output) REAL array, dimension (N) + The real and imaginary parts, respectively, of the computed + eigenvalues ILO to IHI are stored in the corresponding + elements of WR and WI. If two eigenvalues are computed as a + complex conjugate pair, they are stored in consecutive + elements of WR and WI, say the i-th and (i+1)th, with + WI(i) > 0 and WI(i+1) < 0. If WANTT is .TRUE., the + eigenvalues are stored in the same order as on the diagonal + of the Schur form returned in H, with WR(i) = H(i,i), and, if + H(i:i+1,i:i+1) is a 2-by-2 diagonal block, + WI(i) = sqrt(H(i+1,i)*H(i,i+1)) and WI(i+1) = -WI(i). + + ILOZ (input) INTEGER + IHIZ (input) INTEGER + Specify the rows of Z to which transformations must be + applied if WANTZ is .TRUE.. + 1 <= ILOZ <= ILO; IHI <= IHIZ <= N. + + Z (input/output) REAL array, dimension (LDZ,N) + If WANTZ is .TRUE., on entry Z must contain the current + matrix Z of transformations accumulated by SHSEQR, and on + exit Z has been updated; transformations are applied only to + the submatrix Z(ILOZ:IHIZ,ILO:IHI). + If WANTZ is .FALSE., Z is not referenced. + + LDZ (input) INTEGER + The leading dimension of the array Z. LDZ >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + > 0: SLAHQR failed to compute all the eigenvalues ILO to IHI + in a total of 30*(IHI-ILO+1) iterations; if INFO = i, + elements i+1:ihi of WR and WI contain those eigenvalues + which have been successfully computed. + + Further Details + =============== + + 2-96 Based on modifications by + David Day, Sandia National Laboratory, USA + + ===================================================================== +*/ + + + /* Parameter adjustments */ + h_dim1 = *ldh; + h_offset = 1 + h_dim1; + h__ -= h_offset; + --wr; + --wi; + z_dim1 = *ldz; + z_offset = 1 + z_dim1; + z__ -= z_offset; + + /* Function Body */ + *info = 0; + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + if (*ilo == *ihi) { + wr[*ilo] = h__[*ilo + *ilo * h_dim1]; + wi[*ilo] = 0.f; + return 0; + } + + nh = *ihi - *ilo + 1; + nz = *ihiz - *iloz + 1; + +/* + Set machine-dependent constants for the stopping criterion. + If norm(H) <= sqrt(OVFL), overflow should not occur. +*/ + + unfl = slamch_("Safe minimum"); + ovfl = 1.f / unfl; + slabad_(&unfl, &ovfl); + ulp = slamch_("Precision"); + smlnum = unfl * (nh / ulp); + +/* + I1 and I2 are the indices of the first row and last column of H + to which transformations must be applied. If eigenvalues only are + being computed, I1 and I2 are set inside the main loop. +*/ + + if (*wantt) { + i1 = 1; + i2 = *n; + } + +/* ITN is the total number of QR iterations allowed. */ + + itn = nh * 30; + +/* + The main loop begins here. I is the loop index and decreases from + IHI to ILO in steps of 1 or 2. Each iteration of the loop works + with the active submatrix in rows and columns L to I. + Eigenvalues I+1 to IHI have already converged. Either L = ILO or + H(L,L-1) is negligible so that the matrix splits. +*/ + + i__ = *ihi; +L10: + l = *ilo; + if (i__ < *ilo) { + goto L150; + } + +/* + Perform QR iterations on rows and columns ILO to I until a + submatrix of order 1 or 2 splits off at the bottom because a + subdiagonal element has become negligible. +*/ + + i__1 = itn; + for (its = 0; its <= i__1; ++its) { + +/* Look for a single small subdiagonal element. */ + + i__2 = l + 1; + for (k = i__; k >= i__2; --k) { + tst1 = (r__1 = h__[k - 1 + (k - 1) * h_dim1], dabs(r__1)) + (r__2 + = h__[k + k * h_dim1], dabs(r__2)); + if (tst1 == 0.f) { + i__3 = i__ - l + 1; + tst1 = slanhs_("1", &i__3, &h__[l + l * h_dim1], ldh, work); + } +/* Computing MAX */ + r__2 = ulp * tst1; + if ((r__1 = h__[k + (k - 1) * h_dim1], dabs(r__1)) <= dmax(r__2, + smlnum)) { + goto L30; + } +/* L20: */ + } +L30: + l = k; + if (l > *ilo) { + +/* H(L,L-1) is negligible */ + + h__[l + (l - 1) * h_dim1] = 0.f; + } + +/* Exit from loop if a submatrix of order 1 or 2 has split off. */ + + if (l >= i__ - 1) { + goto L140; + } + +/* + Now the active submatrix is in rows and columns L to I. If + eigenvalues only are being computed, only the active submatrix + need be transformed. +*/ + + if (! (*wantt)) { + i1 = l; + i2 = i__; + } + + if (its == 10 || its == 20) { + +/* Exceptional shift. */ + + s = (r__1 = h__[i__ + (i__ - 1) * h_dim1], dabs(r__1)) + (r__2 = + h__[i__ - 1 + (i__ - 2) * h_dim1], dabs(r__2)); + h44 = s * .75f + h__[i__ + i__ * h_dim1]; + h33 = h44; + h43h34 = s * -.4375f * s; + } else { + +/* + Prepare to use Francis' double shift + (i.e. 2nd degree generalized Rayleigh quotient) +*/ + + h44 = h__[i__ + i__ * h_dim1]; + h33 = h__[i__ - 1 + (i__ - 1) * h_dim1]; + h43h34 = h__[i__ + (i__ - 1) * h_dim1] * h__[i__ - 1 + i__ * + h_dim1]; + s = h__[i__ - 1 + (i__ - 2) * h_dim1] * h__[i__ - 1 + (i__ - 2) * + h_dim1]; + disc = (h33 - h44) * .5f; + disc = disc * disc + h43h34; + if (disc > 0.f) { + +/* Real roots: use Wilkinson's shift twice */ + + disc = sqrt(disc); + ave = (h33 + h44) * .5f; + if (dabs(h33) - dabs(h44) > 0.f) { + h33 = h33 * h44 - h43h34; + h44 = h33 / (r_sign(&disc, &ave) + ave); + } else { + h44 = r_sign(&disc, &ave) + ave; + } + h33 = h44; + h43h34 = 0.f; + } + } + +/* Look for two consecutive small subdiagonal elements. */ + + i__2 = l; + for (m = i__ - 2; m >= i__2; --m) { +/* + Determine the effect of starting the double-shift QR + iteration at row M, and see if this would make H(M,M-1) + negligible. +*/ + + h11 = h__[m + m * h_dim1]; + h22 = h__[m + 1 + (m + 1) * h_dim1]; + h21 = h__[m + 1 + m * h_dim1]; + h12 = h__[m + (m + 1) * h_dim1]; + h44s = h44 - h11; + h33s = h33 - h11; + v1 = (h33s * h44s - h43h34) / h21 + h12; + v2 = h22 - h11 - h33s - h44s; + v3 = h__[m + 2 + (m + 1) * h_dim1]; + s = dabs(v1) + dabs(v2) + dabs(v3); + v1 /= s; + v2 /= s; + v3 /= s; + v[0] = v1; + v[1] = v2; + v[2] = v3; + if (m == l) { + goto L50; + } + h00 = h__[m - 1 + (m - 1) * h_dim1]; + h10 = h__[m + (m - 1) * h_dim1]; + tst1 = dabs(v1) * (dabs(h00) + dabs(h11) + dabs(h22)); + if (dabs(h10) * (dabs(v2) + dabs(v3)) <= ulp * tst1) { + goto L50; + } +/* L40: */ + } +L50: + +/* Double-shift QR step */ + + i__2 = i__ - 1; + for (k = m; k <= i__2; ++k) { + +/* + The first iteration of this loop determines a reflection G + from the vector V and applies it from left and right to H, + thus creating a nonzero bulge below the subdiagonal. + + Each subsequent iteration determines a reflection G to + restore the Hessenberg form in the (K-1)th column, and thus + chases the bulge one step toward the bottom of the active + submatrix. NR is the order of G. + + Computing MIN +*/ + i__3 = 3, i__4 = i__ - k + 1; + nr = min(i__3,i__4); + if (k > m) { + scopy_(&nr, &h__[k + (k - 1) * h_dim1], &c__1, v, &c__1); + } + slarfg_(&nr, v, &v[1], &c__1, &t1); + if (k > m) { + h__[k + (k - 1) * h_dim1] = v[0]; + h__[k + 1 + (k - 1) * h_dim1] = 0.f; + if (k < i__ - 1) { + h__[k + 2 + (k - 1) * h_dim1] = 0.f; + } + } else if (m > l) { + h__[k + (k - 1) * h_dim1] = -h__[k + (k - 1) * h_dim1]; + } + v2 = v[1]; + t2 = t1 * v2; + if (nr == 3) { + v3 = v[2]; + t3 = t1 * v3; + +/* + Apply G from the left to transform the rows of the matrix + in columns K to I2. +*/ + + i__3 = i2; + for (j = k; j <= i__3; ++j) { + sum = h__[k + j * h_dim1] + v2 * h__[k + 1 + j * h_dim1] + + v3 * h__[k + 2 + j * h_dim1]; + h__[k + j * h_dim1] -= sum * t1; + h__[k + 1 + j * h_dim1] -= sum * t2; + h__[k + 2 + j * h_dim1] -= sum * t3; +/* L60: */ + } + +/* + Apply G from the right to transform the columns of the + matrix in rows I1 to min(K+3,I). + + Computing MIN +*/ + i__4 = k + 3; + i__3 = min(i__4,i__); + for (j = i1; j <= i__3; ++j) { + sum = h__[j + k * h_dim1] + v2 * h__[j + (k + 1) * h_dim1] + + v3 * h__[j + (k + 2) * h_dim1]; + h__[j + k * h_dim1] -= sum * t1; + h__[j + (k + 1) * h_dim1] -= sum * t2; + h__[j + (k + 2) * h_dim1] -= sum * t3; +/* L70: */ + } + + if (*wantz) { + +/* Accumulate transformations in the matrix Z */ + + i__3 = *ihiz; + for (j = *iloz; j <= i__3; ++j) { + sum = z__[j + k * z_dim1] + v2 * z__[j + (k + 1) * + z_dim1] + v3 * z__[j + (k + 2) * z_dim1]; + z__[j + k * z_dim1] -= sum * t1; + z__[j + (k + 1) * z_dim1] -= sum * t2; + z__[j + (k + 2) * z_dim1] -= sum * t3; +/* L80: */ + } + } + } else if (nr == 2) { + +/* + Apply G from the left to transform the rows of the matrix + in columns K to I2. +*/ + + i__3 = i2; + for (j = k; j <= i__3; ++j) { + sum = h__[k + j * h_dim1] + v2 * h__[k + 1 + j * h_dim1]; + h__[k + j * h_dim1] -= sum * t1; + h__[k + 1 + j * h_dim1] -= sum * t2; +/* L90: */ + } + +/* + Apply G from the right to transform the columns of the + matrix in rows I1 to min(K+3,I). +*/ + + i__3 = i__; + for (j = i1; j <= i__3; ++j) { + sum = h__[j + k * h_dim1] + v2 * h__[j + (k + 1) * h_dim1] + ; + h__[j + k * h_dim1] -= sum * t1; + h__[j + (k + 1) * h_dim1] -= sum * t2; +/* L100: */ + } + + if (*wantz) { + +/* Accumulate transformations in the matrix Z */ + + i__3 = *ihiz; + for (j = *iloz; j <= i__3; ++j) { + sum = z__[j + k * z_dim1] + v2 * z__[j + (k + 1) * + z_dim1]; + z__[j + k * z_dim1] -= sum * t1; + z__[j + (k + 1) * z_dim1] -= sum * t2; +/* L110: */ + } + } + } +/* L120: */ + } + +/* L130: */ + } + +/* Failure to converge in remaining number of iterations */ + + *info = i__; + return 0; + +L140: + + if (l == i__) { + +/* H(I,I-1) is negligible: one eigenvalue has converged. */ + + wr[i__] = h__[i__ + i__ * h_dim1]; + wi[i__] = 0.f; + } else if (l == i__ - 1) { + +/* + H(I-1,I-2) is negligible: a pair of eigenvalues have converged. + + Transform the 2-by-2 submatrix to standard Schur form, + and compute and store the eigenvalues. +*/ + + slanv2_(&h__[i__ - 1 + (i__ - 1) * h_dim1], &h__[i__ - 1 + i__ * + h_dim1], &h__[i__ + (i__ - 1) * h_dim1], &h__[i__ + i__ * + h_dim1], &wr[i__ - 1], &wi[i__ - 1], &wr[i__], &wi[i__], &cs, + &sn); + + if (*wantt) { + +/* Apply the transformation to the rest of H. */ + + if (i2 > i__) { + i__1 = i2 - i__; + srot_(&i__1, &h__[i__ - 1 + (i__ + 1) * h_dim1], ldh, &h__[ + i__ + (i__ + 1) * h_dim1], ldh, &cs, &sn); + } + i__1 = i__ - i1 - 1; + srot_(&i__1, &h__[i1 + (i__ - 1) * h_dim1], &c__1, &h__[i1 + i__ * + h_dim1], &c__1, &cs, &sn); + } + if (*wantz) { + +/* Apply the transformation to Z. */ + + srot_(&nz, &z__[*iloz + (i__ - 1) * z_dim1], &c__1, &z__[*iloz + + i__ * z_dim1], &c__1, &cs, &sn); + } + } + +/* + Decrement number of remaining iterations, and return to start of + the main loop with new value of I. +*/ + + itn -= its; + i__ = l - 1; + goto L10; + +L150: + return 0; + +/* End of SLAHQR */ + +} /* slahqr_ */ + +/* Subroutine */ int slahrd_(integer *n, integer *k, integer *nb, real *a, + integer *lda, real *tau, real *t, integer *ldt, real *y, integer *ldy) +{ + /* System generated locals */ + integer a_dim1, a_offset, t_dim1, t_offset, y_dim1, y_offset, i__1, i__2, + i__3; + real r__1; + + /* Local variables */ + static integer i__; + static real ei; + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *), + sgemv_(char *, integer *, integer *, real *, real *, integer *, + real *, integer *, real *, real *, integer *), scopy_( + integer *, real *, integer *, real *, integer *), saxpy_(integer * + , real *, real *, integer *, real *, integer *), strmv_(char *, + char *, char *, integer *, real *, integer *, real *, integer *), slarfg_(integer *, real *, real *, + integer *, real *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SLAHRD reduces the first NB columns of a real general n-by-(n-k+1) + matrix A so that elements below the k-th subdiagonal are zero. The + reduction is performed by an orthogonal similarity transformation + Q' * A * Q. The routine returns the matrices V and T which determine + Q as a block reflector I - V*T*V', and also the matrix Y = A * V * T. + + This is an auxiliary routine called by SGEHRD. + + Arguments + ========= + + N (input) INTEGER + The order of the matrix A. + + K (input) INTEGER + The offset for the reduction. Elements below the k-th + subdiagonal in the first NB columns are reduced to zero. + + NB (input) INTEGER + The number of columns to be reduced. + + A (input/output) REAL array, dimension (LDA,N-K+1) + On entry, the n-by-(n-k+1) general matrix A. + On exit, the elements on and above the k-th subdiagonal in + the first NB columns are overwritten with the corresponding + elements of the reduced matrix; the elements below the k-th + subdiagonal, with the array TAU, represent the matrix Q as a + product of elementary reflectors. The other columns of A are + unchanged. See Further Details. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + TAU (output) REAL array, dimension (NB) + The scalar factors of the elementary reflectors. See Further + Details. + + T (output) REAL array, dimension (LDT,NB) + The upper triangular matrix T. + + LDT (input) INTEGER + The leading dimension of the array T. LDT >= NB. + + Y (output) REAL array, dimension (LDY,NB) + The n-by-nb matrix Y. + + LDY (input) INTEGER + The leading dimension of the array Y. LDY >= N. + + Further Details + =============== + + The matrix Q is represented as a product of nb elementary reflectors + + Q = H(1) H(2) . . . H(nb). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(1:i+k-1) = 0, v(i+k) = 1; v(i+k+1:n) is stored on exit in + A(i+k+1:n,i), and tau in TAU(i). + + The elements of the vectors v together form the (n-k+1)-by-nb matrix + V which is needed, with T and Y, to apply the transformation to the + unreduced part of the matrix, using an update of the form: + A := (I - V*T*V') * (A - Y*V'). + + The contents of A on exit are illustrated by the following example + with n = 7, k = 3 and nb = 2: + + ( a h a a a ) + ( a h a a a ) + ( a h a a a ) + ( h h a a a ) + ( v1 h a a a ) + ( v1 v2 a a a ) + ( v1 v2 a a a ) + + where a denotes an element of the original matrix A, h denotes a + modified element of the upper Hessenberg matrix H, and vi denotes an + element of the vector defining H(i). + + ===================================================================== + + + Quick return if possible +*/ + + /* Parameter adjustments */ + --tau; + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + t_dim1 = *ldt; + t_offset = 1 + t_dim1; + t -= t_offset; + y_dim1 = *ldy; + y_offset = 1 + y_dim1; + y -= y_offset; + + /* Function Body */ + if (*n <= 1) { + return 0; + } + + i__1 = *nb; + for (i__ = 1; i__ <= i__1; ++i__) { + if (i__ > 1) { + +/* + Update A(1:n,i) + + Compute i-th column of A - Y * V' +*/ + + i__2 = i__ - 1; + sgemv_("No transpose", n, &i__2, &c_b151, &y[y_offset], ldy, &a[* + k + i__ - 1 + a_dim1], lda, &c_b15, &a[i__ * a_dim1 + 1], + &c__1); + +/* + Apply I - V * T' * V' to this column (call it b) from the + left, using the last column of T as workspace + + Let V = ( V1 ) and b = ( b1 ) (first I-1 rows) + ( V2 ) ( b2 ) + + where V1 is unit lower triangular + + w := V1' * b1 +*/ + + i__2 = i__ - 1; + scopy_(&i__2, &a[*k + 1 + i__ * a_dim1], &c__1, &t[*nb * t_dim1 + + 1], &c__1); + i__2 = i__ - 1; + strmv_("Lower", "Transpose", "Unit", &i__2, &a[*k + 1 + a_dim1], + lda, &t[*nb * t_dim1 + 1], &c__1); + +/* w := w + V2'*b2 */ + + i__2 = *n - *k - i__ + 1; + i__3 = i__ - 1; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &a[*k + i__ + a_dim1], + lda, &a[*k + i__ + i__ * a_dim1], &c__1, &c_b15, &t[*nb * + t_dim1 + 1], &c__1); + +/* w := T'*w */ + + i__2 = i__ - 1; + strmv_("Upper", "Transpose", "Non-unit", &i__2, &t[t_offset], ldt, + &t[*nb * t_dim1 + 1], &c__1); + +/* b2 := b2 - V2*w */ + + i__2 = *n - *k - i__ + 1; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &a[*k + i__ + + a_dim1], lda, &t[*nb * t_dim1 + 1], &c__1, &c_b15, &a[*k + + i__ + i__ * a_dim1], &c__1); + +/* b1 := b1 - V1*w */ + + i__2 = i__ - 1; + strmv_("Lower", "No transpose", "Unit", &i__2, &a[*k + 1 + a_dim1] + , lda, &t[*nb * t_dim1 + 1], &c__1); + i__2 = i__ - 1; + saxpy_(&i__2, &c_b151, &t[*nb * t_dim1 + 1], &c__1, &a[*k + 1 + + i__ * a_dim1], &c__1); + + a[*k + i__ - 1 + (i__ - 1) * a_dim1] = ei; + } + +/* + Generate the elementary reflector H(i) to annihilate + A(k+i+1:n,i) +*/ + + i__2 = *n - *k - i__ + 1; +/* Computing MIN */ + i__3 = *k + i__ + 1; + slarfg_(&i__2, &a[*k + i__ + i__ * a_dim1], &a[min(i__3,*n) + i__ * + a_dim1], &c__1, &tau[i__]); + ei = a[*k + i__ + i__ * a_dim1]; + a[*k + i__ + i__ * a_dim1] = 1.f; + +/* Compute Y(1:n,i) */ + + i__2 = *n - *k - i__ + 1; + sgemv_("No transpose", n, &i__2, &c_b15, &a[(i__ + 1) * a_dim1 + 1], + lda, &a[*k + i__ + i__ * a_dim1], &c__1, &c_b29, &y[i__ * + y_dim1 + 1], &c__1); + i__2 = *n - *k - i__ + 1; + i__3 = i__ - 1; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &a[*k + i__ + a_dim1], lda, + &a[*k + i__ + i__ * a_dim1], &c__1, &c_b29, &t[i__ * t_dim1 + + 1], &c__1); + i__2 = i__ - 1; + sgemv_("No transpose", n, &i__2, &c_b151, &y[y_offset], ldy, &t[i__ * + t_dim1 + 1], &c__1, &c_b15, &y[i__ * y_dim1 + 1], &c__1); + sscal_(n, &tau[i__], &y[i__ * y_dim1 + 1], &c__1); + +/* Compute T(1:i,i) */ + + i__2 = i__ - 1; + r__1 = -tau[i__]; + sscal_(&i__2, &r__1, &t[i__ * t_dim1 + 1], &c__1); + i__2 = i__ - 1; + strmv_("Upper", "No transpose", "Non-unit", &i__2, &t[t_offset], ldt, + &t[i__ * t_dim1 + 1], &c__1) + ; + t[i__ + i__ * t_dim1] = tau[i__]; + +/* L10: */ + } + a[*k + *nb + *nb * a_dim1] = ei; + + return 0; + +/* End of SLAHRD */ + +} /* slahrd_ */ + +/* Subroutine */ int slaln2_(logical *ltrans, integer *na, integer *nw, real * + smin, real *ca, real *a, integer *lda, real *d1, real *d2, real *b, + integer *ldb, real *wr, real *wi, real *x, integer *ldx, real *scale, + real *xnorm, integer *info) +{ + /* Initialized data */ + + static logical cswap[4] = { FALSE_,FALSE_,TRUE_,TRUE_ }; + static logical rswap[4] = { FALSE_,TRUE_,FALSE_,TRUE_ }; + static integer ipivot[16] /* was [4][4] */ = { 1,2,3,4,2,1,4,3,3,4,1,2, + 4,3,2,1 }; + + /* System generated locals */ + integer a_dim1, a_offset, b_dim1, b_offset, x_dim1, x_offset; + real r__1, r__2, r__3, r__4, r__5, r__6; + static real equiv_0[4], equiv_1[4]; + + /* Local variables */ + static integer j; +#define ci (equiv_0) +#define cr (equiv_1) + static real bi1, bi2, br1, br2, xi1, xi2, xr1, xr2, ci21, ci22, cr21, + cr22, li21, csi, ui11, lr21, ui12, ui22; +#define civ (equiv_0) + static real csr, ur11, ur12, ur22; +#define crv (equiv_1) + static real bbnd, cmax, ui11r, ui12s, temp, ur11r, ur12s, u22abs; + static integer icmax; + static real bnorm, cnorm, smini; + extern doublereal slamch_(char *); + static real bignum; + extern /* Subroutine */ int sladiv_(real *, real *, real *, real *, real * + , real *); + static real smlnum; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLALN2 solves a system of the form (ca A - w D ) X = s B + or (ca A' - w D) X = s B with possible scaling ("s") and + perturbation of A. (A' means A-transpose.) + + A is an NA x NA real matrix, ca is a real scalar, D is an NA x NA + real diagonal matrix, w is a real or complex value, and X and B are + NA x 1 matrices -- real if w is real, complex if w is complex. NA + may be 1 or 2. + + If w is complex, X and B are represented as NA x 2 matrices, + the first column of each being the real part and the second + being the imaginary part. + + "s" is a scaling factor (.LE. 1), computed by SLALN2, which is + so chosen that X can be computed without overflow. X is further + scaled if necessary to assure that norm(ca A - w D)*norm(X) is less + than overflow. + + If both singular values of (ca A - w D) are less than SMIN, + SMIN*identity will be used instead of (ca A - w D). If only one + singular value is less than SMIN, one element of (ca A - w D) will be + perturbed enough to make the smallest singular value roughly SMIN. + If both singular values are at least SMIN, (ca A - w D) will not be + perturbed. In any case, the perturbation will be at most some small + multiple of max( SMIN, ulp*norm(ca A - w D) ). The singular values + are computed by infinity-norm approximations, and thus will only be + correct to a factor of 2 or so. + + Note: all input quantities are assumed to be smaller than overflow + by a reasonable factor. (See BIGNUM.) + + Arguments + ========== + + LTRANS (input) LOGICAL + =.TRUE.: A-transpose will be used. + =.FALSE.: A will be used (not transposed.) + + NA (input) INTEGER + The size of the matrix A. It may (only) be 1 or 2. + + NW (input) INTEGER + 1 if "w" is real, 2 if "w" is complex. It may only be 1 + or 2. + + SMIN (input) REAL + The desired lower bound on the singular values of A. This + should be a safe distance away from underflow or overflow, + say, between (underflow/machine precision) and (machine + precision * overflow ). (See BIGNUM and ULP.) + + CA (input) REAL + The coefficient c, which A is multiplied by. + + A (input) REAL array, dimension (LDA,NA) + The NA x NA matrix A. + + LDA (input) INTEGER + The leading dimension of A. It must be at least NA. + + D1 (input) REAL + The 1,1 element in the diagonal matrix D. + + D2 (input) REAL + The 2,2 element in the diagonal matrix D. Not used if NW=1. + + B (input) REAL array, dimension (LDB,NW) + The NA x NW matrix B (right-hand side). If NW=2 ("w" is + complex), column 1 contains the real part of B and column 2 + contains the imaginary part. + + LDB (input) INTEGER + The leading dimension of B. It must be at least NA. + + WR (input) REAL + The real part of the scalar "w". + + WI (input) REAL + The imaginary part of the scalar "w". Not used if NW=1. + + X (output) REAL array, dimension (LDX,NW) + The NA x NW matrix X (unknowns), as computed by SLALN2. + If NW=2 ("w" is complex), on exit, column 1 will contain + the real part of X and column 2 will contain the imaginary + part. + + LDX (input) INTEGER + The leading dimension of X. It must be at least NA. + + SCALE (output) REAL + The scale factor that B must be multiplied by to insure + that overflow does not occur when computing X. Thus, + (ca A - w D) X will be SCALE*B, not B (ignoring + perturbations of A.) It will be at most 1. + + XNORM (output) REAL + The infinity-norm of X, when X is regarded as an NA x NW + real matrix. + + INFO (output) INTEGER + An error flag. It will be set to zero if no error occurs, + a negative number if an argument is in error, or a positive + number if ca A - w D had to be perturbed. + The possible values are: + = 0: No error occurred, and (ca A - w D) did not have to be + perturbed. + = 1: (ca A - w D) had to be perturbed to make its smallest + (or only) singular value greater than SMIN. + NOTE: In the interests of speed, this routine does not + check the inputs for errors. + + ===================================================================== +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + b_dim1 = *ldb; + b_offset = 1 + b_dim1; + b -= b_offset; + x_dim1 = *ldx; + x_offset = 1 + x_dim1; + x -= x_offset; + + /* Function Body */ + +/* Compute BIGNUM */ + + smlnum = 2.f * slamch_("Safe minimum"); + bignum = 1.f / smlnum; + smini = dmax(*smin,smlnum); + +/* Don't check for input errors */ + + *info = 0; + +/* Standard Initializations */ + + *scale = 1.f; + + if (*na == 1) { + +/* 1 x 1 (i.e., scalar) system C X = B */ + + if (*nw == 1) { + +/* + Real 1x1 system. + + C = ca A - w D +*/ + + csr = *ca * a[a_dim1 + 1] - *wr * *d1; + cnorm = dabs(csr); + +/* If | C | < SMINI, use C = SMINI */ + + if (cnorm < smini) { + csr = smini; + cnorm = smini; + *info = 1; + } + +/* Check scaling for X = B / C */ + + bnorm = (r__1 = b[b_dim1 + 1], dabs(r__1)); + if (cnorm < 1.f && bnorm > 1.f) { + if (bnorm > bignum * cnorm) { + *scale = 1.f / bnorm; + } + } + +/* Compute X */ + + x[x_dim1 + 1] = b[b_dim1 + 1] * *scale / csr; + *xnorm = (r__1 = x[x_dim1 + 1], dabs(r__1)); + } else { + +/* + Complex 1x1 system (w is complex) + + C = ca A - w D +*/ + + csr = *ca * a[a_dim1 + 1] - *wr * *d1; + csi = -(*wi) * *d1; + cnorm = dabs(csr) + dabs(csi); + +/* If | C | < SMINI, use C = SMINI */ + + if (cnorm < smini) { + csr = smini; + csi = 0.f; + cnorm = smini; + *info = 1; + } + +/* Check scaling for X = B / C */ + + bnorm = (r__1 = b[b_dim1 + 1], dabs(r__1)) + (r__2 = b[(b_dim1 << + 1) + 1], dabs(r__2)); + if (cnorm < 1.f && bnorm > 1.f) { + if (bnorm > bignum * cnorm) { + *scale = 1.f / bnorm; + } + } + +/* Compute X */ + + r__1 = *scale * b[b_dim1 + 1]; + r__2 = *scale * b[(b_dim1 << 1) + 1]; + sladiv_(&r__1, &r__2, &csr, &csi, &x[x_dim1 + 1], &x[(x_dim1 << 1) + + 1]); + *xnorm = (r__1 = x[x_dim1 + 1], dabs(r__1)) + (r__2 = x[(x_dim1 << + 1) + 1], dabs(r__2)); + } + + } else { + +/* + 2x2 System + + Compute the real part of C = ca A - w D (or ca A' - w D ) +*/ + + cr[0] = *ca * a[a_dim1 + 1] - *wr * *d1; + cr[3] = *ca * a[(a_dim1 << 1) + 2] - *wr * *d2; + if (*ltrans) { + cr[2] = *ca * a[a_dim1 + 2]; + cr[1] = *ca * a[(a_dim1 << 1) + 1]; + } else { + cr[1] = *ca * a[a_dim1 + 2]; + cr[2] = *ca * a[(a_dim1 << 1) + 1]; + } + + if (*nw == 1) { + +/* + Real 2x2 system (w is real) + + Find the largest element in C +*/ + + cmax = 0.f; + icmax = 0; + + for (j = 1; j <= 4; ++j) { + if ((r__1 = crv[j - 1], dabs(r__1)) > cmax) { + cmax = (r__1 = crv[j - 1], dabs(r__1)); + icmax = j; + } +/* L10: */ + } + +/* If norm(C) < SMINI, use SMINI*identity. */ + + if (cmax < smini) { +/* Computing MAX */ + r__3 = (r__1 = b[b_dim1 + 1], dabs(r__1)), r__4 = (r__2 = b[ + b_dim1 + 2], dabs(r__2)); + bnorm = dmax(r__3,r__4); + if (smini < 1.f && bnorm > 1.f) { + if (bnorm > bignum * smini) { + *scale = 1.f / bnorm; + } + } + temp = *scale / smini; + x[x_dim1 + 1] = temp * b[b_dim1 + 1]; + x[x_dim1 + 2] = temp * b[b_dim1 + 2]; + *xnorm = temp * bnorm; + *info = 1; + return 0; + } + +/* Gaussian elimination with complete pivoting. */ + + ur11 = crv[icmax - 1]; + cr21 = crv[ipivot[(icmax << 2) - 3] - 1]; + ur12 = crv[ipivot[(icmax << 2) - 2] - 1]; + cr22 = crv[ipivot[(icmax << 2) - 1] - 1]; + ur11r = 1.f / ur11; + lr21 = ur11r * cr21; + ur22 = cr22 - ur12 * lr21; + +/* If smaller pivot < SMINI, use SMINI */ + + if (dabs(ur22) < smini) { + ur22 = smini; + *info = 1; + } + if (rswap[icmax - 1]) { + br1 = b[b_dim1 + 2]; + br2 = b[b_dim1 + 1]; + } else { + br1 = b[b_dim1 + 1]; + br2 = b[b_dim1 + 2]; + } + br2 -= lr21 * br1; +/* Computing MAX */ + r__2 = (r__1 = br1 * (ur22 * ur11r), dabs(r__1)), r__3 = dabs(br2) + ; + bbnd = dmax(r__2,r__3); + if (bbnd > 1.f && dabs(ur22) < 1.f) { + if (bbnd >= bignum * dabs(ur22)) { + *scale = 1.f / bbnd; + } + } + + xr2 = br2 * *scale / ur22; + xr1 = *scale * br1 * ur11r - xr2 * (ur11r * ur12); + if (cswap[icmax - 1]) { + x[x_dim1 + 1] = xr2; + x[x_dim1 + 2] = xr1; + } else { + x[x_dim1 + 1] = xr1; + x[x_dim1 + 2] = xr2; + } +/* Computing MAX */ + r__1 = dabs(xr1), r__2 = dabs(xr2); + *xnorm = dmax(r__1,r__2); + +/* Further scaling if norm(A) norm(X) > overflow */ + + if (*xnorm > 1.f && cmax > 1.f) { + if (*xnorm > bignum / cmax) { + temp = cmax / bignum; + x[x_dim1 + 1] = temp * x[x_dim1 + 1]; + x[x_dim1 + 2] = temp * x[x_dim1 + 2]; + *xnorm = temp * *xnorm; + *scale = temp * *scale; + } + } + } else { + +/* + Complex 2x2 system (w is complex) + + Find the largest element in C +*/ + + ci[0] = -(*wi) * *d1; + ci[1] = 0.f; + ci[2] = 0.f; + ci[3] = -(*wi) * *d2; + cmax = 0.f; + icmax = 0; + + for (j = 1; j <= 4; ++j) { + if ((r__1 = crv[j - 1], dabs(r__1)) + (r__2 = civ[j - 1], + dabs(r__2)) > cmax) { + cmax = (r__1 = crv[j - 1], dabs(r__1)) + (r__2 = civ[j - + 1], dabs(r__2)); + icmax = j; + } +/* L20: */ + } + +/* If norm(C) < SMINI, use SMINI*identity. */ + + if (cmax < smini) { +/* Computing MAX */ + r__5 = (r__1 = b[b_dim1 + 1], dabs(r__1)) + (r__2 = b[(b_dim1 + << 1) + 1], dabs(r__2)), r__6 = (r__3 = b[b_dim1 + 2], + dabs(r__3)) + (r__4 = b[(b_dim1 << 1) + 2], dabs( + r__4)); + bnorm = dmax(r__5,r__6); + if (smini < 1.f && bnorm > 1.f) { + if (bnorm > bignum * smini) { + *scale = 1.f / bnorm; + } + } + temp = *scale / smini; + x[x_dim1 + 1] = temp * b[b_dim1 + 1]; + x[x_dim1 + 2] = temp * b[b_dim1 + 2]; + x[(x_dim1 << 1) + 1] = temp * b[(b_dim1 << 1) + 1]; + x[(x_dim1 << 1) + 2] = temp * b[(b_dim1 << 1) + 2]; + *xnorm = temp * bnorm; + *info = 1; + return 0; + } + +/* Gaussian elimination with complete pivoting. */ + + ur11 = crv[icmax - 1]; + ui11 = civ[icmax - 1]; + cr21 = crv[ipivot[(icmax << 2) - 3] - 1]; + ci21 = civ[ipivot[(icmax << 2) - 3] - 1]; + ur12 = crv[ipivot[(icmax << 2) - 2] - 1]; + ui12 = civ[ipivot[(icmax << 2) - 2] - 1]; + cr22 = crv[ipivot[(icmax << 2) - 1] - 1]; + ci22 = civ[ipivot[(icmax << 2) - 1] - 1]; + if (icmax == 1 || icmax == 4) { + +/* Code when off-diagonals of pivoted C are real */ + + if (dabs(ur11) > dabs(ui11)) { + temp = ui11 / ur11; +/* Computing 2nd power */ + r__1 = temp; + ur11r = 1.f / (ur11 * (r__1 * r__1 + 1.f)); + ui11r = -temp * ur11r; + } else { + temp = ur11 / ui11; +/* Computing 2nd power */ + r__1 = temp; + ui11r = -1.f / (ui11 * (r__1 * r__1 + 1.f)); + ur11r = -temp * ui11r; + } + lr21 = cr21 * ur11r; + li21 = cr21 * ui11r; + ur12s = ur12 * ur11r; + ui12s = ur12 * ui11r; + ur22 = cr22 - ur12 * lr21; + ui22 = ci22 - ur12 * li21; + } else { + +/* Code when diagonals of pivoted C are real */ + + ur11r = 1.f / ur11; + ui11r = 0.f; + lr21 = cr21 * ur11r; + li21 = ci21 * ur11r; + ur12s = ur12 * ur11r; + ui12s = ui12 * ur11r; + ur22 = cr22 - ur12 * lr21 + ui12 * li21; + ui22 = -ur12 * li21 - ui12 * lr21; + } + u22abs = dabs(ur22) + dabs(ui22); + +/* If smaller pivot < SMINI, use SMINI */ + + if (u22abs < smini) { + ur22 = smini; + ui22 = 0.f; + *info = 1; + } + if (rswap[icmax - 1]) { + br2 = b[b_dim1 + 1]; + br1 = b[b_dim1 + 2]; + bi2 = b[(b_dim1 << 1) + 1]; + bi1 = b[(b_dim1 << 1) + 2]; + } else { + br1 = b[b_dim1 + 1]; + br2 = b[b_dim1 + 2]; + bi1 = b[(b_dim1 << 1) + 1]; + bi2 = b[(b_dim1 << 1) + 2]; + } + br2 = br2 - lr21 * br1 + li21 * bi1; + bi2 = bi2 - li21 * br1 - lr21 * bi1; +/* Computing MAX */ + r__1 = (dabs(br1) + dabs(bi1)) * (u22abs * (dabs(ur11r) + dabs( + ui11r))), r__2 = dabs(br2) + dabs(bi2); + bbnd = dmax(r__1,r__2); + if (bbnd > 1.f && u22abs < 1.f) { + if (bbnd >= bignum * u22abs) { + *scale = 1.f / bbnd; + br1 = *scale * br1; + bi1 = *scale * bi1; + br2 = *scale * br2; + bi2 = *scale * bi2; + } + } + + sladiv_(&br2, &bi2, &ur22, &ui22, &xr2, &xi2); + xr1 = ur11r * br1 - ui11r * bi1 - ur12s * xr2 + ui12s * xi2; + xi1 = ui11r * br1 + ur11r * bi1 - ui12s * xr2 - ur12s * xi2; + if (cswap[icmax - 1]) { + x[x_dim1 + 1] = xr2; + x[x_dim1 + 2] = xr1; + x[(x_dim1 << 1) + 1] = xi2; + x[(x_dim1 << 1) + 2] = xi1; + } else { + x[x_dim1 + 1] = xr1; + x[x_dim1 + 2] = xr2; + x[(x_dim1 << 1) + 1] = xi1; + x[(x_dim1 << 1) + 2] = xi2; + } +/* Computing MAX */ + r__1 = dabs(xr1) + dabs(xi1), r__2 = dabs(xr2) + dabs(xi2); + *xnorm = dmax(r__1,r__2); + +/* Further scaling if norm(A) norm(X) > overflow */ + + if (*xnorm > 1.f && cmax > 1.f) { + if (*xnorm > bignum / cmax) { + temp = cmax / bignum; + x[x_dim1 + 1] = temp * x[x_dim1 + 1]; + x[x_dim1 + 2] = temp * x[x_dim1 + 2]; + x[(x_dim1 << 1) + 1] = temp * x[(x_dim1 << 1) + 1]; + x[(x_dim1 << 1) + 2] = temp * x[(x_dim1 << 1) + 2]; + *xnorm = temp * *xnorm; + *scale = temp * *scale; + } + } + } + } + + return 0; + +/* End of SLALN2 */ + +} /* slaln2_ */ + +#undef crv +#undef civ +#undef cr +#undef ci + + +doublereal slamch_(char *cmach) +{ + /* Initialized data */ + + static logical first = TRUE_; + + /* System generated locals */ + integer i__1; + real ret_val; + + /* Builtin functions */ + double pow_ri(real *, integer *); + + /* Local variables */ + static real t; + static integer it; + static real rnd, eps, base; + static integer beta; + static real emin, prec, emax; + static integer imin, imax; + static logical lrnd; + static real rmin, rmax, rmach; + extern logical lsame_(char *, char *); + static real small, sfmin; + extern /* Subroutine */ int slamc2_(integer *, integer *, logical *, real + *, integer *, real *, integer *, real *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLAMCH determines single precision machine parameters. + + Arguments + ========= + + CMACH (input) CHARACTER*1 + Specifies the value to be returned by SLAMCH: + = 'E' or 'e', SLAMCH := eps + = 'S' or 's , SLAMCH := sfmin + = 'B' or 'b', SLAMCH := base + = 'P' or 'p', SLAMCH := eps*base + = 'N' or 'n', SLAMCH := t + = 'R' or 'r', SLAMCH := rnd + = 'M' or 'm', SLAMCH := emin + = 'U' or 'u', SLAMCH := rmin + = 'L' or 'l', SLAMCH := emax + = 'O' or 'o', SLAMCH := rmax + + where + + eps = relative machine precision + sfmin = safe minimum, such that 1/sfmin does not overflow + base = base of the machine + prec = eps*base + t = number of (base) digits in the mantissa + rnd = 1.0 when rounding occurs in addition, 0.0 otherwise + emin = minimum exponent before (gradual) underflow + rmin = underflow threshold - base**(emin-1) + emax = largest exponent before overflow + rmax = overflow threshold - (base**emax)*(1-eps) + + ===================================================================== +*/ + + + if (first) { + first = FALSE_; + slamc2_(&beta, &it, &lrnd, &eps, &imin, &rmin, &imax, &rmax); + base = (real) beta; + t = (real) it; + if (lrnd) { + rnd = 1.f; + i__1 = 1 - it; + eps = pow_ri(&base, &i__1) / 2; + } else { + rnd = 0.f; + i__1 = 1 - it; + eps = pow_ri(&base, &i__1); + } + prec = eps * base; + emin = (real) imin; + emax = (real) imax; + sfmin = rmin; + small = 1.f / rmax; + if (small >= sfmin) { + +/* + Use SMALL plus a bit, to avoid the possibility of rounding + causing overflow when computing 1/sfmin. +*/ + + sfmin = small * (eps + 1.f); + } + } + + if (lsame_(cmach, "E")) { + rmach = eps; + } else if (lsame_(cmach, "S")) { + rmach = sfmin; + } else if (lsame_(cmach, "B")) { + rmach = base; + } else if (lsame_(cmach, "P")) { + rmach = prec; + } else if (lsame_(cmach, "N")) { + rmach = t; + } else if (lsame_(cmach, "R")) { + rmach = rnd; + } else if (lsame_(cmach, "M")) { + rmach = emin; + } else if (lsame_(cmach, "U")) { + rmach = rmin; + } else if (lsame_(cmach, "L")) { + rmach = emax; + } else if (lsame_(cmach, "O")) { + rmach = rmax; + } + + ret_val = rmach; + return ret_val; + +/* End of SLAMCH */ + +} /* slamch_ */ + + +/* *********************************************************************** */ + +/* Subroutine */ int slamc1_(integer *beta, integer *t, logical *rnd, logical + *ieee1) +{ + /* Initialized data */ + + static logical first = TRUE_; + + /* System generated locals */ + real r__1, r__2; + + /* Local variables */ + static real a, b, c__, f, t1, t2; + static integer lt; + static real one, qtr; + static logical lrnd; + static integer lbeta; + static real savec; + static logical lieee1; + extern doublereal slamc3_(real *, real *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLAMC1 determines the machine parameters given by BETA, T, RND, and + IEEE1. + + Arguments + ========= + + BETA (output) INTEGER + The base of the machine. + + T (output) INTEGER + The number of ( BETA ) digits in the mantissa. + + RND (output) LOGICAL + Specifies whether proper rounding ( RND = .TRUE. ) or + chopping ( RND = .FALSE. ) occurs in addition. This may not + be a reliable guide to the way in which the machine performs + its arithmetic. + + IEEE1 (output) LOGICAL + Specifies whether rounding appears to be done in the IEEE + 'round to nearest' style. + + Further Details + =============== + + The routine is based on the routine ENVRON by Malcolm and + incorporates suggestions by Gentleman and Marovich. See + + Malcolm M. A. (1972) Algorithms to reveal properties of + floating-point arithmetic. Comms. of the ACM, 15, 949-951. + + Gentleman W. M. and Marovich S. B. (1974) More on algorithms + that reveal properties of floating point arithmetic units. + Comms. of the ACM, 17, 276-277. + + ===================================================================== +*/ + + + if (first) { + first = FALSE_; + one = 1.f; + +/* + LBETA, LIEEE1, LT and LRND are the local values of BETA, + IEEE1, T and RND. + + Throughout this routine we use the function SLAMC3 to ensure + that relevant values are stored and not held in registers, or + are not affected by optimizers. + + Compute a = 2.0**m with the smallest positive integer m such + that + + fl( a + 1.0 ) = a. +*/ + + a = 1.f; + c__ = 1.f; + +/* + WHILE( C.EQ.ONE )LOOP */ +L10: + if (c__ == one) { + a *= 2; + c__ = slamc3_(&a, &one); + r__1 = -a; + c__ = slamc3_(&c__, &r__1); + goto L10; + } +/* + + END WHILE + + Now compute b = 2.0**m with the smallest positive integer m + such that + + fl( a + b ) .gt. a. +*/ + + b = 1.f; + c__ = slamc3_(&a, &b); + +/* + WHILE( C.EQ.A )LOOP */ +L20: + if (c__ == a) { + b *= 2; + c__ = slamc3_(&a, &b); + goto L20; + } +/* + + END WHILE + + Now compute the base. a and c are neighbouring floating point + numbers in the interval ( beta**t, beta**( t + 1 ) ) and so + their difference is beta. Adding 0.25 to c is to ensure that it + is truncated to beta and not ( beta - 1 ). +*/ + + qtr = one / 4; + savec = c__; + r__1 = -a; + c__ = slamc3_(&c__, &r__1); + lbeta = c__ + qtr; + +/* + Now determine whether rounding or chopping occurs, by adding a + bit less than beta/2 and a bit more than beta/2 to a. +*/ + + b = (real) lbeta; + r__1 = b / 2; + r__2 = -b / 100; + f = slamc3_(&r__1, &r__2); + c__ = slamc3_(&f, &a); + if (c__ == a) { + lrnd = TRUE_; + } else { + lrnd = FALSE_; + } + r__1 = b / 2; + r__2 = b / 100; + f = slamc3_(&r__1, &r__2); + c__ = slamc3_(&f, &a); + if (lrnd && c__ == a) { + lrnd = FALSE_; + } + +/* + Try and decide whether rounding is done in the IEEE 'round to + nearest' style. B/2 is half a unit in the last place of the two + numbers A and SAVEC. Furthermore, A is even, i.e. has last bit + zero, and SAVEC is odd. Thus adding B/2 to A should not change + A, but adding B/2 to SAVEC should change SAVEC. +*/ + + r__1 = b / 2; + t1 = slamc3_(&r__1, &a); + r__1 = b / 2; + t2 = slamc3_(&r__1, &savec); + lieee1 = t1 == a && t2 > savec && lrnd; + +/* + Now find the mantissa, t. It should be the integer part of + log to the base beta of a, however it is safer to determine t + by powering. So we find t as the smallest positive integer for + which + + fl( beta**t + 1.0 ) = 1.0. +*/ + + lt = 0; + a = 1.f; + c__ = 1.f; + +/* + WHILE( C.EQ.ONE )LOOP */ +L30: + if (c__ == one) { + ++lt; + a *= lbeta; + c__ = slamc3_(&a, &one); + r__1 = -a; + c__ = slamc3_(&c__, &r__1); + goto L30; + } +/* + END WHILE */ + + } + + *beta = lbeta; + *t = lt; + *rnd = lrnd; + *ieee1 = lieee1; + return 0; + +/* End of SLAMC1 */ + +} /* slamc1_ */ + + +/* *********************************************************************** */ + +/* Subroutine */ int slamc2_(integer *beta, integer *t, logical *rnd, real * + eps, integer *emin, real *rmin, integer *emax, real *rmax) +{ + /* Initialized data */ + + static logical first = TRUE_; + static logical iwarn = FALSE_; + + /* Format strings */ + static char fmt_9999[] = "(//\002 WARNING. The value EMIN may be incorre" + "ct:-\002,\002 EMIN = \002,i8,/\002 If, after inspection, the va" + "lue EMIN looks\002,\002 acceptable please comment out \002,/\002" + " the IF block as marked within the code of routine\002,\002 SLAM" + "C2,\002,/\002 otherwise supply EMIN explicitly.\002,/)"; + + /* System generated locals */ + integer i__1; + real r__1, r__2, r__3, r__4, r__5; + + /* Builtin functions */ + double pow_ri(real *, integer *); + integer s_wsfe(cilist *), do_fio(integer *, char *, ftnlen), e_wsfe(void); + + /* Local variables */ + static real a, b, c__; + static integer i__, lt; + static real one, two; + static logical ieee; + static real half; + static logical lrnd; + static real leps, zero; + static integer lbeta; + static real rbase; + static integer lemin, lemax, gnmin; + static real small; + static integer gpmin; + static real third, lrmin, lrmax, sixth; + static logical lieee1; + extern /* Subroutine */ int slamc1_(integer *, integer *, logical *, + logical *); + extern doublereal slamc3_(real *, real *); + extern /* Subroutine */ int slamc4_(integer *, real *, integer *), + slamc5_(integer *, integer *, integer *, logical *, integer *, + real *); + static integer ngnmin, ngpmin; + + /* Fortran I/O blocks */ + static cilist io___620 = { 0, 6, 0, fmt_9999, 0 }; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLAMC2 determines the machine parameters specified in its argument + list. + + Arguments + ========= + + BETA (output) INTEGER + The base of the machine. + + T (output) INTEGER + The number of ( BETA ) digits in the mantissa. + + RND (output) LOGICAL + Specifies whether proper rounding ( RND = .TRUE. ) or + chopping ( RND = .FALSE. ) occurs in addition. This may not + be a reliable guide to the way in which the machine performs + its arithmetic. + + EPS (output) REAL + The smallest positive number such that + + fl( 1.0 - EPS ) .LT. 1.0, + + where fl denotes the computed value. + + EMIN (output) INTEGER + The minimum exponent before (gradual) underflow occurs. + + RMIN (output) REAL + The smallest normalized number for the machine, given by + BASE**( EMIN - 1 ), where BASE is the floating point value + of BETA. + + EMAX (output) INTEGER + The maximum exponent before overflow occurs. + + RMAX (output) REAL + The largest positive number for the machine, given by + BASE**EMAX * ( 1 - EPS ), where BASE is the floating point + value of BETA. + + Further Details + =============== + + The computation of EPS is based on a routine PARANOIA by + W. Kahan of the University of California at Berkeley. + + ===================================================================== +*/ + + + if (first) { + first = FALSE_; + zero = 0.f; + one = 1.f; + two = 2.f; + +/* + LBETA, LT, LRND, LEPS, LEMIN and LRMIN are the local values of + BETA, T, RND, EPS, EMIN and RMIN. + + Throughout this routine we use the function SLAMC3 to ensure + that relevant values are stored and not held in registers, or + are not affected by optimizers. + + SLAMC1 returns the parameters LBETA, LT, LRND and LIEEE1. +*/ + + slamc1_(&lbeta, <, &lrnd, &lieee1); + +/* Start to find EPS. */ + + b = (real) lbeta; + i__1 = -lt; + a = pow_ri(&b, &i__1); + leps = a; + +/* Try some tricks to see whether or not this is the correct EPS. */ + + b = two / 3; + half = one / 2; + r__1 = -half; + sixth = slamc3_(&b, &r__1); + third = slamc3_(&sixth, &sixth); + r__1 = -half; + b = slamc3_(&third, &r__1); + b = slamc3_(&b, &sixth); + b = dabs(b); + if (b < leps) { + b = leps; + } + + leps = 1.f; + +/* + WHILE( ( LEPS.GT.B ).AND.( B.GT.ZERO ) )LOOP */ +L10: + if (leps > b && b > zero) { + leps = b; + r__1 = half * leps; +/* Computing 5th power */ + r__3 = two, r__4 = r__3, r__3 *= r__3; +/* Computing 2nd power */ + r__5 = leps; + r__2 = r__4 * (r__3 * r__3) * (r__5 * r__5); + c__ = slamc3_(&r__1, &r__2); + r__1 = -c__; + c__ = slamc3_(&half, &r__1); + b = slamc3_(&half, &c__); + r__1 = -b; + c__ = slamc3_(&half, &r__1); + b = slamc3_(&half, &c__); + goto L10; + } +/* + END WHILE */ + + if (a < leps) { + leps = a; + } + +/* + Computation of EPS complete. + + Now find EMIN. Let A = + or - 1, and + or - (1 + BASE**(-3)). + Keep dividing A by BETA until (gradual) underflow occurs. This + is detected when we cannot recover the previous A. +*/ + + rbase = one / lbeta; + small = one; + for (i__ = 1; i__ <= 3; ++i__) { + r__1 = small * rbase; + small = slamc3_(&r__1, &zero); +/* L20: */ + } + a = slamc3_(&one, &small); + slamc4_(&ngpmin, &one, &lbeta); + r__1 = -one; + slamc4_(&ngnmin, &r__1, &lbeta); + slamc4_(&gpmin, &a, &lbeta); + r__1 = -a; + slamc4_(&gnmin, &r__1, &lbeta); + ieee = FALSE_; + + if (ngpmin == ngnmin && gpmin == gnmin) { + if (ngpmin == gpmin) { + lemin = ngpmin; +/* + ( Non twos-complement machines, no gradual underflow; + e.g., VAX ) +*/ + } else if (gpmin - ngpmin == 3) { + lemin = ngpmin - 1 + lt; + ieee = TRUE_; +/* + ( Non twos-complement machines, with gradual underflow; + e.g., IEEE standard followers ) +*/ + } else { + lemin = min(ngpmin,gpmin); +/* ( A guess; no known machine ) */ + iwarn = TRUE_; + } + + } else if (ngpmin == gpmin && ngnmin == gnmin) { + if ((i__1 = ngpmin - ngnmin, abs(i__1)) == 1) { + lemin = max(ngpmin,ngnmin); +/* + ( Twos-complement machines, no gradual underflow; + e.g., CYBER 205 ) +*/ + } else { + lemin = min(ngpmin,ngnmin); +/* ( A guess; no known machine ) */ + iwarn = TRUE_; + } + + } else if ((i__1 = ngpmin - ngnmin, abs(i__1)) == 1 && gpmin == gnmin) + { + if (gpmin - min(ngpmin,ngnmin) == 3) { + lemin = max(ngpmin,ngnmin) - 1 + lt; +/* + ( Twos-complement machines with gradual underflow; + no known machine ) +*/ + } else { + lemin = min(ngpmin,ngnmin); +/* ( A guess; no known machine ) */ + iwarn = TRUE_; + } + + } else { +/* Computing MIN */ + i__1 = min(ngpmin,ngnmin), i__1 = min(i__1,gpmin); + lemin = min(i__1,gnmin); +/* ( A guess; no known machine ) */ + iwarn = TRUE_; + } +/* + ** + Comment out this if block if EMIN is ok +*/ + if (iwarn) { + first = TRUE_; + s_wsfe(&io___620); + do_fio(&c__1, (char *)&lemin, (ftnlen)sizeof(integer)); + e_wsfe(); + } +/* + ** + + Assume IEEE arithmetic if we found denormalised numbers above, + or if arithmetic seems to round in the IEEE style, determined + in routine SLAMC1. A true IEEE machine should have both things + true; however, faulty machines may have one or the other. +*/ + + ieee = ieee || lieee1; + +/* + Compute RMIN by successive division by BETA. We could compute + RMIN as BASE**( EMIN - 1 ), but some machines underflow during + this computation. +*/ + + lrmin = 1.f; + i__1 = 1 - lemin; + for (i__ = 1; i__ <= i__1; ++i__) { + r__1 = lrmin * rbase; + lrmin = slamc3_(&r__1, &zero); +/* L30: */ + } + +/* Finally, call SLAMC5 to compute EMAX and RMAX. */ + + slamc5_(&lbeta, <, &lemin, &ieee, &lemax, &lrmax); + } + + *beta = lbeta; + *t = lt; + *rnd = lrnd; + *eps = leps; + *emin = lemin; + *rmin = lrmin; + *emax = lemax; + *rmax = lrmax; + + return 0; + + +/* End of SLAMC2 */ + +} /* slamc2_ */ + + +/* *********************************************************************** */ + +doublereal slamc3_(real *a, real *b) +{ + /* System generated locals */ + real ret_val; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLAMC3 is intended to force A and B to be stored prior to doing + the addition of A and B , for use in situations where optimizers + might hold one of these in a register. + + Arguments + ========= + + A, B (input) REAL + The values A and B. + + ===================================================================== +*/ + + + ret_val = *a + *b; + + return ret_val; + +/* End of SLAMC3 */ + +} /* slamc3_ */ + + +/* *********************************************************************** */ + +/* Subroutine */ int slamc4_(integer *emin, real *start, integer *base) +{ + /* System generated locals */ + integer i__1; + real r__1; + + /* Local variables */ + static real a; + static integer i__; + static real b1, b2, c1, c2, d1, d2, one, zero, rbase; + extern doublereal slamc3_(real *, real *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLAMC4 is a service routine for SLAMC2. + + Arguments + ========= + + EMIN (output) EMIN + The minimum exponent before (gradual) underflow, computed by + setting A = START and dividing by BASE until the previous A + can not be recovered. + + START (input) REAL + The starting point for determining EMIN. + + BASE (input) INTEGER + The base of the machine. + + ===================================================================== +*/ + + + a = *start; + one = 1.f; + rbase = one / *base; + zero = 0.f; + *emin = 1; + r__1 = a * rbase; + b1 = slamc3_(&r__1, &zero); + c1 = a; + c2 = a; + d1 = a; + d2 = a; +/* + + WHILE( ( C1.EQ.A ).AND.( C2.EQ.A ).AND. + $ ( D1.EQ.A ).AND.( D2.EQ.A ) )LOOP +*/ +L10: + if (c1 == a && c2 == a && d1 == a && d2 == a) { + --(*emin); + a = b1; + r__1 = a / *base; + b1 = slamc3_(&r__1, &zero); + r__1 = b1 * *base; + c1 = slamc3_(&r__1, &zero); + d1 = zero; + i__1 = *base; + for (i__ = 1; i__ <= i__1; ++i__) { + d1 += b1; +/* L20: */ + } + r__1 = a * rbase; + b2 = slamc3_(&r__1, &zero); + r__1 = b2 / rbase; + c2 = slamc3_(&r__1, &zero); + d2 = zero; + i__1 = *base; + for (i__ = 1; i__ <= i__1; ++i__) { + d2 += b2; +/* L30: */ + } + goto L10; + } +/* + END WHILE */ + + return 0; + +/* End of SLAMC4 */ + +} /* slamc4_ */ + + +/* *********************************************************************** */ + +/* Subroutine */ int slamc5_(integer *beta, integer *p, integer *emin, + logical *ieee, integer *emax, real *rmax) +{ + /* System generated locals */ + integer i__1; + real r__1; + + /* Local variables */ + static integer i__; + static real y, z__; + static integer try__, lexp; + static real oldy; + static integer uexp, nbits; + extern doublereal slamc3_(real *, real *); + static real recbas; + static integer exbits, expsum; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLAMC5 attempts to compute RMAX, the largest machine floating-point + number, without overflow. It assumes that EMAX + abs(EMIN) sum + approximately to a power of 2. It will fail on machines where this + assumption does not hold, for example, the Cyber 205 (EMIN = -28625, + EMAX = 28718). It will also fail if the value supplied for EMIN is + too large (i.e. too close to zero), probably with overflow. + + Arguments + ========= + + BETA (input) INTEGER + The base of floating-point arithmetic. + + P (input) INTEGER + The number of base BETA digits in the mantissa of a + floating-point value. + + EMIN (input) INTEGER + The minimum exponent before (gradual) underflow. + + IEEE (input) LOGICAL + A logical flag specifying whether or not the arithmetic + system is thought to comply with the IEEE standard. + + EMAX (output) INTEGER + The largest exponent before overflow + + RMAX (output) REAL + The largest machine floating-point number. + + ===================================================================== + + + First compute LEXP and UEXP, two powers of 2 that bound + abs(EMIN). We then assume that EMAX + abs(EMIN) will sum + approximately to the bound that is closest to abs(EMIN). + (EMAX is the exponent of the required number RMAX). +*/ + + lexp = 1; + exbits = 1; +L10: + try__ = lexp << 1; + if (try__ <= -(*emin)) { + lexp = try__; + ++exbits; + goto L10; + } + if (lexp == -(*emin)) { + uexp = lexp; + } else { + uexp = try__; + ++exbits; + } + +/* + Now -LEXP is less than or equal to EMIN, and -UEXP is greater + than or equal to EMIN. EXBITS is the number of bits needed to + store the exponent. +*/ + + if (uexp + *emin > -lexp - *emin) { + expsum = lexp << 1; + } else { + expsum = uexp << 1; + } + +/* + EXPSUM is the exponent range, approximately equal to + EMAX - EMIN + 1 . +*/ + + *emax = expsum + *emin - 1; + nbits = exbits + 1 + *p; + +/* + NBITS is the total number of bits needed to store a + floating-point number. +*/ + + if (nbits % 2 == 1 && *beta == 2) { + +/* + Either there are an odd number of bits used to store a + floating-point number, which is unlikely, or some bits are + not used in the representation of numbers, which is possible, + (e.g. Cray machines) or the mantissa has an implicit bit, + (e.g. IEEE machines, Dec Vax machines), which is perhaps the + most likely. We have to assume the last alternative. + If this is true, then we need to reduce EMAX by one because + there must be some way of representing zero in an implicit-bit + system. On machines like Cray, we are reducing EMAX by one + unnecessarily. +*/ + + --(*emax); + } + + if (*ieee) { + +/* + Assume we are on an IEEE machine which reserves one exponent + for infinity and NaN. +*/ + + --(*emax); + } + +/* + Now create RMAX, the largest machine number, which should + be equal to (1.0 - BETA**(-P)) * BETA**EMAX . + + First compute 1.0 - BETA**(-P), being careful that the + result is less than 1.0 . +*/ + + recbas = 1.f / *beta; + z__ = *beta - 1.f; + y = 0.f; + i__1 = *p; + for (i__ = 1; i__ <= i__1; ++i__) { + z__ *= recbas; + if (y < 1.f) { + oldy = y; + } + y = slamc3_(&y, &z__); +/* L20: */ + } + if (y >= 1.f) { + y = oldy; + } + +/* Now multiply by BETA**EMAX to get RMAX. */ + + i__1 = *emax; + for (i__ = 1; i__ <= i__1; ++i__) { + r__1 = y * *beta; + y = slamc3_(&r__1, &c_b29); +/* L30: */ + } + + *rmax = y; + return 0; + +/* End of SLAMC5 */ + +} /* slamc5_ */ + +/* Subroutine */ int slamrg_(integer *n1, integer *n2, real *a, integer * + strd1, integer *strd2, integer *index) +{ + /* System generated locals */ + integer i__1; + + /* Local variables */ + static integer i__, ind1, ind2, n1sv, n2sv; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + September 30, 1994 + + + Purpose + ======= + + SLAMRG will create a permutation list which will merge the elements + of A (which is composed of two independently sorted sets) into a + single set which is sorted in ascending order. + + Arguments + ========= + + N1 (input) INTEGER + N2 (input) INTEGER + These arguements contain the respective lengths of the two + sorted lists to be merged. + + A (input) REAL array, dimension (N1+N2) + The first N1 elements of A contain a list of numbers which + are sorted in either ascending or descending order. Likewise + for the final N2 elements. + + STRD1 (input) INTEGER + STRD2 (input) INTEGER + These are the strides to be taken through the array A. + Allowable strides are 1 and -1. They indicate whether a + subset of A is sorted in ascending (STRDx = 1) or descending + (STRDx = -1) order. + + INDEX (output) INTEGER array, dimension (N1+N2) + On exit this array will contain a permutation such that + if B( I ) = A( INDEX( I ) ) for I=1,N1+N2, then B will be + sorted in ascending order. + + ===================================================================== +*/ + + + /* Parameter adjustments */ + --index; + --a; + + /* Function Body */ + n1sv = *n1; + n2sv = *n2; + if (*strd1 > 0) { + ind1 = 1; + } else { + ind1 = *n1; + } + if (*strd2 > 0) { + ind2 = *n1 + 1; + } else { + ind2 = *n1 + *n2; + } + i__ = 1; +/* while ( (N1SV > 0) & (N2SV > 0) ) */ +L10: + if (n1sv > 0 && n2sv > 0) { + if (a[ind1] <= a[ind2]) { + index[i__] = ind1; + ++i__; + ind1 += *strd1; + --n1sv; + } else { + index[i__] = ind2; + ++i__; + ind2 += *strd2; + --n2sv; + } + goto L10; + } +/* end while */ + if (n1sv == 0) { + i__1 = n2sv; + for (n1sv = 1; n1sv <= i__1; ++n1sv) { + index[i__] = ind2; + ++i__; + ind2 += *strd2; +/* L20: */ + } + } else { +/* N2SV .EQ. 0 */ + i__1 = n1sv; + for (n2sv = 1; n2sv <= i__1; ++n2sv) { + index[i__] = ind1; + ++i__; + ind1 += *strd1; +/* L30: */ + } + } + + return 0; + +/* End of SLAMRG */ + +} /* slamrg_ */ + +doublereal slange_(char *norm, integer *m, integer *n, real *a, integer *lda, + real *work) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2; + real ret_val, r__1, r__2, r__3; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static integer i__, j; + static real sum, scale; + extern logical lsame_(char *, char *); + static real value; + extern /* Subroutine */ int slassq_(integer *, real *, integer *, real *, + real *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLANGE returns the value of the one norm, or the Frobenius norm, or + the infinity norm, or the element of largest absolute value of a + real matrix A. + + Description + =========== + + SLANGE returns the value + + SLANGE = ( max(abs(A(i,j))), NORM = 'M' or 'm' + ( + ( norm1(A), NORM = '1', 'O' or 'o' + ( + ( normI(A), NORM = 'I' or 'i' + ( + ( normF(A), NORM = 'F', 'f', 'E' or 'e' + + where norm1 denotes the one norm of a matrix (maximum column sum), + normI denotes the infinity norm of a matrix (maximum row sum) and + normF denotes the Frobenius norm of a matrix (square root of sum of + squares). Note that max(abs(A(i,j))) is not a matrix norm. + + Arguments + ========= + + NORM (input) CHARACTER*1 + Specifies the value to be returned in SLANGE as described + above. + + M (input) INTEGER + The number of rows of the matrix A. M >= 0. When M = 0, + SLANGE is set to zero. + + N (input) INTEGER + The number of columns of the matrix A. N >= 0. When N = 0, + SLANGE is set to zero. + + A (input) REAL array, dimension (LDA,N) + The m by n matrix A. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(M,1). + + WORK (workspace) REAL array, dimension (LWORK), + where LWORK >= M when NORM = 'I'; otherwise, WORK is not + referenced. + + ===================================================================== +*/ + + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --work; + + /* Function Body */ + if (min(*m,*n) == 0) { + value = 0.f; + } else if (lsame_(norm, "M")) { + +/* Find max(abs(A(i,j))). */ + + value = 0.f; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { +/* Computing MAX */ + r__2 = value, r__3 = (r__1 = a[i__ + j * a_dim1], dabs(r__1)); + value = dmax(r__2,r__3); +/* L10: */ + } +/* L20: */ + } + } else if (lsame_(norm, "O") || *(unsigned char *) + norm == '1') { + +/* Find norm1(A). */ + + value = 0.f; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = 0.f; + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + sum += (r__1 = a[i__ + j * a_dim1], dabs(r__1)); +/* L30: */ + } + value = dmax(value,sum); +/* L40: */ + } + } else if (lsame_(norm, "I")) { + +/* Find normI(A). */ + + i__1 = *m; + for (i__ = 1; i__ <= i__1; ++i__) { + work[i__] = 0.f; +/* L50: */ + } + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + work[i__] += (r__1 = a[i__ + j * a_dim1], dabs(r__1)); +/* L60: */ + } +/* L70: */ + } + value = 0.f; + i__1 = *m; + for (i__ = 1; i__ <= i__1; ++i__) { +/* Computing MAX */ + r__1 = value, r__2 = work[i__]; + value = dmax(r__1,r__2); +/* L80: */ + } + } else if (lsame_(norm, "F") || lsame_(norm, "E")) { + +/* Find normF(A). */ + + scale = 0.f; + sum = 1.f; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + slassq_(m, &a[j * a_dim1 + 1], &c__1, &scale, &sum); +/* L90: */ + } + value = scale * sqrt(sum); + } + + ret_val = value; + return ret_val; + +/* End of SLANGE */ + +} /* slange_ */ + +doublereal slanhs_(char *norm, integer *n, real *a, integer *lda, real *work) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3, i__4; + real ret_val, r__1, r__2, r__3; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static integer i__, j; + static real sum, scale; + extern logical lsame_(char *, char *); + static real value; + extern /* Subroutine */ int slassq_(integer *, real *, integer *, real *, + real *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLANHS returns the value of the one norm, or the Frobenius norm, or + the infinity norm, or the element of largest absolute value of a + Hessenberg matrix A. + + Description + =========== + + SLANHS returns the value + + SLANHS = ( max(abs(A(i,j))), NORM = 'M' or 'm' + ( + ( norm1(A), NORM = '1', 'O' or 'o' + ( + ( normI(A), NORM = 'I' or 'i' + ( + ( normF(A), NORM = 'F', 'f', 'E' or 'e' + + where norm1 denotes the one norm of a matrix (maximum column sum), + normI denotes the infinity norm of a matrix (maximum row sum) and + normF denotes the Frobenius norm of a matrix (square root of sum of + squares). Note that max(abs(A(i,j))) is not a matrix norm. + + Arguments + ========= + + NORM (input) CHARACTER*1 + Specifies the value to be returned in SLANHS as described + above. + + N (input) INTEGER + The order of the matrix A. N >= 0. When N = 0, SLANHS is + set to zero. + + A (input) REAL array, dimension (LDA,N) + The n by n upper Hessenberg matrix A; the part of A below the + first sub-diagonal is not referenced. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(N,1). + + WORK (workspace) REAL array, dimension (LWORK), + where LWORK >= N when NORM = 'I'; otherwise, WORK is not + referenced. + + ===================================================================== +*/ + + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --work; + + /* Function Body */ + if (*n == 0) { + value = 0.f; + } else if (lsame_(norm, "M")) { + +/* Find max(abs(A(i,j))). */ + + value = 0.f; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { +/* Computing MIN */ + i__3 = *n, i__4 = j + 1; + i__2 = min(i__3,i__4); + for (i__ = 1; i__ <= i__2; ++i__) { +/* Computing MAX */ + r__2 = value, r__3 = (r__1 = a[i__ + j * a_dim1], dabs(r__1)); + value = dmax(r__2,r__3); +/* L10: */ + } +/* L20: */ + } + } else if (lsame_(norm, "O") || *(unsigned char *) + norm == '1') { + +/* Find norm1(A). */ + + value = 0.f; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = 0.f; +/* Computing MIN */ + i__3 = *n, i__4 = j + 1; + i__2 = min(i__3,i__4); + for (i__ = 1; i__ <= i__2; ++i__) { + sum += (r__1 = a[i__ + j * a_dim1], dabs(r__1)); +/* L30: */ + } + value = dmax(value,sum); +/* L40: */ + } + } else if (lsame_(norm, "I")) { + +/* Find normI(A). */ + + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + work[i__] = 0.f; +/* L50: */ + } + i__1 = *n; + for (j = 1; j <= i__1; ++j) { +/* Computing MIN */ + i__3 = *n, i__4 = j + 1; + i__2 = min(i__3,i__4); + for (i__ = 1; i__ <= i__2; ++i__) { + work[i__] += (r__1 = a[i__ + j * a_dim1], dabs(r__1)); +/* L60: */ + } +/* L70: */ + } + value = 0.f; + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { +/* Computing MAX */ + r__1 = value, r__2 = work[i__]; + value = dmax(r__1,r__2); +/* L80: */ + } + } else if (lsame_(norm, "F") || lsame_(norm, "E")) { + +/* Find normF(A). */ + + scale = 0.f; + sum = 1.f; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { +/* Computing MIN */ + i__3 = *n, i__4 = j + 1; + i__2 = min(i__3,i__4); + slassq_(&i__2, &a[j * a_dim1 + 1], &c__1, &scale, &sum); +/* L90: */ + } + value = scale * sqrt(sum); + } + + ret_val = value; + return ret_val; + +/* End of SLANHS */ + +} /* slanhs_ */ + +doublereal slanst_(char *norm, integer *n, real *d__, real *e) +{ + /* System generated locals */ + integer i__1; + real ret_val, r__1, r__2, r__3, r__4, r__5; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static integer i__; + static real sum, scale; + extern logical lsame_(char *, char *); + static real anorm; + extern /* Subroutine */ int slassq_(integer *, real *, integer *, real *, + real *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SLANST returns the value of the one norm, or the Frobenius norm, or + the infinity norm, or the element of largest absolute value of a + real symmetric tridiagonal matrix A. + + Description + =========== + + SLANST returns the value + + SLANST = ( max(abs(A(i,j))), NORM = 'M' or 'm' + ( + ( norm1(A), NORM = '1', 'O' or 'o' + ( + ( normI(A), NORM = 'I' or 'i' + ( + ( normF(A), NORM = 'F', 'f', 'E' or 'e' + + where norm1 denotes the one norm of a matrix (maximum column sum), + normI denotes the infinity norm of a matrix (maximum row sum) and + normF denotes the Frobenius norm of a matrix (square root of sum of + squares). Note that max(abs(A(i,j))) is not a matrix norm. + + Arguments + ========= + + NORM (input) CHARACTER*1 + Specifies the value to be returned in SLANST as described + above. + + N (input) INTEGER + The order of the matrix A. N >= 0. When N = 0, SLANST is + set to zero. + + D (input) REAL array, dimension (N) + The diagonal elements of A. + + E (input) REAL array, dimension (N-1) + The (n-1) sub-diagonal or super-diagonal elements of A. + + ===================================================================== +*/ + + + /* Parameter adjustments */ + --e; + --d__; + + /* Function Body */ + if (*n <= 0) { + anorm = 0.f; + } else if (lsame_(norm, "M")) { + +/* Find max(abs(A(i,j))). */ + + anorm = (r__1 = d__[*n], dabs(r__1)); + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { +/* Computing MAX */ + r__2 = anorm, r__3 = (r__1 = d__[i__], dabs(r__1)); + anorm = dmax(r__2,r__3); +/* Computing MAX */ + r__2 = anorm, r__3 = (r__1 = e[i__], dabs(r__1)); + anorm = dmax(r__2,r__3); +/* L10: */ + } + } else if (lsame_(norm, "O") || *(unsigned char *) + norm == '1' || lsame_(norm, "I")) { + +/* Find norm1(A). */ + + if (*n == 1) { + anorm = dabs(d__[1]); + } else { +/* Computing MAX */ + r__3 = dabs(d__[1]) + dabs(e[1]), r__4 = (r__1 = e[*n - 1], dabs( + r__1)) + (r__2 = d__[*n], dabs(r__2)); + anorm = dmax(r__3,r__4); + i__1 = *n - 1; + for (i__ = 2; i__ <= i__1; ++i__) { +/* Computing MAX */ + r__4 = anorm, r__5 = (r__1 = d__[i__], dabs(r__1)) + (r__2 = + e[i__], dabs(r__2)) + (r__3 = e[i__ - 1], dabs(r__3)); + anorm = dmax(r__4,r__5); +/* L20: */ + } + } + } else if (lsame_(norm, "F") || lsame_(norm, "E")) { + +/* Find normF(A). */ + + scale = 0.f; + sum = 1.f; + if (*n > 1) { + i__1 = *n - 1; + slassq_(&i__1, &e[1], &c__1, &scale, &sum); + sum *= 2; + } + slassq_(n, &d__[1], &c__1, &scale, &sum); + anorm = scale * sqrt(sum); + } + + ret_val = anorm; + return ret_val; + +/* End of SLANST */ + +} /* slanst_ */ + +doublereal slansy_(char *norm, char *uplo, integer *n, real *a, integer *lda, + real *work) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2; + real ret_val, r__1, r__2, r__3; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static integer i__, j; + static real sum, absa, scale; + extern logical lsame_(char *, char *); + static real value; + extern /* Subroutine */ int slassq_(integer *, real *, integer *, real *, + real *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLANSY returns the value of the one norm, or the Frobenius norm, or + the infinity norm, or the element of largest absolute value of a + real symmetric matrix A. + + Description + =========== + + SLANSY returns the value + + SLANSY = ( max(abs(A(i,j))), NORM = 'M' or 'm' + ( + ( norm1(A), NORM = '1', 'O' or 'o' + ( + ( normI(A), NORM = 'I' or 'i' + ( + ( normF(A), NORM = 'F', 'f', 'E' or 'e' + + where norm1 denotes the one norm of a matrix (maximum column sum), + normI denotes the infinity norm of a matrix (maximum row sum) and + normF denotes the Frobenius norm of a matrix (square root of sum of + squares). Note that max(abs(A(i,j))) is not a matrix norm. + + Arguments + ========= + + NORM (input) CHARACTER*1 + Specifies the value to be returned in SLANSY as described + above. + + UPLO (input) CHARACTER*1 + Specifies whether the upper or lower triangular part of the + symmetric matrix A is to be referenced. + = 'U': Upper triangular part of A is referenced + = 'L': Lower triangular part of A is referenced + + N (input) INTEGER + The order of the matrix A. N >= 0. When N = 0, SLANSY is + set to zero. + + A (input) REAL array, dimension (LDA,N) + The symmetric matrix A. If UPLO = 'U', the leading n by n + upper triangular part of A contains the upper triangular part + of the matrix A, and the strictly lower triangular part of A + is not referenced. If UPLO = 'L', the leading n by n lower + triangular part of A contains the lower triangular part of + the matrix A, and the strictly upper triangular part of A is + not referenced. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(N,1). + + WORK (workspace) REAL array, dimension (LWORK), + where LWORK >= N when NORM = 'I' or '1' or 'O'; otherwise, + WORK is not referenced. + + ===================================================================== +*/ + + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --work; + + /* Function Body */ + if (*n == 0) { + value = 0.f; + } else if (lsame_(norm, "M")) { + +/* Find max(abs(A(i,j))). */ + + value = 0.f; + if (lsame_(uplo, "U")) { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = j; + for (i__ = 1; i__ <= i__2; ++i__) { +/* Computing MAX */ + r__2 = value, r__3 = (r__1 = a[i__ + j * a_dim1], dabs( + r__1)); + value = dmax(r__2,r__3); +/* L10: */ + } +/* L20: */ + } + } else { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = *n; + for (i__ = j; i__ <= i__2; ++i__) { +/* Computing MAX */ + r__2 = value, r__3 = (r__1 = a[i__ + j * a_dim1], dabs( + r__1)); + value = dmax(r__2,r__3); +/* L30: */ + } +/* L40: */ + } + } + } else if (lsame_(norm, "I") || lsame_(norm, "O") || *(unsigned char *)norm == '1') { + +/* Find normI(A) ( = norm1(A), since A is symmetric). */ + + value = 0.f; + if (lsame_(uplo, "U")) { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = 0.f; + i__2 = j - 1; + for (i__ = 1; i__ <= i__2; ++i__) { + absa = (r__1 = a[i__ + j * a_dim1], dabs(r__1)); + sum += absa; + work[i__] += absa; +/* L50: */ + } + work[j] = sum + (r__1 = a[j + j * a_dim1], dabs(r__1)); +/* L60: */ + } + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { +/* Computing MAX */ + r__1 = value, r__2 = work[i__]; + value = dmax(r__1,r__2); +/* L70: */ + } + } else { + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + work[i__] = 0.f; +/* L80: */ + } + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = work[j] + (r__1 = a[j + j * a_dim1], dabs(r__1)); + i__2 = *n; + for (i__ = j + 1; i__ <= i__2; ++i__) { + absa = (r__1 = a[i__ + j * a_dim1], dabs(r__1)); + sum += absa; + work[i__] += absa; +/* L90: */ + } + value = dmax(value,sum); +/* L100: */ + } + } + } else if (lsame_(norm, "F") || lsame_(norm, "E")) { + +/* Find normF(A). */ + + scale = 0.f; + sum = 1.f; + if (lsame_(uplo, "U")) { + i__1 = *n; + for (j = 2; j <= i__1; ++j) { + i__2 = j - 1; + slassq_(&i__2, &a[j * a_dim1 + 1], &c__1, &scale, &sum); +/* L110: */ + } + } else { + i__1 = *n - 1; + for (j = 1; j <= i__1; ++j) { + i__2 = *n - j; + slassq_(&i__2, &a[j + 1 + j * a_dim1], &c__1, &scale, &sum); +/* L120: */ + } + } + sum *= 2; + i__1 = *lda + 1; + slassq_(n, &a[a_offset], &i__1, &scale, &sum); + value = scale * sqrt(sum); + } + + ret_val = value; + return ret_val; + +/* End of SLANSY */ + +} /* slansy_ */ + +/* Subroutine */ int slanv2_(real *a, real *b, real *c__, real *d__, real * + rt1r, real *rt1i, real *rt2r, real *rt2i, real *cs, real *sn) +{ + /* System generated locals */ + real r__1, r__2; + + /* Builtin functions */ + double r_sign(real *, real *), sqrt(doublereal); + + /* Local variables */ + static real p, z__, aa, bb, cc, dd, cs1, sn1, sab, sac, eps, tau, temp, + scale, bcmax, bcmis, sigma; + extern doublereal slapy2_(real *, real *), slamch_(char *); + + +/* + -- LAPACK driver routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SLANV2 computes the Schur factorization of a real 2-by-2 nonsymmetric + matrix in standard form: + + [ A B ] = [ CS -SN ] [ AA BB ] [ CS SN ] + [ C D ] [ SN CS ] [ CC DD ] [-SN CS ] + + where either + 1) CC = 0 so that AA and DD are real eigenvalues of the matrix, or + 2) AA = DD and BB*CC < 0, so that AA + or - sqrt(BB*CC) are complex + conjugate eigenvalues. + + Arguments + ========= + + A (input/output) REAL + B (input/output) REAL + C (input/output) REAL + D (input/output) REAL + On entry, the elements of the input matrix. + On exit, they are overwritten by the elements of the + standardised Schur form. + + RT1R (output) REAL + RT1I (output) REAL + RT2R (output) REAL + RT2I (output) REAL + The real and imaginary parts of the eigenvalues. If the + eigenvalues are a complex conjugate pair, RT1I > 0. + + CS (output) REAL + SN (output) REAL + Parameters of the rotation matrix. + + Further Details + =============== + + Modified by V. Sima, Research Institute for Informatics, Bucharest, + Romania, to reduce the risk of cancellation errors, + when computing real eigenvalues, and to ensure, if possible, that + abs(RT1R) >= abs(RT2R). + + ===================================================================== +*/ + + + eps = slamch_("P"); + if (*c__ == 0.f) { + *cs = 1.f; + *sn = 0.f; + goto L10; + + } else if (*b == 0.f) { + +/* Swap rows and columns */ + + *cs = 0.f; + *sn = 1.f; + temp = *d__; + *d__ = *a; + *a = temp; + *b = -(*c__); + *c__ = 0.f; + goto L10; + } else if (*a - *d__ == 0.f && r_sign(&c_b15, b) != r_sign(&c_b15, c__)) { + *cs = 1.f; + *sn = 0.f; + goto L10; + } else { + + temp = *a - *d__; + p = temp * .5f; +/* Computing MAX */ + r__1 = dabs(*b), r__2 = dabs(*c__); + bcmax = dmax(r__1,r__2); +/* Computing MIN */ + r__1 = dabs(*b), r__2 = dabs(*c__); + bcmis = dmin(r__1,r__2) * r_sign(&c_b15, b) * r_sign(&c_b15, c__); +/* Computing MAX */ + r__1 = dabs(p); + scale = dmax(r__1,bcmax); + z__ = p / scale * p + bcmax / scale * bcmis; + +/* + If Z is of the order of the machine accuracy, postpone the + decision on the nature of eigenvalues +*/ + + if (z__ >= eps * 4.f) { + +/* Real eigenvalues. Compute A and D. */ + + r__1 = sqrt(scale) * sqrt(z__); + z__ = p + r_sign(&r__1, &p); + *a = *d__ + z__; + *d__ -= bcmax / z__ * bcmis; + +/* Compute B and the rotation matrix */ + + tau = slapy2_(c__, &z__); + *cs = z__ / tau; + *sn = *c__ / tau; + *b -= *c__; + *c__ = 0.f; + } else { + +/* + Complex eigenvalues, or real (almost) equal eigenvalues. + Make diagonal elements equal. +*/ + + sigma = *b + *c__; + tau = slapy2_(&sigma, &temp); + *cs = sqrt((dabs(sigma) / tau + 1.f) * .5f); + *sn = -(p / (tau * *cs)) * r_sign(&c_b15, &sigma); + +/* + Compute [ AA BB ] = [ A B ] [ CS -SN ] + [ CC DD ] [ C D ] [ SN CS ] +*/ + + aa = *a * *cs + *b * *sn; + bb = -(*a) * *sn + *b * *cs; + cc = *c__ * *cs + *d__ * *sn; + dd = -(*c__) * *sn + *d__ * *cs; + +/* + Compute [ A B ] = [ CS SN ] [ AA BB ] + [ C D ] [-SN CS ] [ CC DD ] +*/ + + *a = aa * *cs + cc * *sn; + *b = bb * *cs + dd * *sn; + *c__ = -aa * *sn + cc * *cs; + *d__ = -bb * *sn + dd * *cs; + + temp = (*a + *d__) * .5f; + *a = temp; + *d__ = temp; + + if (*c__ != 0.f) { + if (*b != 0.f) { + if (r_sign(&c_b15, b) == r_sign(&c_b15, c__)) { + +/* Real eigenvalues: reduce to upper triangular form */ + + sab = sqrt((dabs(*b))); + sac = sqrt((dabs(*c__))); + r__1 = sab * sac; + p = r_sign(&r__1, c__); + tau = 1.f / sqrt((r__1 = *b + *c__, dabs(r__1))); + *a = temp + p; + *d__ = temp - p; + *b -= *c__; + *c__ = 0.f; + cs1 = sab * tau; + sn1 = sac * tau; + temp = *cs * cs1 - *sn * sn1; + *sn = *cs * sn1 + *sn * cs1; + *cs = temp; + } + } else { + *b = -(*c__); + *c__ = 0.f; + temp = *cs; + *cs = -(*sn); + *sn = temp; + } + } + } + + } + +L10: + +/* Store eigenvalues in (RT1R,RT1I) and (RT2R,RT2I). */ + + *rt1r = *a; + *rt2r = *d__; + if (*c__ == 0.f) { + *rt1i = 0.f; + *rt2i = 0.f; + } else { + *rt1i = sqrt((dabs(*b))) * sqrt((dabs(*c__))); + *rt2i = -(*rt1i); + } + return 0; + +/* End of SLANV2 */ + +} /* slanv2_ */ + +doublereal slapy2_(real *x, real *y) +{ + /* System generated locals */ + real ret_val, r__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real w, z__, xabs, yabs; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary + overflow. + + Arguments + ========= + + X (input) REAL + Y (input) REAL + X and Y specify the values x and y. + + ===================================================================== +*/ + + + xabs = dabs(*x); + yabs = dabs(*y); + w = dmax(xabs,yabs); + z__ = dmin(xabs,yabs); + if (z__ == 0.f) { + ret_val = w; + } else { +/* Computing 2nd power */ + r__1 = z__ / w; + ret_val = w * sqrt(r__1 * r__1 + 1.f); + } + return ret_val; + +/* End of SLAPY2 */ + +} /* slapy2_ */ + +doublereal slapy3_(real *x, real *y, real *z__) +{ + /* System generated locals */ + real ret_val, r__1, r__2, r__3; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real w, xabs, yabs, zabs; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLAPY3 returns sqrt(x**2+y**2+z**2), taking care not to cause + unnecessary overflow. + + Arguments + ========= + + X (input) REAL + Y (input) REAL + Z (input) REAL + X, Y and Z specify the values x, y and z. + + ===================================================================== +*/ + + + xabs = dabs(*x); + yabs = dabs(*y); + zabs = dabs(*z__); +/* Computing MAX */ + r__1 = max(xabs,yabs); + w = dmax(r__1,zabs); + if (w == 0.f) { + ret_val = 0.f; + } else { +/* Computing 2nd power */ + r__1 = xabs / w; +/* Computing 2nd power */ + r__2 = yabs / w; +/* Computing 2nd power */ + r__3 = zabs / w; + ret_val = w * sqrt(r__1 * r__1 + r__2 * r__2 + r__3 * r__3); + } + return ret_val; + +/* End of SLAPY3 */ + +} /* slapy3_ */ + +/* Subroutine */ int slarf_(char *side, integer *m, integer *n, real *v, + integer *incv, real *tau, real *c__, integer *ldc, real *work) +{ + /* System generated locals */ + integer c_dim1, c_offset; + real r__1; + + /* Local variables */ + extern /* Subroutine */ int sger_(integer *, integer *, real *, real *, + integer *, real *, integer *, real *, integer *); + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sgemv_(char *, integer *, integer *, real *, + real *, integer *, real *, integer *, real *, real *, integer *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SLARF applies a real elementary reflector H to a real m by n matrix + C, from either the left or the right. H is represented in the form + + H = I - tau * v * v' + + where tau is a real scalar and v is a real vector. + + If tau = 0, then H is taken to be the unit matrix. + + Arguments + ========= + + SIDE (input) CHARACTER*1 + = 'L': form H * C + = 'R': form C * H + + M (input) INTEGER + The number of rows of the matrix C. + + N (input) INTEGER + The number of columns of the matrix C. + + V (input) REAL array, dimension + (1 + (M-1)*abs(INCV)) if SIDE = 'L' + or (1 + (N-1)*abs(INCV)) if SIDE = 'R' + The vector v in the representation of H. V is not used if + TAU = 0. + + INCV (input) INTEGER + The increment between elements of v. INCV <> 0. + + TAU (input) REAL + The value tau in the representation of H. + + C (input/output) REAL array, dimension (LDC,N) + On entry, the m by n matrix C. + On exit, C is overwritten by the matrix H * C if SIDE = 'L', + or C * H if SIDE = 'R'. + + LDC (input) INTEGER + The leading dimension of the array C. LDC >= max(1,M). + + WORK (workspace) REAL array, dimension + (N) if SIDE = 'L' + or (M) if SIDE = 'R' + + ===================================================================== +*/ + + + /* Parameter adjustments */ + --v; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + if (lsame_(side, "L")) { + +/* Form H * C */ + + if (*tau != 0.f) { + +/* w := C' * v */ + + sgemv_("Transpose", m, n, &c_b15, &c__[c_offset], ldc, &v[1], + incv, &c_b29, &work[1], &c__1); + +/* C := C - v * w' */ + + r__1 = -(*tau); + sger_(m, n, &r__1, &v[1], incv, &work[1], &c__1, &c__[c_offset], + ldc); + } + } else { + +/* Form C * H */ + + if (*tau != 0.f) { + +/* w := C * v */ + + sgemv_("No transpose", m, n, &c_b15, &c__[c_offset], ldc, &v[1], + incv, &c_b29, &work[1], &c__1); + +/* C := C - w * v' */ + + r__1 = -(*tau); + sger_(m, n, &r__1, &work[1], &c__1, &v[1], incv, &c__[c_offset], + ldc); + } + } + return 0; + +/* End of SLARF */ + +} /* slarf_ */ + +/* Subroutine */ int slarfb_(char *side, char *trans, char *direct, char * + storev, integer *m, integer *n, integer *k, real *v, integer *ldv, + real *t, integer *ldt, real *c__, integer *ldc, real *work, integer * + ldwork) +{ + /* System generated locals */ + integer c_dim1, c_offset, t_dim1, t_offset, v_dim1, v_offset, work_dim1, + work_offset, i__1, i__2; + + /* Local variables */ + static integer i__, j; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *), scopy_(integer *, real *, + integer *, real *, integer *), strmm_(char *, char *, char *, + char *, integer *, integer *, real *, real *, integer *, real *, + integer *); + static char transt[1]; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SLARFB applies a real block reflector H or its transpose H' to a + real m by n matrix C, from either the left or the right. + + Arguments + ========= + + SIDE (input) CHARACTER*1 + = 'L': apply H or H' from the Left + = 'R': apply H or H' from the Right + + TRANS (input) CHARACTER*1 + = 'N': apply H (No transpose) + = 'T': apply H' (Transpose) + + DIRECT (input) CHARACTER*1 + Indicates how H is formed from a product of elementary + reflectors + = 'F': H = H(1) H(2) . . . H(k) (Forward) + = 'B': H = H(k) . . . H(2) H(1) (Backward) + + STOREV (input) CHARACTER*1 + Indicates how the vectors which define the elementary + reflectors are stored: + = 'C': Columnwise + = 'R': Rowwise + + M (input) INTEGER + The number of rows of the matrix C. + + N (input) INTEGER + The number of columns of the matrix C. + + K (input) INTEGER + The order of the matrix T (= the number of elementary + reflectors whose product defines the block reflector). + + V (input) REAL array, dimension + (LDV,K) if STOREV = 'C' + (LDV,M) if STOREV = 'R' and SIDE = 'L' + (LDV,N) if STOREV = 'R' and SIDE = 'R' + The matrix V. See further details. + + LDV (input) INTEGER + The leading dimension of the array V. + If STOREV = 'C' and SIDE = 'L', LDV >= max(1,M); + if STOREV = 'C' and SIDE = 'R', LDV >= max(1,N); + if STOREV = 'R', LDV >= K. + + T (input) REAL array, dimension (LDT,K) + The triangular k by k matrix T in the representation of the + block reflector. + + LDT (input) INTEGER + The leading dimension of the array T. LDT >= K. + + C (input/output) REAL array, dimension (LDC,N) + On entry, the m by n matrix C. + On exit, C is overwritten by H*C or H'*C or C*H or C*H'. + + LDC (input) INTEGER + The leading dimension of the array C. LDA >= max(1,M). + + WORK (workspace) REAL array, dimension (LDWORK,K) + + LDWORK (input) INTEGER + The leading dimension of the array WORK. + If SIDE = 'L', LDWORK >= max(1,N); + if SIDE = 'R', LDWORK >= max(1,M). + + ===================================================================== + + + Quick return if possible +*/ + + /* Parameter adjustments */ + v_dim1 = *ldv; + v_offset = 1 + v_dim1; + v -= v_offset; + t_dim1 = *ldt; + t_offset = 1 + t_dim1; + t -= t_offset; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + work_dim1 = *ldwork; + work_offset = 1 + work_dim1; + work -= work_offset; + + /* Function Body */ + if (*m <= 0 || *n <= 0) { + return 0; + } + + if (lsame_(trans, "N")) { + *(unsigned char *)transt = 'T'; + } else { + *(unsigned char *)transt = 'N'; + } + + if (lsame_(storev, "C")) { + + if (lsame_(direct, "F")) { + +/* + Let V = ( V1 ) (first K rows) + ( V2 ) + where V1 is unit lower triangular. +*/ + + if (lsame_(side, "L")) { + +/* + Form H * C or H' * C where C = ( C1 ) + ( C2 ) + + W := C' * V = (C1'*V1 + C2'*V2) (stored in WORK) + + W := C1' +*/ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + scopy_(n, &c__[j + c_dim1], ldc, &work[j * work_dim1 + 1], + &c__1); +/* L10: */ + } + +/* W := W * V1 */ + + strmm_("Right", "Lower", "No transpose", "Unit", n, k, &c_b15, + &v[v_offset], ldv, &work[work_offset], ldwork); + if (*m > *k) { + +/* W := W + C2'*V2 */ + + i__1 = *m - *k; + sgemm_("Transpose", "No transpose", n, k, &i__1, &c_b15, & + c__[*k + 1 + c_dim1], ldc, &v[*k + 1 + v_dim1], + ldv, &c_b15, &work[work_offset], ldwork); + } + +/* W := W * T' or W * T */ + + strmm_("Right", "Upper", transt, "Non-unit", n, k, &c_b15, &t[ + t_offset], ldt, &work[work_offset], ldwork); + +/* C := C - V * W' */ + + if (*m > *k) { + +/* C2 := C2 - V2 * W' */ + + i__1 = *m - *k; + sgemm_("No transpose", "Transpose", &i__1, n, k, &c_b151, + &v[*k + 1 + v_dim1], ldv, &work[work_offset], + ldwork, &c_b15, &c__[*k + 1 + c_dim1], ldc); + } + +/* W := W * V1' */ + + strmm_("Right", "Lower", "Transpose", "Unit", n, k, &c_b15, & + v[v_offset], ldv, &work[work_offset], ldwork); + +/* C1 := C1 - W' */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = *n; + for (i__ = 1; i__ <= i__2; ++i__) { + c__[j + i__ * c_dim1] -= work[i__ + j * work_dim1]; +/* L20: */ + } +/* L30: */ + } + + } else if (lsame_(side, "R")) { + +/* + Form C * H or C * H' where C = ( C1 C2 ) + + W := C * V = (C1*V1 + C2*V2) (stored in WORK) + + W := C1 +*/ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + scopy_(m, &c__[j * c_dim1 + 1], &c__1, &work[j * + work_dim1 + 1], &c__1); +/* L40: */ + } + +/* W := W * V1 */ + + strmm_("Right", "Lower", "No transpose", "Unit", m, k, &c_b15, + &v[v_offset], ldv, &work[work_offset], ldwork); + if (*n > *k) { + +/* W := W + C2 * V2 */ + + i__1 = *n - *k; + sgemm_("No transpose", "No transpose", m, k, &i__1, & + c_b15, &c__[(*k + 1) * c_dim1 + 1], ldc, &v[*k + + 1 + v_dim1], ldv, &c_b15, &work[work_offset], + ldwork); + } + +/* W := W * T or W * T' */ + + strmm_("Right", "Upper", trans, "Non-unit", m, k, &c_b15, &t[ + t_offset], ldt, &work[work_offset], ldwork); + +/* C := C - W * V' */ + + if (*n > *k) { + +/* C2 := C2 - W * V2' */ + + i__1 = *n - *k; + sgemm_("No transpose", "Transpose", m, &i__1, k, &c_b151, + &work[work_offset], ldwork, &v[*k + 1 + v_dim1], + ldv, &c_b15, &c__[(*k + 1) * c_dim1 + 1], ldc); + } + +/* W := W * V1' */ + + strmm_("Right", "Lower", "Transpose", "Unit", m, k, &c_b15, & + v[v_offset], ldv, &work[work_offset], ldwork); + +/* C1 := C1 - W */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + c__[i__ + j * c_dim1] -= work[i__ + j * work_dim1]; +/* L50: */ + } +/* L60: */ + } + } + + } else { + +/* + Let V = ( V1 ) + ( V2 ) (last K rows) + where V2 is unit upper triangular. +*/ + + if (lsame_(side, "L")) { + +/* + Form H * C or H' * C where C = ( C1 ) + ( C2 ) + + W := C' * V = (C1'*V1 + C2'*V2) (stored in WORK) + + W := C2' +*/ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + scopy_(n, &c__[*m - *k + j + c_dim1], ldc, &work[j * + work_dim1 + 1], &c__1); +/* L70: */ + } + +/* W := W * V2 */ + + strmm_("Right", "Upper", "No transpose", "Unit", n, k, &c_b15, + &v[*m - *k + 1 + v_dim1], ldv, &work[work_offset], + ldwork); + if (*m > *k) { + +/* W := W + C1'*V1 */ + + i__1 = *m - *k; + sgemm_("Transpose", "No transpose", n, k, &i__1, &c_b15, & + c__[c_offset], ldc, &v[v_offset], ldv, &c_b15, & + work[work_offset], ldwork); + } + +/* W := W * T' or W * T */ + + strmm_("Right", "Lower", transt, "Non-unit", n, k, &c_b15, &t[ + t_offset], ldt, &work[work_offset], ldwork); + +/* C := C - V * W' */ + + if (*m > *k) { + +/* C1 := C1 - V1 * W' */ + + i__1 = *m - *k; + sgemm_("No transpose", "Transpose", &i__1, n, k, &c_b151, + &v[v_offset], ldv, &work[work_offset], ldwork, & + c_b15, &c__[c_offset], ldc) + ; + } + +/* W := W * V2' */ + + strmm_("Right", "Upper", "Transpose", "Unit", n, k, &c_b15, & + v[*m - *k + 1 + v_dim1], ldv, &work[work_offset], + ldwork); + +/* C2 := C2 - W' */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = *n; + for (i__ = 1; i__ <= i__2; ++i__) { + c__[*m - *k + j + i__ * c_dim1] -= work[i__ + j * + work_dim1]; +/* L80: */ + } +/* L90: */ + } + + } else if (lsame_(side, "R")) { + +/* + Form C * H or C * H' where C = ( C1 C2 ) + + W := C * V = (C1*V1 + C2*V2) (stored in WORK) + + W := C2 +*/ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + scopy_(m, &c__[(*n - *k + j) * c_dim1 + 1], &c__1, &work[ + j * work_dim1 + 1], &c__1); +/* L100: */ + } + +/* W := W * V2 */ + + strmm_("Right", "Upper", "No transpose", "Unit", m, k, &c_b15, + &v[*n - *k + 1 + v_dim1], ldv, &work[work_offset], + ldwork); + if (*n > *k) { + +/* W := W + C1 * V1 */ + + i__1 = *n - *k; + sgemm_("No transpose", "No transpose", m, k, &i__1, & + c_b15, &c__[c_offset], ldc, &v[v_offset], ldv, & + c_b15, &work[work_offset], ldwork); + } + +/* W := W * T or W * T' */ + + strmm_("Right", "Lower", trans, "Non-unit", m, k, &c_b15, &t[ + t_offset], ldt, &work[work_offset], ldwork); + +/* C := C - W * V' */ + + if (*n > *k) { + +/* C1 := C1 - W * V1' */ + + i__1 = *n - *k; + sgemm_("No transpose", "Transpose", m, &i__1, k, &c_b151, + &work[work_offset], ldwork, &v[v_offset], ldv, & + c_b15, &c__[c_offset], ldc) + ; + } + +/* W := W * V2' */ + + strmm_("Right", "Upper", "Transpose", "Unit", m, k, &c_b15, & + v[*n - *k + 1 + v_dim1], ldv, &work[work_offset], + ldwork); + +/* C2 := C2 - W */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + c__[i__ + (*n - *k + j) * c_dim1] -= work[i__ + j * + work_dim1]; +/* L110: */ + } +/* L120: */ + } + } + } + + } else if (lsame_(storev, "R")) { + + if (lsame_(direct, "F")) { + +/* + Let V = ( V1 V2 ) (V1: first K columns) + where V1 is unit upper triangular. +*/ + + if (lsame_(side, "L")) { + +/* + Form H * C or H' * C where C = ( C1 ) + ( C2 ) + + W := C' * V' = (C1'*V1' + C2'*V2') (stored in WORK) + + W := C1' +*/ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + scopy_(n, &c__[j + c_dim1], ldc, &work[j * work_dim1 + 1], + &c__1); +/* L130: */ + } + +/* W := W * V1' */ + + strmm_("Right", "Upper", "Transpose", "Unit", n, k, &c_b15, & + v[v_offset], ldv, &work[work_offset], ldwork); + if (*m > *k) { + +/* W := W + C2'*V2' */ + + i__1 = *m - *k; + sgemm_("Transpose", "Transpose", n, k, &i__1, &c_b15, & + c__[*k + 1 + c_dim1], ldc, &v[(*k + 1) * v_dim1 + + 1], ldv, &c_b15, &work[work_offset], ldwork); + } + +/* W := W * T' or W * T */ + + strmm_("Right", "Upper", transt, "Non-unit", n, k, &c_b15, &t[ + t_offset], ldt, &work[work_offset], ldwork); + +/* C := C - V' * W' */ + + if (*m > *k) { + +/* C2 := C2 - V2' * W' */ + + i__1 = *m - *k; + sgemm_("Transpose", "Transpose", &i__1, n, k, &c_b151, &v[ + (*k + 1) * v_dim1 + 1], ldv, &work[work_offset], + ldwork, &c_b15, &c__[*k + 1 + c_dim1], ldc); + } + +/* W := W * V1 */ + + strmm_("Right", "Upper", "No transpose", "Unit", n, k, &c_b15, + &v[v_offset], ldv, &work[work_offset], ldwork); + +/* C1 := C1 - W' */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = *n; + for (i__ = 1; i__ <= i__2; ++i__) { + c__[j + i__ * c_dim1] -= work[i__ + j * work_dim1]; +/* L140: */ + } +/* L150: */ + } + + } else if (lsame_(side, "R")) { + +/* + Form C * H or C * H' where C = ( C1 C2 ) + + W := C * V' = (C1*V1' + C2*V2') (stored in WORK) + + W := C1 +*/ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + scopy_(m, &c__[j * c_dim1 + 1], &c__1, &work[j * + work_dim1 + 1], &c__1); +/* L160: */ + } + +/* W := W * V1' */ + + strmm_("Right", "Upper", "Transpose", "Unit", m, k, &c_b15, & + v[v_offset], ldv, &work[work_offset], ldwork); + if (*n > *k) { + +/* W := W + C2 * V2' */ + + i__1 = *n - *k; + sgemm_("No transpose", "Transpose", m, k, &i__1, &c_b15, & + c__[(*k + 1) * c_dim1 + 1], ldc, &v[(*k + 1) * + v_dim1 + 1], ldv, &c_b15, &work[work_offset], + ldwork); + } + +/* W := W * T or W * T' */ + + strmm_("Right", "Upper", trans, "Non-unit", m, k, &c_b15, &t[ + t_offset], ldt, &work[work_offset], ldwork); + +/* C := C - W * V */ + + if (*n > *k) { + +/* C2 := C2 - W * V2 */ + + i__1 = *n - *k; + sgemm_("No transpose", "No transpose", m, &i__1, k, & + c_b151, &work[work_offset], ldwork, &v[(*k + 1) * + v_dim1 + 1], ldv, &c_b15, &c__[(*k + 1) * c_dim1 + + 1], ldc); + } + +/* W := W * V1 */ + + strmm_("Right", "Upper", "No transpose", "Unit", m, k, &c_b15, + &v[v_offset], ldv, &work[work_offset], ldwork); + +/* C1 := C1 - W */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + c__[i__ + j * c_dim1] -= work[i__ + j * work_dim1]; +/* L170: */ + } +/* L180: */ + } + + } + + } else { + +/* + Let V = ( V1 V2 ) (V2: last K columns) + where V2 is unit lower triangular. +*/ + + if (lsame_(side, "L")) { + +/* + Form H * C or H' * C where C = ( C1 ) + ( C2 ) + + W := C' * V' = (C1'*V1' + C2'*V2') (stored in WORK) + + W := C2' +*/ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + scopy_(n, &c__[*m - *k + j + c_dim1], ldc, &work[j * + work_dim1 + 1], &c__1); +/* L190: */ + } + +/* W := W * V2' */ + + strmm_("Right", "Lower", "Transpose", "Unit", n, k, &c_b15, & + v[(*m - *k + 1) * v_dim1 + 1], ldv, &work[work_offset] + , ldwork); + if (*m > *k) { + +/* W := W + C1'*V1' */ + + i__1 = *m - *k; + sgemm_("Transpose", "Transpose", n, k, &i__1, &c_b15, & + c__[c_offset], ldc, &v[v_offset], ldv, &c_b15, & + work[work_offset], ldwork); + } + +/* W := W * T' or W * T */ + + strmm_("Right", "Lower", transt, "Non-unit", n, k, &c_b15, &t[ + t_offset], ldt, &work[work_offset], ldwork); + +/* C := C - V' * W' */ + + if (*m > *k) { + +/* C1 := C1 - V1' * W' */ + + i__1 = *m - *k; + sgemm_("Transpose", "Transpose", &i__1, n, k, &c_b151, &v[ + v_offset], ldv, &work[work_offset], ldwork, & + c_b15, &c__[c_offset], ldc); + } + +/* W := W * V2 */ + + strmm_("Right", "Lower", "No transpose", "Unit", n, k, &c_b15, + &v[(*m - *k + 1) * v_dim1 + 1], ldv, &work[ + work_offset], ldwork); + +/* C2 := C2 - W' */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = *n; + for (i__ = 1; i__ <= i__2; ++i__) { + c__[*m - *k + j + i__ * c_dim1] -= work[i__ + j * + work_dim1]; +/* L200: */ + } +/* L210: */ + } + + } else if (lsame_(side, "R")) { + +/* + Form C * H or C * H' where C = ( C1 C2 ) + + W := C * V' = (C1*V1' + C2*V2') (stored in WORK) + + W := C2 +*/ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + scopy_(m, &c__[(*n - *k + j) * c_dim1 + 1], &c__1, &work[ + j * work_dim1 + 1], &c__1); +/* L220: */ + } + +/* W := W * V2' */ + + strmm_("Right", "Lower", "Transpose", "Unit", m, k, &c_b15, & + v[(*n - *k + 1) * v_dim1 + 1], ldv, &work[work_offset] + , ldwork); + if (*n > *k) { + +/* W := W + C1 * V1' */ + + i__1 = *n - *k; + sgemm_("No transpose", "Transpose", m, k, &i__1, &c_b15, & + c__[c_offset], ldc, &v[v_offset], ldv, &c_b15, & + work[work_offset], ldwork); + } + +/* W := W * T or W * T' */ + + strmm_("Right", "Lower", trans, "Non-unit", m, k, &c_b15, &t[ + t_offset], ldt, &work[work_offset], ldwork); + +/* C := C - W * V */ + + if (*n > *k) { + +/* C1 := C1 - W * V1 */ + + i__1 = *n - *k; + sgemm_("No transpose", "No transpose", m, &i__1, k, & + c_b151, &work[work_offset], ldwork, &v[v_offset], + ldv, &c_b15, &c__[c_offset], ldc); + } + +/* W := W * V2 */ + + strmm_("Right", "Lower", "No transpose", "Unit", m, k, &c_b15, + &v[(*n - *k + 1) * v_dim1 + 1], ldv, &work[ + work_offset], ldwork); + +/* C1 := C1 - W */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + c__[i__ + (*n - *k + j) * c_dim1] -= work[i__ + j * + work_dim1]; +/* L230: */ + } +/* L240: */ + } + + } + + } + } + + return 0; + +/* End of SLARFB */ + +} /* slarfb_ */ + +/* Subroutine */ int slarfg_(integer *n, real *alpha, real *x, integer *incx, + real *tau) +{ + /* System generated locals */ + integer i__1; + real r__1; + + /* Builtin functions */ + double r_sign(real *, real *); + + /* Local variables */ + static integer j, knt; + static real beta; + extern doublereal snrm2_(integer *, real *, integer *); + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *); + static real xnorm; + extern doublereal slapy2_(real *, real *), slamch_(char *); + static real safmin, rsafmn; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + September 30, 1994 + + + Purpose + ======= + + SLARFG generates a real elementary reflector H of order n, such + that + + H * ( alpha ) = ( beta ), H' * H = I. + ( x ) ( 0 ) + + where alpha and beta are scalars, and x is an (n-1)-element real + vector. H is represented in the form + + H = I - tau * ( 1 ) * ( 1 v' ) , + ( v ) + + where tau is a real scalar and v is a real (n-1)-element + vector. + + If the elements of x are all zero, then tau = 0 and H is taken to be + the unit matrix. + + Otherwise 1 <= tau <= 2. + + Arguments + ========= + + N (input) INTEGER + The order of the elementary reflector. + + ALPHA (input/output) REAL + On entry, the value alpha. + On exit, it is overwritten with the value beta. + + X (input/output) REAL array, dimension + (1+(N-2)*abs(INCX)) + On entry, the vector x. + On exit, it is overwritten with the vector v. + + INCX (input) INTEGER + The increment between elements of X. INCX > 0. + + TAU (output) REAL + The value tau. + + ===================================================================== +*/ + + + /* Parameter adjustments */ + --x; + + /* Function Body */ + if (*n <= 1) { + *tau = 0.f; + return 0; + } + + i__1 = *n - 1; + xnorm = snrm2_(&i__1, &x[1], incx); + + if (xnorm == 0.f) { + +/* H = I */ + + *tau = 0.f; + } else { + +/* general case */ + + r__1 = slapy2_(alpha, &xnorm); + beta = -r_sign(&r__1, alpha); + safmin = slamch_("S") / slamch_("E"); + if (dabs(beta) < safmin) { + +/* XNORM, BETA may be inaccurate; scale X and recompute them */ + + rsafmn = 1.f / safmin; + knt = 0; +L10: + ++knt; + i__1 = *n - 1; + sscal_(&i__1, &rsafmn, &x[1], incx); + beta *= rsafmn; + *alpha *= rsafmn; + if (dabs(beta) < safmin) { + goto L10; + } + +/* New BETA is at most 1, at least SAFMIN */ + + i__1 = *n - 1; + xnorm = snrm2_(&i__1, &x[1], incx); + r__1 = slapy2_(alpha, &xnorm); + beta = -r_sign(&r__1, alpha); + *tau = (beta - *alpha) / beta; + i__1 = *n - 1; + r__1 = 1.f / (*alpha - beta); + sscal_(&i__1, &r__1, &x[1], incx); + +/* If ALPHA is subnormal, it may lose relative accuracy */ + + *alpha = beta; + i__1 = knt; + for (j = 1; j <= i__1; ++j) { + *alpha *= safmin; +/* L20: */ + } + } else { + *tau = (beta - *alpha) / beta; + i__1 = *n - 1; + r__1 = 1.f / (*alpha - beta); + sscal_(&i__1, &r__1, &x[1], incx); + *alpha = beta; + } + } + + return 0; + +/* End of SLARFG */ + +} /* slarfg_ */ + +/* Subroutine */ int slarft_(char *direct, char *storev, integer *n, integer * + k, real *v, integer *ldv, real *tau, real *t, integer *ldt) +{ + /* System generated locals */ + integer t_dim1, t_offset, v_dim1, v_offset, i__1, i__2, i__3; + real r__1; + + /* Local variables */ + static integer i__, j; + static real vii; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sgemv_(char *, integer *, integer *, real *, + real *, integer *, real *, integer *, real *, real *, integer *), strmv_(char *, char *, char *, integer *, real *, + integer *, real *, integer *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SLARFT forms the triangular factor T of a real block reflector H + of order n, which is defined as a product of k elementary reflectors. + + If DIRECT = 'F', H = H(1) H(2) . . . H(k) and T is upper triangular; + + If DIRECT = 'B', H = H(k) . . . H(2) H(1) and T is lower triangular. + + If STOREV = 'C', the vector which defines the elementary reflector + H(i) is stored in the i-th column of the array V, and + + H = I - V * T * V' + + If STOREV = 'R', the vector which defines the elementary reflector + H(i) is stored in the i-th row of the array V, and + + H = I - V' * T * V + + Arguments + ========= + + DIRECT (input) CHARACTER*1 + Specifies the order in which the elementary reflectors are + multiplied to form the block reflector: + = 'F': H = H(1) H(2) . . . H(k) (Forward) + = 'B': H = H(k) . . . H(2) H(1) (Backward) + + STOREV (input) CHARACTER*1 + Specifies how the vectors which define the elementary + reflectors are stored (see also Further Details): + = 'C': columnwise + = 'R': rowwise + + N (input) INTEGER + The order of the block reflector H. N >= 0. + + K (input) INTEGER + The order of the triangular factor T (= the number of + elementary reflectors). K >= 1. + + V (input/output) REAL array, dimension + (LDV,K) if STOREV = 'C' + (LDV,N) if STOREV = 'R' + The matrix V. See further details. + + LDV (input) INTEGER + The leading dimension of the array V. + If STOREV = 'C', LDV >= max(1,N); if STOREV = 'R', LDV >= K. + + TAU (input) REAL array, dimension (K) + TAU(i) must contain the scalar factor of the elementary + reflector H(i). + + T (output) REAL array, dimension (LDT,K) + The k by k triangular factor T of the block reflector. + If DIRECT = 'F', T is upper triangular; if DIRECT = 'B', T is + lower triangular. The rest of the array is not used. + + LDT (input) INTEGER + The leading dimension of the array T. LDT >= K. + + Further Details + =============== + + The shape of the matrix V and the storage of the vectors which define + the H(i) is best illustrated by the following example with n = 5 and + k = 3. The elements equal to 1 are not stored; the corresponding + array elements are modified but restored on exit. The rest of the + array is not used. + + DIRECT = 'F' and STOREV = 'C': DIRECT = 'F' and STOREV = 'R': + + V = ( 1 ) V = ( 1 v1 v1 v1 v1 ) + ( v1 1 ) ( 1 v2 v2 v2 ) + ( v1 v2 1 ) ( 1 v3 v3 ) + ( v1 v2 v3 ) + ( v1 v2 v3 ) + + DIRECT = 'B' and STOREV = 'C': DIRECT = 'B' and STOREV = 'R': + + V = ( v1 v2 v3 ) V = ( v1 v1 1 ) + ( v1 v2 v3 ) ( v2 v2 v2 1 ) + ( 1 v2 v3 ) ( v3 v3 v3 v3 1 ) + ( 1 v3 ) + ( 1 ) + + ===================================================================== + + + Quick return if possible +*/ + + /* Parameter adjustments */ + v_dim1 = *ldv; + v_offset = 1 + v_dim1; + v -= v_offset; + --tau; + t_dim1 = *ldt; + t_offset = 1 + t_dim1; + t -= t_offset; + + /* Function Body */ + if (*n == 0) { + return 0; + } + + if (lsame_(direct, "F")) { + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + if (tau[i__] == 0.f) { + +/* H(i) = I */ + + i__2 = i__; + for (j = 1; j <= i__2; ++j) { + t[j + i__ * t_dim1] = 0.f; +/* L10: */ + } + } else { + +/* general case */ + + vii = v[i__ + i__ * v_dim1]; + v[i__ + i__ * v_dim1] = 1.f; + if (lsame_(storev, "C")) { + +/* T(1:i-1,i) := - tau(i) * V(i:n,1:i-1)' * V(i:n,i) */ + + i__2 = *n - i__ + 1; + i__3 = i__ - 1; + r__1 = -tau[i__]; + sgemv_("Transpose", &i__2, &i__3, &r__1, &v[i__ + v_dim1], + ldv, &v[i__ + i__ * v_dim1], &c__1, &c_b29, &t[ + i__ * t_dim1 + 1], &c__1); + } else { + +/* T(1:i-1,i) := - tau(i) * V(1:i-1,i:n) * V(i,i:n)' */ + + i__2 = i__ - 1; + i__3 = *n - i__ + 1; + r__1 = -tau[i__]; + sgemv_("No transpose", &i__2, &i__3, &r__1, &v[i__ * + v_dim1 + 1], ldv, &v[i__ + i__ * v_dim1], ldv, & + c_b29, &t[i__ * t_dim1 + 1], &c__1); + } + v[i__ + i__ * v_dim1] = vii; + +/* T(1:i-1,i) := T(1:i-1,1:i-1) * T(1:i-1,i) */ + + i__2 = i__ - 1; + strmv_("Upper", "No transpose", "Non-unit", &i__2, &t[ + t_offset], ldt, &t[i__ * t_dim1 + 1], &c__1); + t[i__ + i__ * t_dim1] = tau[i__]; + } +/* L20: */ + } + } else { + for (i__ = *k; i__ >= 1; --i__) { + if (tau[i__] == 0.f) { + +/* H(i) = I */ + + i__1 = *k; + for (j = i__; j <= i__1; ++j) { + t[j + i__ * t_dim1] = 0.f; +/* L30: */ + } + } else { + +/* general case */ + + if (i__ < *k) { + if (lsame_(storev, "C")) { + vii = v[*n - *k + i__ + i__ * v_dim1]; + v[*n - *k + i__ + i__ * v_dim1] = 1.f; + +/* + T(i+1:k,i) := + - tau(i) * V(1:n-k+i,i+1:k)' * V(1:n-k+i,i) +*/ + + i__1 = *n - *k + i__; + i__2 = *k - i__; + r__1 = -tau[i__]; + sgemv_("Transpose", &i__1, &i__2, &r__1, &v[(i__ + 1) + * v_dim1 + 1], ldv, &v[i__ * v_dim1 + 1], & + c__1, &c_b29, &t[i__ + 1 + i__ * t_dim1], & + c__1); + v[*n - *k + i__ + i__ * v_dim1] = vii; + } else { + vii = v[i__ + (*n - *k + i__) * v_dim1]; + v[i__ + (*n - *k + i__) * v_dim1] = 1.f; + +/* + T(i+1:k,i) := + - tau(i) * V(i+1:k,1:n-k+i) * V(i,1:n-k+i)' +*/ + + i__1 = *k - i__; + i__2 = *n - *k + i__; + r__1 = -tau[i__]; + sgemv_("No transpose", &i__1, &i__2, &r__1, &v[i__ + + 1 + v_dim1], ldv, &v[i__ + v_dim1], ldv, & + c_b29, &t[i__ + 1 + i__ * t_dim1], &c__1); + v[i__ + (*n - *k + i__) * v_dim1] = vii; + } + +/* T(i+1:k,i) := T(i+1:k,i+1:k) * T(i+1:k,i) */ + + i__1 = *k - i__; + strmv_("Lower", "No transpose", "Non-unit", &i__1, &t[i__ + + 1 + (i__ + 1) * t_dim1], ldt, &t[i__ + 1 + i__ * + t_dim1], &c__1) + ; + } + t[i__ + i__ * t_dim1] = tau[i__]; + } +/* L40: */ + } + } + return 0; + +/* End of SLARFT */ + +} /* slarft_ */ + +/* Subroutine */ int slarfx_(char *side, integer *m, integer *n, real *v, + real *tau, real *c__, integer *ldc, real *work) +{ + /* System generated locals */ + integer c_dim1, c_offset, i__1; + real r__1; + + /* Local variables */ + static integer j; + static real t1, t2, t3, t4, t5, t6, t7, t8, t9, v1, v2, v3, v4, v5, v6, + v7, v8, v9, t10, v10, sum; + extern /* Subroutine */ int sger_(integer *, integer *, real *, real *, + integer *, real *, integer *, real *, integer *); + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sgemv_(char *, integer *, integer *, real *, + real *, integer *, real *, integer *, real *, real *, integer *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SLARFX applies a real elementary reflector H to a real m by n + matrix C, from either the left or the right. H is represented in the + form + + H = I - tau * v * v' + + where tau is a real scalar and v is a real vector. + + If tau = 0, then H is taken to be the unit matrix + + This version uses inline code if H has order < 11. + + Arguments + ========= + + SIDE (input) CHARACTER*1 + = 'L': form H * C + = 'R': form C * H + + M (input) INTEGER + The number of rows of the matrix C. + + N (input) INTEGER + The number of columns of the matrix C. + + V (input) REAL array, dimension (M) if SIDE = 'L' + or (N) if SIDE = 'R' + The vector v in the representation of H. + + TAU (input) REAL + The value tau in the representation of H. + + C (input/output) REAL array, dimension (LDC,N) + On entry, the m by n matrix C. + On exit, C is overwritten by the matrix H * C if SIDE = 'L', + or C * H if SIDE = 'R'. + + LDC (input) INTEGER + The leading dimension of the array C. LDA >= (1,M). + + WORK (workspace) REAL array, dimension + (N) if SIDE = 'L' + or (M) if SIDE = 'R' + WORK is not referenced if H has order < 11. + + ===================================================================== +*/ + + + /* Parameter adjustments */ + --v; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + if (*tau == 0.f) { + return 0; + } + if (lsame_(side, "L")) { + +/* Form H * C, where H has order m. */ + + switch (*m) { + case 1: goto L10; + case 2: goto L30; + case 3: goto L50; + case 4: goto L70; + case 5: goto L90; + case 6: goto L110; + case 7: goto L130; + case 8: goto L150; + case 9: goto L170; + case 10: goto L190; + } + +/* + Code for general M + + w := C'*v +*/ + + sgemv_("Transpose", m, n, &c_b15, &c__[c_offset], ldc, &v[1], &c__1, & + c_b29, &work[1], &c__1); + +/* C := C - tau * v * w' */ + + r__1 = -(*tau); + sger_(m, n, &r__1, &v[1], &c__1, &work[1], &c__1, &c__[c_offset], ldc) + ; + goto L410; +L10: + +/* Special code for 1 x 1 Householder */ + + t1 = 1.f - *tau * v[1] * v[1]; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + c__[j * c_dim1 + 1] = t1 * c__[j * c_dim1 + 1]; +/* L20: */ + } + goto L410; +L30: + +/* Special code for 2 x 2 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j * c_dim1 + 1] + v2 * c__[j * c_dim1 + 2]; + c__[j * c_dim1 + 1] -= sum * t1; + c__[j * c_dim1 + 2] -= sum * t2; +/* L40: */ + } + goto L410; +L50: + +/* Special code for 3 x 3 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j * c_dim1 + 1] + v2 * c__[j * c_dim1 + 2] + v3 * + c__[j * c_dim1 + 3]; + c__[j * c_dim1 + 1] -= sum * t1; + c__[j * c_dim1 + 2] -= sum * t2; + c__[j * c_dim1 + 3] -= sum * t3; +/* L60: */ + } + goto L410; +L70: + +/* Special code for 4 x 4 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j * c_dim1 + 1] + v2 * c__[j * c_dim1 + 2] + v3 * + c__[j * c_dim1 + 3] + v4 * c__[j * c_dim1 + 4]; + c__[j * c_dim1 + 1] -= sum * t1; + c__[j * c_dim1 + 2] -= sum * t2; + c__[j * c_dim1 + 3] -= sum * t3; + c__[j * c_dim1 + 4] -= sum * t4; +/* L80: */ + } + goto L410; +L90: + +/* Special code for 5 x 5 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j * c_dim1 + 1] + v2 * c__[j * c_dim1 + 2] + v3 * + c__[j * c_dim1 + 3] + v4 * c__[j * c_dim1 + 4] + v5 * c__[ + j * c_dim1 + 5]; + c__[j * c_dim1 + 1] -= sum * t1; + c__[j * c_dim1 + 2] -= sum * t2; + c__[j * c_dim1 + 3] -= sum * t3; + c__[j * c_dim1 + 4] -= sum * t4; + c__[j * c_dim1 + 5] -= sum * t5; +/* L100: */ + } + goto L410; +L110: + +/* Special code for 6 x 6 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + v6 = v[6]; + t6 = *tau * v6; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j * c_dim1 + 1] + v2 * c__[j * c_dim1 + 2] + v3 * + c__[j * c_dim1 + 3] + v4 * c__[j * c_dim1 + 4] + v5 * c__[ + j * c_dim1 + 5] + v6 * c__[j * c_dim1 + 6]; + c__[j * c_dim1 + 1] -= sum * t1; + c__[j * c_dim1 + 2] -= sum * t2; + c__[j * c_dim1 + 3] -= sum * t3; + c__[j * c_dim1 + 4] -= sum * t4; + c__[j * c_dim1 + 5] -= sum * t5; + c__[j * c_dim1 + 6] -= sum * t6; +/* L120: */ + } + goto L410; +L130: + +/* Special code for 7 x 7 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + v6 = v[6]; + t6 = *tau * v6; + v7 = v[7]; + t7 = *tau * v7; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j * c_dim1 + 1] + v2 * c__[j * c_dim1 + 2] + v3 * + c__[j * c_dim1 + 3] + v4 * c__[j * c_dim1 + 4] + v5 * c__[ + j * c_dim1 + 5] + v6 * c__[j * c_dim1 + 6] + v7 * c__[j * + c_dim1 + 7]; + c__[j * c_dim1 + 1] -= sum * t1; + c__[j * c_dim1 + 2] -= sum * t2; + c__[j * c_dim1 + 3] -= sum * t3; + c__[j * c_dim1 + 4] -= sum * t4; + c__[j * c_dim1 + 5] -= sum * t5; + c__[j * c_dim1 + 6] -= sum * t6; + c__[j * c_dim1 + 7] -= sum * t7; +/* L140: */ + } + goto L410; +L150: + +/* Special code for 8 x 8 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + v6 = v[6]; + t6 = *tau * v6; + v7 = v[7]; + t7 = *tau * v7; + v8 = v[8]; + t8 = *tau * v8; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j * c_dim1 + 1] + v2 * c__[j * c_dim1 + 2] + v3 * + c__[j * c_dim1 + 3] + v4 * c__[j * c_dim1 + 4] + v5 * c__[ + j * c_dim1 + 5] + v6 * c__[j * c_dim1 + 6] + v7 * c__[j * + c_dim1 + 7] + v8 * c__[j * c_dim1 + 8]; + c__[j * c_dim1 + 1] -= sum * t1; + c__[j * c_dim1 + 2] -= sum * t2; + c__[j * c_dim1 + 3] -= sum * t3; + c__[j * c_dim1 + 4] -= sum * t4; + c__[j * c_dim1 + 5] -= sum * t5; + c__[j * c_dim1 + 6] -= sum * t6; + c__[j * c_dim1 + 7] -= sum * t7; + c__[j * c_dim1 + 8] -= sum * t8; +/* L160: */ + } + goto L410; +L170: + +/* Special code for 9 x 9 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + v6 = v[6]; + t6 = *tau * v6; + v7 = v[7]; + t7 = *tau * v7; + v8 = v[8]; + t8 = *tau * v8; + v9 = v[9]; + t9 = *tau * v9; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j * c_dim1 + 1] + v2 * c__[j * c_dim1 + 2] + v3 * + c__[j * c_dim1 + 3] + v4 * c__[j * c_dim1 + 4] + v5 * c__[ + j * c_dim1 + 5] + v6 * c__[j * c_dim1 + 6] + v7 * c__[j * + c_dim1 + 7] + v8 * c__[j * c_dim1 + 8] + v9 * c__[j * + c_dim1 + 9]; + c__[j * c_dim1 + 1] -= sum * t1; + c__[j * c_dim1 + 2] -= sum * t2; + c__[j * c_dim1 + 3] -= sum * t3; + c__[j * c_dim1 + 4] -= sum * t4; + c__[j * c_dim1 + 5] -= sum * t5; + c__[j * c_dim1 + 6] -= sum * t6; + c__[j * c_dim1 + 7] -= sum * t7; + c__[j * c_dim1 + 8] -= sum * t8; + c__[j * c_dim1 + 9] -= sum * t9; +/* L180: */ + } + goto L410; +L190: + +/* Special code for 10 x 10 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + v6 = v[6]; + t6 = *tau * v6; + v7 = v[7]; + t7 = *tau * v7; + v8 = v[8]; + t8 = *tau * v8; + v9 = v[9]; + t9 = *tau * v9; + v10 = v[10]; + t10 = *tau * v10; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j * c_dim1 + 1] + v2 * c__[j * c_dim1 + 2] + v3 * + c__[j * c_dim1 + 3] + v4 * c__[j * c_dim1 + 4] + v5 * c__[ + j * c_dim1 + 5] + v6 * c__[j * c_dim1 + 6] + v7 * c__[j * + c_dim1 + 7] + v8 * c__[j * c_dim1 + 8] + v9 * c__[j * + c_dim1 + 9] + v10 * c__[j * c_dim1 + 10]; + c__[j * c_dim1 + 1] -= sum * t1; + c__[j * c_dim1 + 2] -= sum * t2; + c__[j * c_dim1 + 3] -= sum * t3; + c__[j * c_dim1 + 4] -= sum * t4; + c__[j * c_dim1 + 5] -= sum * t5; + c__[j * c_dim1 + 6] -= sum * t6; + c__[j * c_dim1 + 7] -= sum * t7; + c__[j * c_dim1 + 8] -= sum * t8; + c__[j * c_dim1 + 9] -= sum * t9; + c__[j * c_dim1 + 10] -= sum * t10; +/* L200: */ + } + goto L410; + } else { + +/* Form C * H, where H has order n. */ + + switch (*n) { + case 1: goto L210; + case 2: goto L230; + case 3: goto L250; + case 4: goto L270; + case 5: goto L290; + case 6: goto L310; + case 7: goto L330; + case 8: goto L350; + case 9: goto L370; + case 10: goto L390; + } + +/* + Code for general N + + w := C * v +*/ + + sgemv_("No transpose", m, n, &c_b15, &c__[c_offset], ldc, &v[1], & + c__1, &c_b29, &work[1], &c__1); + +/* C := C - tau * w * v' */ + + r__1 = -(*tau); + sger_(m, n, &r__1, &work[1], &c__1, &v[1], &c__1, &c__[c_offset], ldc) + ; + goto L410; +L210: + +/* Special code for 1 x 1 Householder */ + + t1 = 1.f - *tau * v[1] * v[1]; + i__1 = *m; + for (j = 1; j <= i__1; ++j) { + c__[j + c_dim1] = t1 * c__[j + c_dim1]; +/* L220: */ + } + goto L410; +L230: + +/* Special code for 2 x 2 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + i__1 = *m; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j + c_dim1] + v2 * c__[j + (c_dim1 << 1)]; + c__[j + c_dim1] -= sum * t1; + c__[j + (c_dim1 << 1)] -= sum * t2; +/* L240: */ + } + goto L410; +L250: + +/* Special code for 3 x 3 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + i__1 = *m; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j + c_dim1] + v2 * c__[j + (c_dim1 << 1)] + v3 * + c__[j + c_dim1 * 3]; + c__[j + c_dim1] -= sum * t1; + c__[j + (c_dim1 << 1)] -= sum * t2; + c__[j + c_dim1 * 3] -= sum * t3; +/* L260: */ + } + goto L410; +L270: + +/* Special code for 4 x 4 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + i__1 = *m; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j + c_dim1] + v2 * c__[j + (c_dim1 << 1)] + v3 * + c__[j + c_dim1 * 3] + v4 * c__[j + (c_dim1 << 2)]; + c__[j + c_dim1] -= sum * t1; + c__[j + (c_dim1 << 1)] -= sum * t2; + c__[j + c_dim1 * 3] -= sum * t3; + c__[j + (c_dim1 << 2)] -= sum * t4; +/* L280: */ + } + goto L410; +L290: + +/* Special code for 5 x 5 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + i__1 = *m; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j + c_dim1] + v2 * c__[j + (c_dim1 << 1)] + v3 * + c__[j + c_dim1 * 3] + v4 * c__[j + (c_dim1 << 2)] + v5 * + c__[j + c_dim1 * 5]; + c__[j + c_dim1] -= sum * t1; + c__[j + (c_dim1 << 1)] -= sum * t2; + c__[j + c_dim1 * 3] -= sum * t3; + c__[j + (c_dim1 << 2)] -= sum * t4; + c__[j + c_dim1 * 5] -= sum * t5; +/* L300: */ + } + goto L410; +L310: + +/* Special code for 6 x 6 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + v6 = v[6]; + t6 = *tau * v6; + i__1 = *m; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j + c_dim1] + v2 * c__[j + (c_dim1 << 1)] + v3 * + c__[j + c_dim1 * 3] + v4 * c__[j + (c_dim1 << 2)] + v5 * + c__[j + c_dim1 * 5] + v6 * c__[j + c_dim1 * 6]; + c__[j + c_dim1] -= sum * t1; + c__[j + (c_dim1 << 1)] -= sum * t2; + c__[j + c_dim1 * 3] -= sum * t3; + c__[j + (c_dim1 << 2)] -= sum * t4; + c__[j + c_dim1 * 5] -= sum * t5; + c__[j + c_dim1 * 6] -= sum * t6; +/* L320: */ + } + goto L410; +L330: + +/* Special code for 7 x 7 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + v6 = v[6]; + t6 = *tau * v6; + v7 = v[7]; + t7 = *tau * v7; + i__1 = *m; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j + c_dim1] + v2 * c__[j + (c_dim1 << 1)] + v3 * + c__[j + c_dim1 * 3] + v4 * c__[j + (c_dim1 << 2)] + v5 * + c__[j + c_dim1 * 5] + v6 * c__[j + c_dim1 * 6] + v7 * c__[ + j + c_dim1 * 7]; + c__[j + c_dim1] -= sum * t1; + c__[j + (c_dim1 << 1)] -= sum * t2; + c__[j + c_dim1 * 3] -= sum * t3; + c__[j + (c_dim1 << 2)] -= sum * t4; + c__[j + c_dim1 * 5] -= sum * t5; + c__[j + c_dim1 * 6] -= sum * t6; + c__[j + c_dim1 * 7] -= sum * t7; +/* L340: */ + } + goto L410; +L350: + +/* Special code for 8 x 8 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + v6 = v[6]; + t6 = *tau * v6; + v7 = v[7]; + t7 = *tau * v7; + v8 = v[8]; + t8 = *tau * v8; + i__1 = *m; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j + c_dim1] + v2 * c__[j + (c_dim1 << 1)] + v3 * + c__[j + c_dim1 * 3] + v4 * c__[j + (c_dim1 << 2)] + v5 * + c__[j + c_dim1 * 5] + v6 * c__[j + c_dim1 * 6] + v7 * c__[ + j + c_dim1 * 7] + v8 * c__[j + (c_dim1 << 3)]; + c__[j + c_dim1] -= sum * t1; + c__[j + (c_dim1 << 1)] -= sum * t2; + c__[j + c_dim1 * 3] -= sum * t3; + c__[j + (c_dim1 << 2)] -= sum * t4; + c__[j + c_dim1 * 5] -= sum * t5; + c__[j + c_dim1 * 6] -= sum * t6; + c__[j + c_dim1 * 7] -= sum * t7; + c__[j + (c_dim1 << 3)] -= sum * t8; +/* L360: */ + } + goto L410; +L370: + +/* Special code for 9 x 9 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + v6 = v[6]; + t6 = *tau * v6; + v7 = v[7]; + t7 = *tau * v7; + v8 = v[8]; + t8 = *tau * v8; + v9 = v[9]; + t9 = *tau * v9; + i__1 = *m; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j + c_dim1] + v2 * c__[j + (c_dim1 << 1)] + v3 * + c__[j + c_dim1 * 3] + v4 * c__[j + (c_dim1 << 2)] + v5 * + c__[j + c_dim1 * 5] + v6 * c__[j + c_dim1 * 6] + v7 * c__[ + j + c_dim1 * 7] + v8 * c__[j + (c_dim1 << 3)] + v9 * c__[ + j + c_dim1 * 9]; + c__[j + c_dim1] -= sum * t1; + c__[j + (c_dim1 << 1)] -= sum * t2; + c__[j + c_dim1 * 3] -= sum * t3; + c__[j + (c_dim1 << 2)] -= sum * t4; + c__[j + c_dim1 * 5] -= sum * t5; + c__[j + c_dim1 * 6] -= sum * t6; + c__[j + c_dim1 * 7] -= sum * t7; + c__[j + (c_dim1 << 3)] -= sum * t8; + c__[j + c_dim1 * 9] -= sum * t9; +/* L380: */ + } + goto L410; +L390: + +/* Special code for 10 x 10 Householder */ + + v1 = v[1]; + t1 = *tau * v1; + v2 = v[2]; + t2 = *tau * v2; + v3 = v[3]; + t3 = *tau * v3; + v4 = v[4]; + t4 = *tau * v4; + v5 = v[5]; + t5 = *tau * v5; + v6 = v[6]; + t6 = *tau * v6; + v7 = v[7]; + t7 = *tau * v7; + v8 = v[8]; + t8 = *tau * v8; + v9 = v[9]; + t9 = *tau * v9; + v10 = v[10]; + t10 = *tau * v10; + i__1 = *m; + for (j = 1; j <= i__1; ++j) { + sum = v1 * c__[j + c_dim1] + v2 * c__[j + (c_dim1 << 1)] + v3 * + c__[j + c_dim1 * 3] + v4 * c__[j + (c_dim1 << 2)] + v5 * + c__[j + c_dim1 * 5] + v6 * c__[j + c_dim1 * 6] + v7 * c__[ + j + c_dim1 * 7] + v8 * c__[j + (c_dim1 << 3)] + v9 * c__[ + j + c_dim1 * 9] + v10 * c__[j + c_dim1 * 10]; + c__[j + c_dim1] -= sum * t1; + c__[j + (c_dim1 << 1)] -= sum * t2; + c__[j + c_dim1 * 3] -= sum * t3; + c__[j + (c_dim1 << 2)] -= sum * t4; + c__[j + c_dim1 * 5] -= sum * t5; + c__[j + c_dim1 * 6] -= sum * t6; + c__[j + c_dim1 * 7] -= sum * t7; + c__[j + (c_dim1 << 3)] -= sum * t8; + c__[j + c_dim1 * 9] -= sum * t9; + c__[j + c_dim1 * 10] -= sum * t10; +/* L400: */ + } + goto L410; + } +L410: + return 0; + +/* End of SLARFX */ + +} /* slarfx_ */ + +/* Subroutine */ int slartg_(real *f, real *g, real *cs, real *sn, real *r__) +{ + /* Initialized data */ + + static logical first = TRUE_; + + /* System generated locals */ + integer i__1; + real r__1, r__2; + + /* Builtin functions */ + double log(doublereal), pow_ri(real *, integer *), sqrt(doublereal); + + /* Local variables */ + static integer i__; + static real f1, g1, eps, scale; + static integer count; + static real safmn2, safmx2; + extern doublereal slamch_(char *); + static real safmin; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + September 30, 1994 + + + Purpose + ======= + + SLARTG generate a plane rotation so that + + [ CS SN ] . [ F ] = [ R ] where CS**2 + SN**2 = 1. + [ -SN CS ] [ G ] [ 0 ] + + This is a slower, more accurate version of the BLAS1 routine SROTG, + with the following other differences: + F and G are unchanged on return. + If G=0, then CS=1 and SN=0. + If F=0 and (G .ne. 0), then CS=0 and SN=1 without doing any + floating point operations (saves work in SBDSQR when + there are zeros on the diagonal). + + If F exceeds G in magnitude, CS will be positive. + + Arguments + ========= + + F (input) REAL + The first component of vector to be rotated. + + G (input) REAL + The second component of vector to be rotated. + + CS (output) REAL + The cosine of the rotation. + + SN (output) REAL + The sine of the rotation. + + R (output) REAL + The nonzero component of the rotated vector. + + ===================================================================== +*/ + + + if (first) { + first = FALSE_; + safmin = slamch_("S"); + eps = slamch_("E"); + r__1 = slamch_("B"); + i__1 = (integer) (log(safmin / eps) / log(slamch_("B")) / + 2.f); + safmn2 = pow_ri(&r__1, &i__1); + safmx2 = 1.f / safmn2; + } + if (*g == 0.f) { + *cs = 1.f; + *sn = 0.f; + *r__ = *f; + } else if (*f == 0.f) { + *cs = 0.f; + *sn = 1.f; + *r__ = *g; + } else { + f1 = *f; + g1 = *g; +/* Computing MAX */ + r__1 = dabs(f1), r__2 = dabs(g1); + scale = dmax(r__1,r__2); + if (scale >= safmx2) { + count = 0; +L10: + ++count; + f1 *= safmn2; + g1 *= safmn2; +/* Computing MAX */ + r__1 = dabs(f1), r__2 = dabs(g1); + scale = dmax(r__1,r__2); + if (scale >= safmx2) { + goto L10; + } +/* Computing 2nd power */ + r__1 = f1; +/* Computing 2nd power */ + r__2 = g1; + *r__ = sqrt(r__1 * r__1 + r__2 * r__2); + *cs = f1 / *r__; + *sn = g1 / *r__; + i__1 = count; + for (i__ = 1; i__ <= i__1; ++i__) { + *r__ *= safmx2; +/* L20: */ + } + } else if (scale <= safmn2) { + count = 0; +L30: + ++count; + f1 *= safmx2; + g1 *= safmx2; +/* Computing MAX */ + r__1 = dabs(f1), r__2 = dabs(g1); + scale = dmax(r__1,r__2); + if (scale <= safmn2) { + goto L30; + } +/* Computing 2nd power */ + r__1 = f1; +/* Computing 2nd power */ + r__2 = g1; + *r__ = sqrt(r__1 * r__1 + r__2 * r__2); + *cs = f1 / *r__; + *sn = g1 / *r__; + i__1 = count; + for (i__ = 1; i__ <= i__1; ++i__) { + *r__ *= safmn2; +/* L40: */ + } + } else { +/* Computing 2nd power */ + r__1 = f1; +/* Computing 2nd power */ + r__2 = g1; + *r__ = sqrt(r__1 * r__1 + r__2 * r__2); + *cs = f1 / *r__; + *sn = g1 / *r__; + } + if (dabs(*f) > dabs(*g) && *cs < 0.f) { + *cs = -(*cs); + *sn = -(*sn); + *r__ = -(*r__); + } + } + return 0; + +/* End of SLARTG */ + +} /* slartg_ */ + +/* Subroutine */ int slas2_(real *f, real *g, real *h__, real *ssmin, real * + ssmax) +{ + /* System generated locals */ + real r__1, r__2; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real c__, fa, ga, ha, as, at, au, fhmn, fhmx; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + September 30, 1994 + + + Purpose + ======= + + SLAS2 computes the singular values of the 2-by-2 matrix + [ F G ] + [ 0 H ]. + On return, SSMIN is the smaller singular value and SSMAX is the + larger singular value. + + Arguments + ========= + + F (input) REAL + The (1,1) element of the 2-by-2 matrix. + + G (input) REAL + The (1,2) element of the 2-by-2 matrix. + + H (input) REAL + The (2,2) element of the 2-by-2 matrix. + + SSMIN (output) REAL + The smaller singular value. + + SSMAX (output) REAL + The larger singular value. + + Further Details + =============== + + Barring over/underflow, all output quantities are correct to within + a few units in the last place (ulps), even in the absence of a guard + digit in addition/subtraction. + + In IEEE arithmetic, the code works correctly if one matrix element is + infinite. + + Overflow will not occur unless the largest singular value itself + overflows, or is within a few ulps of overflow. (On machines with + partial overflow, like the Cray, overflow may occur if the largest + singular value is within a factor of 2 of overflow.) + + Underflow is harmless if underflow is gradual. Otherwise, results + may correspond to a matrix modified by perturbations of size near + the underflow threshold. + + ==================================================================== +*/ + + + fa = dabs(*f); + ga = dabs(*g); + ha = dabs(*h__); + fhmn = dmin(fa,ha); + fhmx = dmax(fa,ha); + if (fhmn == 0.f) { + *ssmin = 0.f; + if (fhmx == 0.f) { + *ssmax = ga; + } else { +/* Computing 2nd power */ + r__1 = dmin(fhmx,ga) / dmax(fhmx,ga); + *ssmax = dmax(fhmx,ga) * sqrt(r__1 * r__1 + 1.f); + } + } else { + if (ga < fhmx) { + as = fhmn / fhmx + 1.f; + at = (fhmx - fhmn) / fhmx; +/* Computing 2nd power */ + r__1 = ga / fhmx; + au = r__1 * r__1; + c__ = 2.f / (sqrt(as * as + au) + sqrt(at * at + au)); + *ssmin = fhmn * c__; + *ssmax = fhmx / c__; + } else { + au = fhmx / ga; + if (au == 0.f) { + +/* + Avoid possible harmful underflow if exponent range + asymmetric (true SSMIN may not underflow even if + AU underflows) +*/ + + *ssmin = fhmn * fhmx / ga; + *ssmax = ga; + } else { + as = fhmn / fhmx + 1.f; + at = (fhmx - fhmn) / fhmx; +/* Computing 2nd power */ + r__1 = as * au; +/* Computing 2nd power */ + r__2 = at * au; + c__ = 1.f / (sqrt(r__1 * r__1 + 1.f) + sqrt(r__2 * r__2 + 1.f) + ); + *ssmin = fhmn * c__ * au; + *ssmin += *ssmin; + *ssmax = ga / (c__ + c__); + } + } + } + return 0; + +/* End of SLAS2 */ + +} /* slas2_ */ + +/* Subroutine */ int slascl_(char *type__, integer *kl, integer *ku, real * + cfrom, real *cto, integer *m, integer *n, real *a, integer *lda, + integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3, i__4, i__5; + + /* Local variables */ + static integer i__, j, k1, k2, k3, k4; + static real mul, cto1; + static logical done; + static real ctoc; + extern logical lsame_(char *, char *); + static integer itype; + static real cfrom1; + extern doublereal slamch_(char *); + static real cfromc; + extern /* Subroutine */ int xerbla_(char *, integer *); + static real bignum, smlnum; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SLASCL multiplies the M by N real matrix A by the real scalar + CTO/CFROM. This is done without over/underflow as long as the final + result CTO*A(I,J)/CFROM does not over/underflow. TYPE specifies that + A may be full, upper triangular, lower triangular, upper Hessenberg, + or banded. + + Arguments + ========= + + TYPE (input) CHARACTER*1 + TYPE indices the storage type of the input matrix. + = 'G': A is a full matrix. + = 'L': A is a lower triangular matrix. + = 'U': A is an upper triangular matrix. + = 'H': A is an upper Hessenberg matrix. + = 'B': A is a symmetric band matrix with lower bandwidth KL + and upper bandwidth KU and with the only the lower + half stored. + = 'Q': A is a symmetric band matrix with lower bandwidth KL + and upper bandwidth KU and with the only the upper + half stored. + = 'Z': A is a band matrix with lower bandwidth KL and upper + bandwidth KU. + + KL (input) INTEGER + The lower bandwidth of A. Referenced only if TYPE = 'B', + 'Q' or 'Z'. + + KU (input) INTEGER + The upper bandwidth of A. Referenced only if TYPE = 'B', + 'Q' or 'Z'. + + CFROM (input) REAL + CTO (input) REAL + The matrix A is multiplied by CTO/CFROM. A(I,J) is computed + without over/underflow if the final result CTO*A(I,J)/CFROM + can be represented without over/underflow. CFROM must be + nonzero. + + M (input) INTEGER + The number of rows of the matrix A. M >= 0. + + N (input) INTEGER + The number of columns of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,M) + The matrix to be multiplied by CTO/CFROM. See TYPE for the + storage type. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + INFO (output) INTEGER + 0 - successful exit + <0 - if INFO = -i, the i-th argument had an illegal value. + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + + /* Function Body */ + *info = 0; + + if (lsame_(type__, "G")) { + itype = 0; + } else if (lsame_(type__, "L")) { + itype = 1; + } else if (lsame_(type__, "U")) { + itype = 2; + } else if (lsame_(type__, "H")) { + itype = 3; + } else if (lsame_(type__, "B")) { + itype = 4; + } else if (lsame_(type__, "Q")) { + itype = 5; + } else if (lsame_(type__, "Z")) { + itype = 6; + } else { + itype = -1; + } + + if (itype == -1) { + *info = -1; + } else if (*cfrom == 0.f) { + *info = -4; + } else if (*m < 0) { + *info = -6; + } else if (*n < 0 || itype == 4 && *n != *m || itype == 5 && *n != *m) { + *info = -7; + } else if (itype <= 3 && *lda < max(1,*m)) { + *info = -9; + } else if (itype >= 4) { +/* Computing MAX */ + i__1 = *m - 1; + if (*kl < 0 || *kl > max(i__1,0)) { + *info = -2; + } else /* if(complicated condition) */ { +/* Computing MAX */ + i__1 = *n - 1; + if (*ku < 0 || *ku > max(i__1,0) || (itype == 4 || itype == 5) && + *kl != *ku) { + *info = -3; + } else if (itype == 4 && *lda < *kl + 1 || itype == 5 && *lda < * + ku + 1 || itype == 6 && *lda < (*kl << 1) + *ku + 1) { + *info = -9; + } + } + } + + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLASCL", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0 || *m == 0) { + return 0; + } + +/* Get machine parameters */ + + smlnum = slamch_("S"); + bignum = 1.f / smlnum; + + cfromc = *cfrom; + ctoc = *cto; + +L10: + cfrom1 = cfromc * smlnum; + cto1 = ctoc / bignum; + if (dabs(cfrom1) > dabs(ctoc) && ctoc != 0.f) { + mul = smlnum; + done = FALSE_; + cfromc = cfrom1; + } else if (dabs(cto1) > dabs(cfromc)) { + mul = bignum; + done = FALSE_; + ctoc = cto1; + } else { + mul = ctoc / cfromc; + done = TRUE_; + } + + if (itype == 0) { + +/* Full matrix */ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] *= mul; +/* L20: */ + } +/* L30: */ + } + + } else if (itype == 1) { + +/* Lower triangular matrix */ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = j; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] *= mul; +/* L40: */ + } +/* L50: */ + } + + } else if (itype == 2) { + +/* Upper triangular matrix */ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = min(j,*m); + for (i__ = 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] *= mul; +/* L60: */ + } +/* L70: */ + } + + } else if (itype == 3) { + +/* Upper Hessenberg matrix */ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { +/* Computing MIN */ + i__3 = j + 1; + i__2 = min(i__3,*m); + for (i__ = 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] *= mul; +/* L80: */ + } +/* L90: */ + } + + } else if (itype == 4) { + +/* Lower half of a symmetric band matrix */ + + k3 = *kl + 1; + k4 = *n + 1; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { +/* Computing MIN */ + i__3 = k3, i__4 = k4 - j; + i__2 = min(i__3,i__4); + for (i__ = 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] *= mul; +/* L100: */ + } +/* L110: */ + } + + } else if (itype == 5) { + +/* Upper half of a symmetric band matrix */ + + k1 = *ku + 2; + k3 = *ku + 1; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { +/* Computing MAX */ + i__2 = k1 - j; + i__3 = k3; + for (i__ = max(i__2,1); i__ <= i__3; ++i__) { + a[i__ + j * a_dim1] *= mul; +/* L120: */ + } +/* L130: */ + } + + } else if (itype == 6) { + +/* Band matrix */ + + k1 = *kl + *ku + 2; + k2 = *kl + 1; + k3 = (*kl << 1) + *ku + 1; + k4 = *kl + *ku + 1 + *m; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { +/* Computing MAX */ + i__3 = k1 - j; +/* Computing MIN */ + i__4 = k3, i__5 = k4 - j; + i__2 = min(i__4,i__5); + for (i__ = max(i__3,k2); i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] *= mul; +/* L140: */ + } +/* L150: */ + } + + } + + if (! done) { + goto L10; + } + + return 0; + +/* End of SLASCL */ + +} /* slascl_ */ + +/* Subroutine */ int slasd0_(integer *n, integer *sqre, real *d__, real *e, + real *u, integer *ldu, real *vt, integer *ldvt, integer *smlsiz, + integer *iwork, real *work, integer *info) +{ + /* System generated locals */ + integer u_dim1, u_offset, vt_dim1, vt_offset, i__1, i__2; + + /* Builtin functions */ + integer pow_ii(integer *, integer *); + + /* Local variables */ + static integer i__, j, m, i1, ic, lf, nd, ll, nl, nr, im1, ncc, nlf, nrf, + iwk, lvl, ndb1, nlp1, nrp1; + static real beta; + static integer idxq, nlvl; + static real alpha; + static integer inode, ndiml, idxqc, ndimr, itemp, sqrei; + extern /* Subroutine */ int slasd1_(integer *, integer *, integer *, real + *, real *, real *, real *, integer *, real *, integer *, integer * + , integer *, real *, integer *), xerbla_(char *, integer *), slasdq_(char *, integer *, integer *, integer *, integer + *, integer *, real *, real *, real *, integer *, real *, integer * + , real *, integer *, real *, integer *), slasdt_(integer * + , integer *, integer *, integer *, integer *, integer *, integer * + ); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + Using a divide and conquer approach, SLASD0 computes the singular + value decomposition (SVD) of a real upper bidiagonal N-by-M + matrix B with diagonal D and offdiagonal E, where M = N + SQRE. + The algorithm computes orthogonal matrices U and VT such that + B = U * S * VT. The singular values S are overwritten on D. + + A related subroutine, SLASDA, computes only the singular values, + and optionally, the singular vectors in compact form. + + Arguments + ========= + + N (input) INTEGER + On entry, the row dimension of the upper bidiagonal matrix. + This is also the dimension of the main diagonal array D. + + SQRE (input) INTEGER + Specifies the column dimension of the bidiagonal matrix. + = 0: The bidiagonal matrix has column dimension M = N; + = 1: The bidiagonal matrix has column dimension M = N+1; + + D (input/output) REAL array, dimension (N) + On entry D contains the main diagonal of the bidiagonal + matrix. + On exit D, if INFO = 0, contains its singular values. + + E (input) REAL array, dimension (M-1) + Contains the subdiagonal entries of the bidiagonal matrix. + On exit, E has been destroyed. + + U (output) REAL array, dimension at least (LDQ, N) + On exit, U contains the left singular vectors. + + LDU (input) INTEGER + On entry, leading dimension of U. + + VT (output) REAL array, dimension at least (LDVT, M) + On exit, VT' contains the right singular vectors. + + LDVT (input) INTEGER + On entry, leading dimension of VT. + + SMLSIZ (input) INTEGER + On entry, maximum size of the subproblems at the + bottom of the computation tree. + + IWORK INTEGER work array. + Dimension must be at least (8 * N) + + WORK REAL work array. + Dimension must be at least (3 * M**2 + 2 * M) + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: if INFO = 1, an singular value did not converge + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --e; + u_dim1 = *ldu; + u_offset = 1 + u_dim1; + u -= u_offset; + vt_dim1 = *ldvt; + vt_offset = 1 + vt_dim1; + vt -= vt_offset; + --iwork; + --work; + + /* Function Body */ + *info = 0; + + if (*n < 0) { + *info = -1; + } else if (*sqre < 0 || *sqre > 1) { + *info = -2; + } + + m = *n + *sqre; + + if (*ldu < *n) { + *info = -6; + } else if (*ldvt < m) { + *info = -8; + } else if (*smlsiz < 3) { + *info = -9; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLASD0", &i__1); + return 0; + } + +/* If the input matrix is too small, call SLASDQ to find the SVD. */ + + if (*n <= *smlsiz) { + slasdq_("U", sqre, n, &m, n, &c__0, &d__[1], &e[1], &vt[vt_offset], + ldvt, &u[u_offset], ldu, &u[u_offset], ldu, &work[1], info); + return 0; + } + +/* Set up the computation tree. */ + + inode = 1; + ndiml = inode + *n; + ndimr = ndiml + *n; + idxq = ndimr + *n; + iwk = idxq + *n; + slasdt_(n, &nlvl, &nd, &iwork[inode], &iwork[ndiml], &iwork[ndimr], + smlsiz); + +/* + For the nodes on bottom level of the tree, solve + their subproblems by SLASDQ. +*/ + + ndb1 = (nd + 1) / 2; + ncc = 0; + i__1 = nd; + for (i__ = ndb1; i__ <= i__1; ++i__) { + +/* + IC : center row of each node + NL : number of rows of left subproblem + NR : number of rows of right subproblem + NLF: starting row of the left subproblem + NRF: starting row of the right subproblem +*/ + + i1 = i__ - 1; + ic = iwork[inode + i1]; + nl = iwork[ndiml + i1]; + nlp1 = nl + 1; + nr = iwork[ndimr + i1]; + nrp1 = nr + 1; + nlf = ic - nl; + nrf = ic + 1; + sqrei = 1; + slasdq_("U", &sqrei, &nl, &nlp1, &nl, &ncc, &d__[nlf], &e[nlf], &vt[ + nlf + nlf * vt_dim1], ldvt, &u[nlf + nlf * u_dim1], ldu, &u[ + nlf + nlf * u_dim1], ldu, &work[1], info); + if (*info != 0) { + return 0; + } + itemp = idxq + nlf - 2; + i__2 = nl; + for (j = 1; j <= i__2; ++j) { + iwork[itemp + j] = j; +/* L10: */ + } + if (i__ == nd) { + sqrei = *sqre; + } else { + sqrei = 1; + } + nrp1 = nr + sqrei; + slasdq_("U", &sqrei, &nr, &nrp1, &nr, &ncc, &d__[nrf], &e[nrf], &vt[ + nrf + nrf * vt_dim1], ldvt, &u[nrf + nrf * u_dim1], ldu, &u[ + nrf + nrf * u_dim1], ldu, &work[1], info); + if (*info != 0) { + return 0; + } + itemp = idxq + ic; + i__2 = nr; + for (j = 1; j <= i__2; ++j) { + iwork[itemp + j - 1] = j; +/* L20: */ + } +/* L30: */ + } + +/* Now conquer each subproblem bottom-up. */ + + for (lvl = nlvl; lvl >= 1; --lvl) { + +/* + Find the first node LF and last node LL on the + current level LVL. +*/ + + if (lvl == 1) { + lf = 1; + ll = 1; + } else { + i__1 = lvl - 1; + lf = pow_ii(&c__2, &i__1); + ll = (lf << 1) - 1; + } + i__1 = ll; + for (i__ = lf; i__ <= i__1; ++i__) { + im1 = i__ - 1; + ic = iwork[inode + im1]; + nl = iwork[ndiml + im1]; + nr = iwork[ndimr + im1]; + nlf = ic - nl; + if (*sqre == 0 && i__ == ll) { + sqrei = *sqre; + } else { + sqrei = 1; + } + idxqc = idxq + nlf - 1; + alpha = d__[ic]; + beta = e[ic]; + slasd1_(&nl, &nr, &sqrei, &d__[nlf], &alpha, &beta, &u[nlf + nlf * + u_dim1], ldu, &vt[nlf + nlf * vt_dim1], ldvt, &iwork[ + idxqc], &iwork[iwk], &work[1], info); + if (*info != 0) { + return 0; + } +/* L40: */ + } +/* L50: */ + } + + return 0; + +/* End of SLASD0 */ + +} /* slasd0_ */ + +/* Subroutine */ int slasd1_(integer *nl, integer *nr, integer *sqre, real * + d__, real *alpha, real *beta, real *u, integer *ldu, real *vt, + integer *ldvt, integer *idxq, integer *iwork, real *work, integer * + info) +{ + /* System generated locals */ + integer u_dim1, u_offset, vt_dim1, vt_offset, i__1; + real r__1, r__2; + + /* Local variables */ + static integer i__, k, m, n, n1, n2, iq, iz, iu2, ldq, idx, ldu2, ivt2, + idxc, idxp, ldvt2; + extern /* Subroutine */ int slasd2_(integer *, integer *, integer *, + integer *, real *, real *, real *, real *, real *, integer *, + real *, integer *, real *, real *, integer *, real *, integer *, + integer *, integer *, integer *, integer *, integer *, integer *), + slasd3_(integer *, integer *, integer *, integer *, real *, real + *, integer *, real *, real *, integer *, real *, integer *, real * + , integer *, real *, integer *, integer *, integer *, real *, + integer *); + static integer isigma; + extern /* Subroutine */ int xerbla_(char *, integer *), slascl_( + char *, integer *, integer *, real *, real *, integer *, integer * + , real *, integer *, integer *), slamrg_(integer *, + integer *, real *, integer *, integer *, integer *); + static real orgnrm; + static integer coltyp; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SLASD1 computes the SVD of an upper bidiagonal N-by-M matrix B, + where N = NL + NR + 1 and M = N + SQRE. SLASD1 is called from SLASD0. + + A related subroutine SLASD7 handles the case in which the singular + values (and the singular vectors in factored form) are desired. + + SLASD1 computes the SVD as follows: + + ( D1(in) 0 0 0 ) + B = U(in) * ( Z1' a Z2' b ) * VT(in) + ( 0 0 D2(in) 0 ) + + = U(out) * ( D(out) 0) * VT(out) + + where Z' = (Z1' a Z2' b) = u' VT', and u is a vector of dimension M + with ALPHA and BETA in the NL+1 and NL+2 th entries and zeros + elsewhere; and the entry b is empty if SQRE = 0. + + The left singular vectors of the original matrix are stored in U, and + the transpose of the right singular vectors are stored in VT, and the + singular values are in D. The algorithm consists of three stages: + + The first stage consists of deflating the size of the problem + when there are multiple singular values or when there are zeros in + the Z vector. For each such occurence the dimension of the + secular equation problem is reduced by one. This stage is + performed by the routine SLASD2. + + The second stage consists of calculating the updated + singular values. This is done by finding the square roots of the + roots of the secular equation via the routine SLASD4 (as called + by SLASD3). This routine also calculates the singular vectors of + the current problem. + + The final stage consists of computing the updated singular vectors + directly using the updated singular values. The singular vectors + for the current problem are multiplied with the singular vectors + from the overall problem. + + Arguments + ========= + + NL (input) INTEGER + The row dimension of the upper block. NL >= 1. + + NR (input) INTEGER + The row dimension of the lower block. NR >= 1. + + SQRE (input) INTEGER + = 0: the lower block is an NR-by-NR square matrix. + = 1: the lower block is an NR-by-(NR+1) rectangular matrix. + + The bidiagonal matrix has row dimension N = NL + NR + 1, + and column dimension M = N + SQRE. + + D (input/output) REAL array, + dimension (N = NL+NR+1). + On entry D(1:NL,1:NL) contains the singular values of the + upper block; and D(NL+2:N) contains the singular values of + the lower block. On exit D(1:N) contains the singular values + of the modified matrix. + + ALPHA (input) REAL + Contains the diagonal element associated with the added row. + + BETA (input) REAL + Contains the off-diagonal element associated with the added + row. + + U (input/output) REAL array, dimension(LDU,N) + On entry U(1:NL, 1:NL) contains the left singular vectors of + the upper block; U(NL+2:N, NL+2:N) contains the left singular + vectors of the lower block. On exit U contains the left + singular vectors of the bidiagonal matrix. + + LDU (input) INTEGER + The leading dimension of the array U. LDU >= max( 1, N ). + + VT (input/output) REAL array, dimension(LDVT,M) + where M = N + SQRE. + On entry VT(1:NL+1, 1:NL+1)' contains the right singular + vectors of the upper block; VT(NL+2:M, NL+2:M)' contains + the right singular vectors of the lower block. On exit + VT' contains the right singular vectors of the + bidiagonal matrix. + + LDVT (input) INTEGER + The leading dimension of the array VT. LDVT >= max( 1, M ). + + IDXQ (output) INTEGER array, dimension(N) + This contains the permutation which will reintegrate the + subproblem just solved back into sorted order, i.e. + D( IDXQ( I = 1, N ) ) will be in ascending order. + + IWORK (workspace) INTEGER array, dimension( 4 * N ) + + WORK (workspace) REAL array, dimension( 3*M**2 + 2*M ) + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: if INFO = 1, an singular value did not converge + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + u_dim1 = *ldu; + u_offset = 1 + u_dim1; + u -= u_offset; + vt_dim1 = *ldvt; + vt_offset = 1 + vt_dim1; + vt -= vt_offset; + --idxq; + --iwork; + --work; + + /* Function Body */ + *info = 0; + + if (*nl < 1) { + *info = -1; + } else if (*nr < 1) { + *info = -2; + } else if (*sqre < 0 || *sqre > 1) { + *info = -3; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLASD1", &i__1); + return 0; + } + + n = *nl + *nr + 1; + m = n + *sqre; + +/* + The following values are for bookkeeping purposes only. They are + integer pointers which indicate the portion of the workspace + used by a particular array in SLASD2 and SLASD3. +*/ + + ldu2 = n; + ldvt2 = m; + + iz = 1; + isigma = iz + m; + iu2 = isigma + n; + ivt2 = iu2 + ldu2 * n; + iq = ivt2 + ldvt2 * m; + + idx = 1; + idxc = idx + n; + coltyp = idxc + n; + idxp = coltyp + n; + +/* + Scale. + + Computing MAX +*/ + r__1 = dabs(*alpha), r__2 = dabs(*beta); + orgnrm = dmax(r__1,r__2); + d__[*nl + 1] = 0.f; + i__1 = n; + for (i__ = 1; i__ <= i__1; ++i__) { + if ((r__1 = d__[i__], dabs(r__1)) > orgnrm) { + orgnrm = (r__1 = d__[i__], dabs(r__1)); + } +/* L10: */ + } + slascl_("G", &c__0, &c__0, &orgnrm, &c_b15, &n, &c__1, &d__[1], &n, info); + *alpha /= orgnrm; + *beta /= orgnrm; + +/* Deflate singular values. */ + + slasd2_(nl, nr, sqre, &k, &d__[1], &work[iz], alpha, beta, &u[u_offset], + ldu, &vt[vt_offset], ldvt, &work[isigma], &work[iu2], &ldu2, & + work[ivt2], &ldvt2, &iwork[idxp], &iwork[idx], &iwork[idxc], & + idxq[1], &iwork[coltyp], info); + +/* Solve Secular Equation and update singular vectors. */ + + ldq = k; + slasd3_(nl, nr, sqre, &k, &d__[1], &work[iq], &ldq, &work[isigma], &u[ + u_offset], ldu, &work[iu2], &ldu2, &vt[vt_offset], ldvt, &work[ + ivt2], &ldvt2, &iwork[idxc], &iwork[coltyp], &work[iz], info); + if (*info != 0) { + return 0; + } + +/* Unscale. */ + + slascl_("G", &c__0, &c__0, &c_b15, &orgnrm, &n, &c__1, &d__[1], &n, info); + +/* Prepare the IDXQ sorting permutation. */ + + n1 = k; + n2 = n - k; + slamrg_(&n1, &n2, &d__[1], &c__1, &c_n1, &idxq[1]); + + return 0; + +/* End of SLASD1 */ + +} /* slasd1_ */ + +/* Subroutine */ int slasd2_(integer *nl, integer *nr, integer *sqre, integer + *k, real *d__, real *z__, real *alpha, real *beta, real *u, integer * + ldu, real *vt, integer *ldvt, real *dsigma, real *u2, integer *ldu2, + real *vt2, integer *ldvt2, integer *idxp, integer *idx, integer *idxc, + integer *idxq, integer *coltyp, integer *info) +{ + /* System generated locals */ + integer u_dim1, u_offset, u2_dim1, u2_offset, vt_dim1, vt_offset, + vt2_dim1, vt2_offset, i__1; + real r__1, r__2; + + /* Local variables */ + static real c__; + static integer i__, j, m, n; + static real s; + static integer k2; + static real z1; + static integer ct, jp; + static real eps, tau, tol; + static integer psm[4], nlp1, nlp2, idxi, idxj, ctot[4]; + extern /* Subroutine */ int srot_(integer *, real *, integer *, real *, + integer *, real *, real *); + static integer idxjp, jprev; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *); + extern doublereal slapy2_(real *, real *), slamch_(char *); + extern /* Subroutine */ int xerbla_(char *, integer *), slamrg_( + integer *, integer *, real *, integer *, integer *, integer *); + static real hlftol; + extern /* Subroutine */ int slacpy_(char *, integer *, integer *, real *, + integer *, real *, integer *), slaset_(char *, integer *, + integer *, real *, real *, real *, integer *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + October 31, 1999 + + + Purpose + ======= + + SLASD2 merges the two sets of singular values together into a single + sorted set. Then it tries to deflate the size of the problem. + There are two ways in which deflation can occur: when two or more + singular values are close together or if there is a tiny entry in the + Z vector. For each such occurrence the order of the related secular + equation problem is reduced by one. + + SLASD2 is called from SLASD1. + + Arguments + ========= + + NL (input) INTEGER + The row dimension of the upper block. NL >= 1. + + NR (input) INTEGER + The row dimension of the lower block. NR >= 1. + + SQRE (input) INTEGER + = 0: the lower block is an NR-by-NR square matrix. + = 1: the lower block is an NR-by-(NR+1) rectangular matrix. + + The bidiagonal matrix has N = NL + NR + 1 rows and + M = N + SQRE >= N columns. + + K (output) INTEGER + Contains the dimension of the non-deflated matrix, + This is the order of the related secular equation. 1 <= K <=N. + + D (input/output) REAL array, dimension(N) + On entry D contains the singular values of the two submatrices + to be combined. On exit D contains the trailing (N-K) updated + singular values (those which were deflated) sorted into + increasing order. + + ALPHA (input) REAL + Contains the diagonal element associated with the added row. + + BETA (input) REAL + Contains the off-diagonal element associated with the added + row. + + U (input/output) REAL array, dimension(LDU,N) + On entry U contains the left singular vectors of two + submatrices in the two square blocks with corners at (1,1), + (NL, NL), and (NL+2, NL+2), (N,N). + On exit U contains the trailing (N-K) updated left singular + vectors (those which were deflated) in its last N-K columns. + + LDU (input) INTEGER + The leading dimension of the array U. LDU >= N. + + Z (output) REAL array, dimension(N) + On exit Z contains the updating row vector in the secular + equation. + + DSIGMA (output) REAL array, dimension (N) + Contains a copy of the diagonal elements (K-1 singular values + and one zero) in the secular equation. + + U2 (output) REAL array, dimension(LDU2,N) + Contains a copy of the first K-1 left singular vectors which + will be used by SLASD3 in a matrix multiply (SGEMM) to solve + for the new left singular vectors. U2 is arranged into four + blocks. The first block contains a column with 1 at NL+1 and + zero everywhere else; the second block contains non-zero + entries only at and above NL; the third contains non-zero + entries only below NL+1; and the fourth is dense. + + LDU2 (input) INTEGER + The leading dimension of the array U2. LDU2 >= N. + + VT (input/output) REAL array, dimension(LDVT,M) + On entry VT' contains the right singular vectors of two + submatrices in the two square blocks with corners at (1,1), + (NL+1, NL+1), and (NL+2, NL+2), (M,M). + On exit VT' contains the trailing (N-K) updated right singular + vectors (those which were deflated) in its last N-K columns. + In case SQRE =1, the last row of VT spans the right null + space. + + LDVT (input) INTEGER + The leading dimension of the array VT. LDVT >= M. + + VT2 (output) REAL array, dimension(LDVT2,N) + VT2' contains a copy of the first K right singular vectors + which will be used by SLASD3 in a matrix multiply (SGEMM) to + solve for the new right singular vectors. VT2 is arranged into + three blocks. The first block contains a row that corresponds + to the special 0 diagonal element in SIGMA; the second block + contains non-zeros only at and before NL +1; the third block + contains non-zeros only at and after NL +2. + + LDVT2 (input) INTEGER + The leading dimension of the array VT2. LDVT2 >= M. + + IDXP (workspace) INTEGER array, dimension(N) + This will contain the permutation used to place deflated + values of D at the end of the array. On output IDXP(2:K) + points to the nondeflated D-values and IDXP(K+1:N) + points to the deflated singular values. + + IDX (workspace) INTEGER array, dimension(N) + This will contain the permutation used to sort the contents of + D into ascending order. + + IDXC (output) INTEGER array, dimension(N) + This will contain the permutation used to arrange the columns + of the deflated U matrix into three groups: the first group + contains non-zero entries only at and above NL, the second + contains non-zero entries only below NL+2, and the third is + dense. + + COLTYP (workspace/output) INTEGER array, dimension(N) + As workspace, this will contain a label which will indicate + which of the following types a column in the U2 matrix or a + row in the VT2 matrix is: + 1 : non-zero in the upper half only + 2 : non-zero in the lower half only + 3 : dense + 4 : deflated + + On exit, it is an array of dimension 4, with COLTYP(I) being + the dimension of the I-th type columns. + + IDXQ (input) INTEGER array, dimension(N) + This contains the permutation which separately sorts the two + sub-problems in D into ascending order. Note that entries in + the first hlaf of this permutation must first be moved one + position backward; and entries in the second half + must first have NL+1 added to their values. + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --z__; + u_dim1 = *ldu; + u_offset = 1 + u_dim1; + u -= u_offset; + vt_dim1 = *ldvt; + vt_offset = 1 + vt_dim1; + vt -= vt_offset; + --dsigma; + u2_dim1 = *ldu2; + u2_offset = 1 + u2_dim1; + u2 -= u2_offset; + vt2_dim1 = *ldvt2; + vt2_offset = 1 + vt2_dim1; + vt2 -= vt2_offset; + --idxp; + --idx; + --idxc; + --idxq; + --coltyp; + + /* Function Body */ + *info = 0; + + if (*nl < 1) { + *info = -1; + } else if (*nr < 1) { + *info = -2; + } else if (*sqre != 1 && *sqre != 0) { + *info = -3; + } + + n = *nl + *nr + 1; + m = n + *sqre; + + if (*ldu < n) { + *info = -10; + } else if (*ldvt < m) { + *info = -12; + } else if (*ldu2 < n) { + *info = -15; + } else if (*ldvt2 < m) { + *info = -17; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLASD2", &i__1); + return 0; + } + + nlp1 = *nl + 1; + nlp2 = *nl + 2; + +/* + Generate the first part of the vector Z; and move the singular + values in the first part of D one position backward. +*/ + + z1 = *alpha * vt[nlp1 + nlp1 * vt_dim1]; + z__[1] = z1; + for (i__ = *nl; i__ >= 1; --i__) { + z__[i__ + 1] = *alpha * vt[i__ + nlp1 * vt_dim1]; + d__[i__ + 1] = d__[i__]; + idxq[i__ + 1] = idxq[i__] + 1; +/* L10: */ + } + +/* Generate the second part of the vector Z. */ + + i__1 = m; + for (i__ = nlp2; i__ <= i__1; ++i__) { + z__[i__] = *beta * vt[i__ + nlp2 * vt_dim1]; +/* L20: */ + } + +/* Initialize some reference arrays. */ + + i__1 = nlp1; + for (i__ = 2; i__ <= i__1; ++i__) { + coltyp[i__] = 1; +/* L30: */ + } + i__1 = n; + for (i__ = nlp2; i__ <= i__1; ++i__) { + coltyp[i__] = 2; +/* L40: */ + } + +/* Sort the singular values into increasing order */ + + i__1 = n; + for (i__ = nlp2; i__ <= i__1; ++i__) { + idxq[i__] += nlp1; +/* L50: */ + } + +/* + DSIGMA, IDXC, IDXC, and the first column of U2 + are used as storage space. +*/ + + i__1 = n; + for (i__ = 2; i__ <= i__1; ++i__) { + dsigma[i__] = d__[idxq[i__]]; + u2[i__ + u2_dim1] = z__[idxq[i__]]; + idxc[i__] = coltyp[idxq[i__]]; +/* L60: */ + } + + slamrg_(nl, nr, &dsigma[2], &c__1, &c__1, &idx[2]); + + i__1 = n; + for (i__ = 2; i__ <= i__1; ++i__) { + idxi = idx[i__] + 1; + d__[i__] = dsigma[idxi]; + z__[i__] = u2[idxi + u2_dim1]; + coltyp[i__] = idxc[idxi]; +/* L70: */ + } + +/* Calculate the allowable deflation tolerance */ + + eps = slamch_("Epsilon"); +/* Computing MAX */ + r__1 = dabs(*alpha), r__2 = dabs(*beta); + tol = dmax(r__1,r__2); +/* Computing MAX */ + r__2 = (r__1 = d__[n], dabs(r__1)); + tol = eps * 8.f * dmax(r__2,tol); + +/* + There are 2 kinds of deflation -- first a value in the z-vector + is small, second two (or more) singular values are very close + together (their difference is small). + + If the value in the z-vector is small, we simply permute the + array so that the corresponding singular value is moved to the + end. + + If two values in the D-vector are close, we perform a two-sided + rotation designed to make one of the corresponding z-vector + entries zero, and then permute the array so that the deflated + singular value is moved to the end. + + If there are multiple singular values then the problem deflates. + Here the number of equal singular values are found. As each equal + singular value is found, an elementary reflector is computed to + rotate the corresponding singular subspace so that the + corresponding components of Z are zero in this new basis. +*/ + + *k = 1; + k2 = n + 1; + i__1 = n; + for (j = 2; j <= i__1; ++j) { + if ((r__1 = z__[j], dabs(r__1)) <= tol) { + +/* Deflate due to small z component. */ + + --k2; + idxp[k2] = j; + coltyp[j] = 4; + if (j == n) { + goto L120; + } + } else { + jprev = j; + goto L90; + } +/* L80: */ + } +L90: + j = jprev; +L100: + ++j; + if (j > n) { + goto L110; + } + if ((r__1 = z__[j], dabs(r__1)) <= tol) { + +/* Deflate due to small z component. */ + + --k2; + idxp[k2] = j; + coltyp[j] = 4; + } else { + +/* Check if singular values are close enough to allow deflation. */ + + if ((r__1 = d__[j] - d__[jprev], dabs(r__1)) <= tol) { + +/* Deflation is possible. */ + + s = z__[jprev]; + c__ = z__[j]; + +/* + Find sqrt(a**2+b**2) without overflow or + destructive underflow. +*/ + + tau = slapy2_(&c__, &s); + c__ /= tau; + s = -s / tau; + z__[j] = tau; + z__[jprev] = 0.f; + +/* + Apply back the Givens rotation to the left and right + singular vector matrices. +*/ + + idxjp = idxq[idx[jprev] + 1]; + idxj = idxq[idx[j] + 1]; + if (idxjp <= nlp1) { + --idxjp; + } + if (idxj <= nlp1) { + --idxj; + } + srot_(&n, &u[idxjp * u_dim1 + 1], &c__1, &u[idxj * u_dim1 + 1], & + c__1, &c__, &s); + srot_(&m, &vt[idxjp + vt_dim1], ldvt, &vt[idxj + vt_dim1], ldvt, & + c__, &s); + if (coltyp[j] != coltyp[jprev]) { + coltyp[j] = 3; + } + coltyp[jprev] = 4; + --k2; + idxp[k2] = jprev; + jprev = j; + } else { + ++(*k); + u2[*k + u2_dim1] = z__[jprev]; + dsigma[*k] = d__[jprev]; + idxp[*k] = jprev; + jprev = j; + } + } + goto L100; +L110: + +/* Record the last singular value. */ + + ++(*k); + u2[*k + u2_dim1] = z__[jprev]; + dsigma[*k] = d__[jprev]; + idxp[*k] = jprev; + +L120: + +/* + Count up the total number of the various types of columns, then + form a permutation which positions the four column types into + four groups of uniform structure (although one or more of these + groups may be empty). +*/ + + for (j = 1; j <= 4; ++j) { + ctot[j - 1] = 0; +/* L130: */ + } + i__1 = n; + for (j = 2; j <= i__1; ++j) { + ct = coltyp[j]; + ++ctot[ct - 1]; +/* L140: */ + } + +/* PSM(*) = Position in SubMatrix (of types 1 through 4) */ + + psm[0] = 2; + psm[1] = ctot[0] + 2; + psm[2] = psm[1] + ctot[1]; + psm[3] = psm[2] + ctot[2]; + +/* + Fill out the IDXC array so that the permutation which it induces + will place all type-1 columns first, all type-2 columns next, + then all type-3's, and finally all type-4's, starting from the + second column. This applies similarly to the rows of VT. +*/ + + i__1 = n; + for (j = 2; j <= i__1; ++j) { + jp = idxp[j]; + ct = coltyp[jp]; + idxc[psm[ct - 1]] = j; + ++psm[ct - 1]; +/* L150: */ + } + +/* + Sort the singular values and corresponding singular vectors into + DSIGMA, U2, and VT2 respectively. The singular values/vectors + which were not deflated go into the first K slots of DSIGMA, U2, + and VT2 respectively, while those which were deflated go into the + last N - K slots, except that the first column/row will be treated + separately. +*/ + + i__1 = n; + for (j = 2; j <= i__1; ++j) { + jp = idxp[j]; + dsigma[j] = d__[jp]; + idxj = idxq[idx[idxp[idxc[j]]] + 1]; + if (idxj <= nlp1) { + --idxj; + } + scopy_(&n, &u[idxj * u_dim1 + 1], &c__1, &u2[j * u2_dim1 + 1], &c__1); + scopy_(&m, &vt[idxj + vt_dim1], ldvt, &vt2[j + vt2_dim1], ldvt2); +/* L160: */ + } + +/* Determine DSIGMA(1), DSIGMA(2) and Z(1) */ + + dsigma[1] = 0.f; + hlftol = tol / 2.f; + if (dabs(dsigma[2]) <= hlftol) { + dsigma[2] = hlftol; + } + if (m > n) { + z__[1] = slapy2_(&z1, &z__[m]); + if (z__[1] <= tol) { + c__ = 1.f; + s = 0.f; + z__[1] = tol; + } else { + c__ = z1 / z__[1]; + s = z__[m] / z__[1]; + } + } else { + if (dabs(z1) <= tol) { + z__[1] = tol; + } else { + z__[1] = z1; + } + } + +/* Move the rest of the updating row to Z. */ + + i__1 = *k - 1; + scopy_(&i__1, &u2[u2_dim1 + 2], &c__1, &z__[2], &c__1); + +/* + Determine the first column of U2, the first row of VT2 and the + last row of VT. +*/ + + slaset_("A", &n, &c__1, &c_b29, &c_b29, &u2[u2_offset], ldu2); + u2[nlp1 + u2_dim1] = 1.f; + if (m > n) { + i__1 = nlp1; + for (i__ = 1; i__ <= i__1; ++i__) { + vt[m + i__ * vt_dim1] = -s * vt[nlp1 + i__ * vt_dim1]; + vt2[i__ * vt2_dim1 + 1] = c__ * vt[nlp1 + i__ * vt_dim1]; +/* L170: */ + } + i__1 = m; + for (i__ = nlp2; i__ <= i__1; ++i__) { + vt2[i__ * vt2_dim1 + 1] = s * vt[m + i__ * vt_dim1]; + vt[m + i__ * vt_dim1] = c__ * vt[m + i__ * vt_dim1]; +/* L180: */ + } + } else { + scopy_(&m, &vt[nlp1 + vt_dim1], ldvt, &vt2[vt2_dim1 + 1], ldvt2); + } + if (m > n) { + scopy_(&m, &vt[m + vt_dim1], ldvt, &vt2[m + vt2_dim1], ldvt2); + } + +/* + The deflated singular values and their corresponding vectors go + into the back of D, U, and V respectively. +*/ + + if (n > *k) { + i__1 = n - *k; + scopy_(&i__1, &dsigma[*k + 1], &c__1, &d__[*k + 1], &c__1); + i__1 = n - *k; + slacpy_("A", &n, &i__1, &u2[(*k + 1) * u2_dim1 + 1], ldu2, &u[(*k + 1) + * u_dim1 + 1], ldu); + i__1 = n - *k; + slacpy_("A", &i__1, &m, &vt2[*k + 1 + vt2_dim1], ldvt2, &vt[*k + 1 + + vt_dim1], ldvt); + } + +/* Copy CTOT into COLTYP for referencing in SLASD3. */ + + for (j = 1; j <= 4; ++j) { + coltyp[j] = ctot[j - 1]; +/* L190: */ + } + + return 0; + +/* End of SLASD2 */ + +} /* slasd2_ */ + +/* Subroutine */ int slasd3_(integer *nl, integer *nr, integer *sqre, integer + *k, real *d__, real *q, integer *ldq, real *dsigma, real *u, integer * + ldu, real *u2, integer *ldu2, real *vt, integer *ldvt, real *vt2, + integer *ldvt2, integer *idxc, integer *ctot, real *z__, integer * + info) +{ + /* System generated locals */ + integer q_dim1, q_offset, u_dim1, u_offset, u2_dim1, u2_offset, vt_dim1, + vt_offset, vt2_dim1, vt2_offset, i__1, i__2; + real r__1, r__2; + + /* Builtin functions */ + double sqrt(doublereal), r_sign(real *, real *); + + /* Local variables */ + static integer i__, j, m, n, jc; + static real rho; + static integer nlp1, nlp2, nrp1; + static real temp; + extern doublereal snrm2_(integer *, real *, integer *); + static integer ctemp; + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *); + static integer ktemp; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *); + extern doublereal slamc3_(real *, real *); + extern /* Subroutine */ int slasd4_(integer *, integer *, real *, real *, + real *, real *, real *, real *, integer *), xerbla_(char *, + integer *), slascl_(char *, integer *, integer *, real *, + real *, integer *, integer *, real *, integer *, integer *), slacpy_(char *, integer *, integer *, real *, integer *, + real *, integer *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + October 31, 1999 + + + Purpose + ======= + + SLASD3 finds all the square roots of the roots of the secular + equation, as defined by the values in D and Z. It makes the + appropriate calls to SLASD4 and then updates the singular + vectors by matrix multiplication. + + This code makes very mild assumptions about floating point + arithmetic. It will work on machines with a guard digit in + add/subtract, or on those binary machines without guard digits + which subtract like the Cray XMP, Cray YMP, Cray C 90, or Cray 2. + It could conceivably fail on hexadecimal or decimal machines + without guard digits, but we know of none. + + SLASD3 is called from SLASD1. + + Arguments + ========= + + NL (input) INTEGER + The row dimension of the upper block. NL >= 1. + + NR (input) INTEGER + The row dimension of the lower block. NR >= 1. + + SQRE (input) INTEGER + = 0: the lower block is an NR-by-NR square matrix. + = 1: the lower block is an NR-by-(NR+1) rectangular matrix. + + The bidiagonal matrix has N = NL + NR + 1 rows and + M = N + SQRE >= N columns. + + K (input) INTEGER + The size of the secular equation, 1 =< K = < N. + + D (output) REAL array, dimension(K) + On exit the square roots of the roots of the secular equation, + in ascending order. + + Q (workspace) REAL array, + dimension at least (LDQ,K). + + LDQ (input) INTEGER + The leading dimension of the array Q. LDQ >= K. + + DSIGMA (input) REAL array, dimension(K) + The first K elements of this array contain the old roots + of the deflated updating problem. These are the poles + of the secular equation. + + U (input) REAL array, dimension (LDU, N) + The last N - K columns of this matrix contain the deflated + left singular vectors. + + LDU (input) INTEGER + The leading dimension of the array U. LDU >= N. + + U2 (input) REAL array, dimension (LDU2, N) + The first K columns of this matrix contain the non-deflated + left singular vectors for the split problem. + + LDU2 (input) INTEGER + The leading dimension of the array U2. LDU2 >= N. + + VT (input) REAL array, dimension (LDVT, M) + The last M - K columns of VT' contain the deflated + right singular vectors. + + LDVT (input) INTEGER + The leading dimension of the array VT. LDVT >= N. + + VT2 (input) REAL array, dimension (LDVT2, N) + The first K columns of VT2' contain the non-deflated + right singular vectors for the split problem. + + LDVT2 (input) INTEGER + The leading dimension of the array VT2. LDVT2 >= N. + + IDXC (input) INTEGER array, dimension ( N ) + The permutation used to arrange the columns of U (and rows of + VT) into three groups: the first group contains non-zero + entries only at and above (or before) NL +1; the second + contains non-zero entries only at and below (or after) NL+2; + and the third is dense. The first column of U and the row of + VT are treated separately, however. + + The rows of the singular vectors found by SLASD4 + must be likewise permuted before the matrix multiplies can + take place. + + CTOT (input) INTEGER array, dimension ( 4 ) + A count of the total number of the various types of columns + in U (or rows in VT), as described in IDXC. The fourth column + type is any column which has been deflated. + + Z (input) REAL array, dimension (K) + The first K elements of this array contain the components + of the deflation-adjusted updating row vector. + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: if INFO = 1, an singular value did not converge + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + q_dim1 = *ldq; + q_offset = 1 + q_dim1; + q -= q_offset; + --dsigma; + u_dim1 = *ldu; + u_offset = 1 + u_dim1; + u -= u_offset; + u2_dim1 = *ldu2; + u2_offset = 1 + u2_dim1; + u2 -= u2_offset; + vt_dim1 = *ldvt; + vt_offset = 1 + vt_dim1; + vt -= vt_offset; + vt2_dim1 = *ldvt2; + vt2_offset = 1 + vt2_dim1; + vt2 -= vt2_offset; + --idxc; + --ctot; + --z__; + + /* Function Body */ + *info = 0; + + if (*nl < 1) { + *info = -1; + } else if (*nr < 1) { + *info = -2; + } else if (*sqre != 1 && *sqre != 0) { + *info = -3; + } + + n = *nl + *nr + 1; + m = n + *sqre; + nlp1 = *nl + 1; + nlp2 = *nl + 2; + + if (*k < 1 || *k > n) { + *info = -4; + } else if (*ldq < *k) { + *info = -7; + } else if (*ldu < n) { + *info = -10; + } else if (*ldu2 < n) { + *info = -12; + } else if (*ldvt < m) { + *info = -14; + } else if (*ldvt2 < m) { + *info = -16; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLASD3", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*k == 1) { + d__[1] = dabs(z__[1]); + scopy_(&m, &vt2[vt2_dim1 + 1], ldvt2, &vt[vt_dim1 + 1], ldvt); + if (z__[1] > 0.f) { + scopy_(&n, &u2[u2_dim1 + 1], &c__1, &u[u_dim1 + 1], &c__1); + } else { + i__1 = n; + for (i__ = 1; i__ <= i__1; ++i__) { + u[i__ + u_dim1] = -u2[i__ + u2_dim1]; +/* L10: */ + } + } + return 0; + } + +/* + Modify values DSIGMA(i) to make sure all DSIGMA(i)-DSIGMA(j) can + be computed with high relative accuracy (barring over/underflow). + This is a problem on machines without a guard digit in + add/subtract (Cray XMP, Cray YMP, Cray C 90 and Cray 2). + The following code replaces DSIGMA(I) by 2*DSIGMA(I)-DSIGMA(I), + which on any of these machines zeros out the bottommost + bit of DSIGMA(I) if it is 1; this makes the subsequent + subtractions DSIGMA(I)-DSIGMA(J) unproblematic when cancellation + occurs. On binary machines with a guard digit (almost all + machines) it does not change DSIGMA(I) at all. On hexadecimal + and decimal machines with a guard digit, it slightly + changes the bottommost bits of DSIGMA(I). It does not account + for hexadecimal or decimal machines without guard digits + (we know of none). We use a subroutine call to compute + 2*DLAMBDA(I) to prevent optimizing compilers from eliminating + this code. +*/ + + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + dsigma[i__] = slamc3_(&dsigma[i__], &dsigma[i__]) - dsigma[i__]; +/* L20: */ + } + +/* Keep a copy of Z. */ + + scopy_(k, &z__[1], &c__1, &q[q_offset], &c__1); + +/* Normalize Z. */ + + rho = snrm2_(k, &z__[1], &c__1); + slascl_("G", &c__0, &c__0, &rho, &c_b15, k, &c__1, &z__[1], k, info); + rho *= rho; + +/* Find the new singular values. */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + slasd4_(k, &j, &dsigma[1], &z__[1], &u[j * u_dim1 + 1], &rho, &d__[j], + &vt[j * vt_dim1 + 1], info); + +/* If the zero finder fails, the computation is terminated. */ + + if (*info != 0) { + return 0; + } +/* L30: */ + } + +/* Compute updated Z. */ + + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + z__[i__] = u[i__ + *k * u_dim1] * vt[i__ + *k * vt_dim1]; + i__2 = i__ - 1; + for (j = 1; j <= i__2; ++j) { + z__[i__] *= u[i__ + j * u_dim1] * vt[i__ + j * vt_dim1] / (dsigma[ + i__] - dsigma[j]) / (dsigma[i__] + dsigma[j]); +/* L40: */ + } + i__2 = *k - 1; + for (j = i__; j <= i__2; ++j) { + z__[i__] *= u[i__ + j * u_dim1] * vt[i__ + j * vt_dim1] / (dsigma[ + i__] - dsigma[j + 1]) / (dsigma[i__] + dsigma[j + 1]); +/* L50: */ + } + r__2 = sqrt((r__1 = z__[i__], dabs(r__1))); + z__[i__] = r_sign(&r__2, &q[i__ + q_dim1]); +/* L60: */ + } + +/* + Compute left singular vectors of the modified diagonal matrix, + and store related information for the right singular vectors. +*/ + + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + vt[i__ * vt_dim1 + 1] = z__[1] / u[i__ * u_dim1 + 1] / vt[i__ * + vt_dim1 + 1]; + u[i__ * u_dim1 + 1] = -1.f; + i__2 = *k; + for (j = 2; j <= i__2; ++j) { + vt[j + i__ * vt_dim1] = z__[j] / u[j + i__ * u_dim1] / vt[j + i__ + * vt_dim1]; + u[j + i__ * u_dim1] = dsigma[j] * vt[j + i__ * vt_dim1]; +/* L70: */ + } + temp = snrm2_(k, &u[i__ * u_dim1 + 1], &c__1); + q[i__ * q_dim1 + 1] = u[i__ * u_dim1 + 1] / temp; + i__2 = *k; + for (j = 2; j <= i__2; ++j) { + jc = idxc[j]; + q[j + i__ * q_dim1] = u[jc + i__ * u_dim1] / temp; +/* L80: */ + } +/* L90: */ + } + +/* Update the left singular vector matrix. */ + + if (*k == 2) { + sgemm_("N", "N", &n, k, k, &c_b15, &u2[u2_offset], ldu2, &q[q_offset], + ldq, &c_b29, &u[u_offset], ldu); + goto L100; + } + if (ctot[1] > 0) { + sgemm_("N", "N", nl, k, &ctot[1], &c_b15, &u2[(u2_dim1 << 1) + 1], + ldu2, &q[q_dim1 + 2], ldq, &c_b29, &u[u_dim1 + 1], ldu); + if (ctot[3] > 0) { + ktemp = ctot[1] + 2 + ctot[2]; + sgemm_("N", "N", nl, k, &ctot[3], &c_b15, &u2[ktemp * u2_dim1 + 1] + , ldu2, &q[ktemp + q_dim1], ldq, &c_b15, &u[u_dim1 + 1], + ldu); + } + } else if (ctot[3] > 0) { + ktemp = ctot[1] + 2 + ctot[2]; + sgemm_("N", "N", nl, k, &ctot[3], &c_b15, &u2[ktemp * u2_dim1 + 1], + ldu2, &q[ktemp + q_dim1], ldq, &c_b29, &u[u_dim1 + 1], ldu); + } else { + slacpy_("F", nl, k, &u2[u2_offset], ldu2, &u[u_offset], ldu); + } + scopy_(k, &q[q_dim1 + 1], ldq, &u[nlp1 + u_dim1], ldu); + ktemp = ctot[1] + 2; + ctemp = ctot[2] + ctot[3]; + sgemm_("N", "N", nr, k, &ctemp, &c_b15, &u2[nlp2 + ktemp * u2_dim1], ldu2, + &q[ktemp + q_dim1], ldq, &c_b29, &u[nlp2 + u_dim1], ldu); + +/* Generate the right singular vectors. */ + +L100: + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + temp = snrm2_(k, &vt[i__ * vt_dim1 + 1], &c__1); + q[i__ + q_dim1] = vt[i__ * vt_dim1 + 1] / temp; + i__2 = *k; + for (j = 2; j <= i__2; ++j) { + jc = idxc[j]; + q[i__ + j * q_dim1] = vt[jc + i__ * vt_dim1] / temp; +/* L110: */ + } +/* L120: */ + } + +/* Update the right singular vector matrix. */ + + if (*k == 2) { + sgemm_("N", "N", k, &m, k, &c_b15, &q[q_offset], ldq, &vt2[vt2_offset] + , ldvt2, &c_b29, &vt[vt_offset], ldvt); + return 0; + } + ktemp = ctot[1] + 1; + sgemm_("N", "N", k, &nlp1, &ktemp, &c_b15, &q[q_dim1 + 1], ldq, &vt2[ + vt2_dim1 + 1], ldvt2, &c_b29, &vt[vt_dim1 + 1], ldvt); + ktemp = ctot[1] + 2 + ctot[2]; + if (ktemp <= *ldvt2) { + sgemm_("N", "N", k, &nlp1, &ctot[3], &c_b15, &q[ktemp * q_dim1 + 1], + ldq, &vt2[ktemp + vt2_dim1], ldvt2, &c_b15, &vt[vt_dim1 + 1], + ldvt); + } + + ktemp = ctot[1] + 1; + nrp1 = *nr + *sqre; + if (ktemp > 1) { + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + q[i__ + ktemp * q_dim1] = q[i__ + q_dim1]; +/* L130: */ + } + i__1 = m; + for (i__ = nlp2; i__ <= i__1; ++i__) { + vt2[ktemp + i__ * vt2_dim1] = vt2[i__ * vt2_dim1 + 1]; +/* L140: */ + } + } + ctemp = ctot[2] + 1 + ctot[3]; + sgemm_("N", "N", k, &nrp1, &ctemp, &c_b15, &q[ktemp * q_dim1 + 1], ldq, & + vt2[ktemp + nlp2 * vt2_dim1], ldvt2, &c_b29, &vt[nlp2 * vt_dim1 + + 1], ldvt); + + return 0; + +/* End of SLASD3 */ + +} /* slasd3_ */ + +/* Subroutine */ int slasd4_(integer *n, integer *i__, real *d__, real *z__, + real *delta, real *rho, real *sigma, real *work, integer *info) +{ + /* System generated locals */ + integer i__1; + real r__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real a, b, c__; + static integer j; + static real w, dd[3]; + static integer ii; + static real dw, zz[3]; + static integer ip1; + static real eta, phi, eps, tau, psi; + static integer iim1, iip1; + static real dphi, dpsi; + static integer iter; + static real temp, prew, sg2lb, sg2ub, temp1, temp2, dtiim, delsq, dtiip; + static integer niter; + static real dtisq; + static logical swtch; + static real dtnsq; + extern /* Subroutine */ int slaed6_(integer *, logical *, real *, real *, + real *, real *, real *, integer *); + static real delsq2; + extern /* Subroutine */ int slasd5_(integer *, real *, real *, real *, + real *, real *, real *); + static real dtnsq1; + static logical swtch3; + extern doublereal slamch_(char *); + static logical orgati; + static real erretm, dtipsq, rhoinv; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + October 31, 1999 + + + Purpose + ======= + + This subroutine computes the square root of the I-th updated + eigenvalue of a positive symmetric rank-one modification to + a positive diagonal matrix whose entries are given as the squares + of the corresponding entries in the array d, and that + + 0 <= D(i) < D(j) for i < j + + and that RHO > 0. This is arranged by the calling routine, and is + no loss in generality. The rank-one modified system is thus + + diag( D ) * diag( D ) + RHO * Z * Z_transpose. + + where we assume the Euclidean norm of Z is 1. + + The method consists of approximating the rational functions in the + secular equation by simpler interpolating rational functions. + + Arguments + ========= + + N (input) INTEGER + The length of all arrays. + + I (input) INTEGER + The index of the eigenvalue to be computed. 1 <= I <= N. + + D (input) REAL array, dimension ( N ) + The original eigenvalues. It is assumed that they are in + order, 0 <= D(I) < D(J) for I < J. + + Z (input) REAL array, dimension ( N ) + The components of the updating vector. + + DELTA (output) REAL array, dimension ( N ) + If N .ne. 1, DELTA contains (D(j) - sigma_I) in its j-th + component. If N = 1, then DELTA(1) = 1. The vector DELTA + contains the information necessary to construct the + (singular) eigenvectors. + + RHO (input) REAL + The scalar in the symmetric updating formula. + + SIGMA (output) REAL + The computed lambda_I, the I-th updated eigenvalue. + + WORK (workspace) REAL array, dimension ( N ) + If N .ne. 1, WORK contains (D(j) + sigma_I) in its j-th + component. If N = 1, then WORK( 1 ) = 1. + + INFO (output) INTEGER + = 0: successful exit + > 0: if INFO = 1, the updating process failed. + + Internal Parameters + =================== + + Logical variable ORGATI (origin-at-i?) is used for distinguishing + whether D(i) or D(i+1) is treated as the origin. + + ORGATI = .true. origin at i + ORGATI = .false. origin at i+1 + + Logical variable SWTCH3 (switch-for-3-poles?) is for noting + if we are working with THREE poles! + + MAXIT is the maximum number of iterations allowed for each + eigenvalue. + + Further Details + =============== + + Based on contributions by + Ren-Cang Li, Computer Science Division, University of California + at Berkeley, USA + + ===================================================================== + + + Since this routine is called in an inner loop, we do no argument + checking. + + Quick return for N=1 and 2. +*/ + + /* Parameter adjustments */ + --work; + --delta; + --z__; + --d__; + + /* Function Body */ + *info = 0; + if (*n == 1) { + +/* Presumably, I=1 upon entry */ + + *sigma = sqrt(d__[1] * d__[1] + *rho * z__[1] * z__[1]); + delta[1] = 1.f; + work[1] = 1.f; + return 0; + } + if (*n == 2) { + slasd5_(i__, &d__[1], &z__[1], &delta[1], rho, sigma, &work[1]); + return 0; + } + +/* Compute machine epsilon */ + + eps = slamch_("Epsilon"); + rhoinv = 1.f / *rho; + +/* The case I = N */ + + if (*i__ == *n) { + +/* Initialize some basic variables */ + + ii = *n - 1; + niter = 1; + +/* Calculate initial guess */ + + temp = *rho / 2.f; + +/* + If ||Z||_2 is not one, then TEMP should be set to + RHO * ||Z||_2^2 / TWO +*/ + + temp1 = temp / (d__[*n] + sqrt(d__[*n] * d__[*n] + temp)); + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] = d__[j] + d__[*n] + temp1; + delta[j] = d__[j] - d__[*n] - temp1; +/* L10: */ + } + + psi = 0.f; + i__1 = *n - 2; + for (j = 1; j <= i__1; ++j) { + psi += z__[j] * z__[j] / (delta[j] * work[j]); +/* L20: */ + } + + c__ = rhoinv + psi; + w = c__ + z__[ii] * z__[ii] / (delta[ii] * work[ii]) + z__[*n] * z__[* + n] / (delta[*n] * work[*n]); + + if (w <= 0.f) { + temp1 = sqrt(d__[*n] * d__[*n] + *rho); + temp = z__[*n - 1] * z__[*n - 1] / ((d__[*n - 1] + temp1) * (d__[* + n] - d__[*n - 1] + *rho / (d__[*n] + temp1))) + z__[*n] * + z__[*n] / *rho; + +/* + The following TAU is to approximate + SIGMA_n^2 - D( N )*D( N ) +*/ + + if (c__ <= temp) { + tau = *rho; + } else { + delsq = (d__[*n] - d__[*n - 1]) * (d__[*n] + d__[*n - 1]); + a = -c__ * delsq + z__[*n - 1] * z__[*n - 1] + z__[*n] * z__[* + n]; + b = z__[*n] * z__[*n] * delsq; + if (a < 0.f) { + tau = b * 2.f / (sqrt(a * a + b * 4.f * c__) - a); + } else { + tau = (a + sqrt(a * a + b * 4.f * c__)) / (c__ * 2.f); + } + } + +/* + It can be proved that + D(N)^2+RHO/2 <= SIGMA_n^2 < D(N)^2+TAU <= D(N)^2+RHO +*/ + + } else { + delsq = (d__[*n] - d__[*n - 1]) * (d__[*n] + d__[*n - 1]); + a = -c__ * delsq + z__[*n - 1] * z__[*n - 1] + z__[*n] * z__[*n]; + b = z__[*n] * z__[*n] * delsq; + +/* + The following TAU is to approximate + SIGMA_n^2 - D( N )*D( N ) +*/ + + if (a < 0.f) { + tau = b * 2.f / (sqrt(a * a + b * 4.f * c__) - a); + } else { + tau = (a + sqrt(a * a + b * 4.f * c__)) / (c__ * 2.f); + } + +/* + It can be proved that + D(N)^2 < D(N)^2+TAU < SIGMA(N)^2 < D(N)^2+RHO/2 +*/ + + } + +/* The following ETA is to approximate SIGMA_n - D( N ) */ + + eta = tau / (d__[*n] + sqrt(d__[*n] * d__[*n] + tau)); + + *sigma = d__[*n] + eta; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[*i__] - eta; + work[j] = d__[j] + d__[*i__] + eta; +/* L30: */ + } + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (delta[j] * work[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L40: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / (delta[*n] * work[*n]); + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8.f + erretm - phi + rhoinv + dabs(tau) * ( + dpsi + dphi); + + w = rhoinv + phi + psi; + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + goto L240; + } + +/* Calculate the new step */ + + ++niter; + dtnsq1 = work[*n - 1] * delta[*n - 1]; + dtnsq = work[*n] * delta[*n]; + c__ = w - dtnsq1 * dpsi - dtnsq * dphi; + a = (dtnsq + dtnsq1) * w - dtnsq * dtnsq1 * (dpsi + dphi); + b = dtnsq * dtnsq1 * w; + if (c__ < 0.f) { + c__ = dabs(c__); + } + if (c__ == 0.f) { + eta = *rho - *sigma * *sigma; + } else if (a >= 0.f) { + eta = (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / ( + c__ * 2.f); + } else { + eta = b * 2.f / (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } + +/* + Note, eta should be positive if w is negative, and + eta should be negative otherwise. However, + if for some reason caused by roundoff, eta*w > 0, + we simply use one Newton step instead. This way + will guarantee eta*w < 0. +*/ + + if (w * eta > 0.f) { + eta = -w / (dpsi + dphi); + } + temp = eta - dtnsq; + if (temp > *rho) { + eta = *rho + dtnsq; + } + + tau += eta; + eta /= *sigma + sqrt(eta + *sigma * *sigma); + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; + work[j] += eta; +/* L50: */ + } + + *sigma += eta; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (work[j] * delta[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L60: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / (work[*n] * delta[*n]); + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8.f + erretm - phi + rhoinv + dabs(tau) * ( + dpsi + dphi); + + w = rhoinv + phi + psi; + +/* Main loop to update the values of the array DELTA */ + + iter = niter + 1; + + for (niter = iter; niter <= 20; ++niter) { + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + goto L240; + } + +/* Calculate the new step */ + + dtnsq1 = work[*n - 1] * delta[*n - 1]; + dtnsq = work[*n] * delta[*n]; + c__ = w - dtnsq1 * dpsi - dtnsq * dphi; + a = (dtnsq + dtnsq1) * w - dtnsq1 * dtnsq * (dpsi + dphi); + b = dtnsq1 * dtnsq * w; + if (a >= 0.f) { + eta = (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / + (c__ * 2.f); + } else { + eta = b * 2.f / (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } + +/* + Note, eta should be positive if w is negative, and + eta should be negative otherwise. However, + if for some reason caused by roundoff, eta*w > 0, + we simply use one Newton step instead. This way + will guarantee eta*w < 0. +*/ + + if (w * eta > 0.f) { + eta = -w / (dpsi + dphi); + } + temp = eta - dtnsq; + if (temp <= 0.f) { + eta /= 2.f; + } + + tau += eta; + eta /= *sigma + sqrt(eta + *sigma * *sigma); + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; + work[j] += eta; +/* L70: */ + } + + *sigma += eta; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (work[j] * delta[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L80: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / (work[*n] * delta[*n]); + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8.f + erretm - phi + rhoinv + dabs(tau) * + (dpsi + dphi); + + w = rhoinv + phi + psi; +/* L90: */ + } + +/* Return with INFO = 1, NITER = MAXIT and not converged */ + + *info = 1; + goto L240; + +/* End for the case I = N */ + + } else { + +/* The case for I < N */ + + niter = 1; + ip1 = *i__ + 1; + +/* Calculate initial guess */ + + delsq = (d__[ip1] - d__[*i__]) * (d__[ip1] + d__[*i__]); + delsq2 = delsq / 2.f; + temp = delsq2 / (d__[*i__] + sqrt(d__[*i__] * d__[*i__] + delsq2)); + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] = d__[j] + d__[*i__] + temp; + delta[j] = d__[j] - d__[*i__] - temp; +/* L100: */ + } + + psi = 0.f; + i__1 = *i__ - 1; + for (j = 1; j <= i__1; ++j) { + psi += z__[j] * z__[j] / (work[j] * delta[j]); +/* L110: */ + } + + phi = 0.f; + i__1 = *i__ + 2; + for (j = *n; j >= i__1; --j) { + phi += z__[j] * z__[j] / (work[j] * delta[j]); +/* L120: */ + } + c__ = rhoinv + psi + phi; + w = c__ + z__[*i__] * z__[*i__] / (work[*i__] * delta[*i__]) + z__[ + ip1] * z__[ip1] / (work[ip1] * delta[ip1]); + + if (w > 0.f) { + +/* + d(i)^2 < the ith sigma^2 < (d(i)^2+d(i+1)^2)/2 + + We choose d(i) as origin. +*/ + + orgati = TRUE_; + sg2lb = 0.f; + sg2ub = delsq2; + a = c__ * delsq + z__[*i__] * z__[*i__] + z__[ip1] * z__[ip1]; + b = z__[*i__] * z__[*i__] * delsq; + if (a > 0.f) { + tau = b * 2.f / (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } else { + tau = (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / + (c__ * 2.f); + } + +/* + TAU now is an estimation of SIGMA^2 - D( I )^2. The + following, however, is the corresponding estimation of + SIGMA - D( I ). +*/ + + eta = tau / (d__[*i__] + sqrt(d__[*i__] * d__[*i__] + tau)); + } else { + +/* + (d(i)^2+d(i+1)^2)/2 <= the ith sigma^2 < d(i+1)^2/2 + + We choose d(i+1) as origin. +*/ + + orgati = FALSE_; + sg2lb = -delsq2; + sg2ub = 0.f; + a = c__ * delsq - z__[*i__] * z__[*i__] - z__[ip1] * z__[ip1]; + b = z__[ip1] * z__[ip1] * delsq; + if (a < 0.f) { + tau = b * 2.f / (a - sqrt((r__1 = a * a + b * 4.f * c__, dabs( + r__1)))); + } else { + tau = -(a + sqrt((r__1 = a * a + b * 4.f * c__, dabs(r__1)))) + / (c__ * 2.f); + } + +/* + TAU now is an estimation of SIGMA^2 - D( IP1 )^2. The + following, however, is the corresponding estimation of + SIGMA - D( IP1 ). +*/ + + eta = tau / (d__[ip1] + sqrt((r__1 = d__[ip1] * d__[ip1] + tau, + dabs(r__1)))); + } + + if (orgati) { + ii = *i__; + *sigma = d__[*i__] + eta; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] = d__[j] + d__[*i__] + eta; + delta[j] = d__[j] - d__[*i__] - eta; +/* L130: */ + } + } else { + ii = *i__ + 1; + *sigma = d__[ip1] + eta; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] = d__[j] + d__[ip1] + eta; + delta[j] = d__[j] - d__[ip1] - eta; +/* L140: */ + } + } + iim1 = ii - 1; + iip1 = ii + 1; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (work[j] * delta[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L150: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.f; + phi = 0.f; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[j] / (work[j] * delta[j]); + phi += z__[j] * temp; + dphi += temp * temp; + erretm += phi; +/* L160: */ + } + + w = rhoinv + phi + psi; + +/* + W is the value of the secular function with + its ii-th element removed. +*/ + + swtch3 = FALSE_; + if (orgati) { + if (w < 0.f) { + swtch3 = TRUE_; + } + } else { + if (w > 0.f) { + swtch3 = TRUE_; + } + } + if (ii == 1 || ii == *n) { + swtch3 = FALSE_; + } + + temp = z__[ii] / (work[ii] * delta[ii]); + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w += temp; + erretm = (phi - psi) * 8.f + erretm + rhoinv * 2.f + dabs(temp) * 3.f + + dabs(tau) * dw; + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + goto L240; + } + + if (w <= 0.f) { + sg2lb = dmax(sg2lb,tau); + } else { + sg2ub = dmin(sg2ub,tau); + } + +/* Calculate the new step */ + + ++niter; + if (! swtch3) { + dtipsq = work[ip1] * delta[ip1]; + dtisq = work[*i__] * delta[*i__]; + if (orgati) { +/* Computing 2nd power */ + r__1 = z__[*i__] / dtisq; + c__ = w - dtipsq * dw + delsq * (r__1 * r__1); + } else { +/* Computing 2nd power */ + r__1 = z__[ip1] / dtipsq; + c__ = w - dtisq * dw - delsq * (r__1 * r__1); + } + a = (dtipsq + dtisq) * w - dtipsq * dtisq * dw; + b = dtipsq * dtisq * w; + if (c__ == 0.f) { + if (a == 0.f) { + if (orgati) { + a = z__[*i__] * z__[*i__] + dtipsq * dtipsq * (dpsi + + dphi); + } else { + a = z__[ip1] * z__[ip1] + dtisq * dtisq * (dpsi + + dphi); + } + } + eta = b / a; + } else if (a <= 0.f) { + eta = (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / + (c__ * 2.f); + } else { + eta = b * 2.f / (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } + } else { + +/* Interpolation using THREE most relevant poles */ + + dtiim = work[iim1] * delta[iim1]; + dtiip = work[iip1] * delta[iip1]; + temp = rhoinv + psi + phi; + if (orgati) { + temp1 = z__[iim1] / dtiim; + temp1 *= temp1; + c__ = temp - dtiip * (dpsi + dphi) - (d__[iim1] - d__[iip1]) * + (d__[iim1] + d__[iip1]) * temp1; + zz[0] = z__[iim1] * z__[iim1]; + if (dpsi < temp1) { + zz[2] = dtiip * dtiip * dphi; + } else { + zz[2] = dtiip * dtiip * (dpsi - temp1 + dphi); + } + } else { + temp1 = z__[iip1] / dtiip; + temp1 *= temp1; + c__ = temp - dtiim * (dpsi + dphi) - (d__[iip1] - d__[iim1]) * + (d__[iim1] + d__[iip1]) * temp1; + if (dphi < temp1) { + zz[0] = dtiim * dtiim * dpsi; + } else { + zz[0] = dtiim * dtiim * (dpsi + (dphi - temp1)); + } + zz[2] = z__[iip1] * z__[iip1]; + } + zz[1] = z__[ii] * z__[ii]; + dd[0] = dtiim; + dd[1] = delta[ii] * work[ii]; + dd[2] = dtiip; + slaed6_(&niter, &orgati, &c__, dd, zz, &w, &eta, info); + if (*info != 0) { + goto L240; + } + } + +/* + Note, eta should be positive if w is negative, and + eta should be negative otherwise. However, + if for some reason caused by roundoff, eta*w > 0, + we simply use one Newton step instead. This way + will guarantee eta*w < 0. +*/ + + if (w * eta >= 0.f) { + eta = -w / dw; + } + if (orgati) { + temp1 = work[*i__] * delta[*i__]; + temp = eta - temp1; + } else { + temp1 = work[ip1] * delta[ip1]; + temp = eta - temp1; + } + if (temp > sg2ub || temp < sg2lb) { + if (w < 0.f) { + eta = (sg2ub - tau) / 2.f; + } else { + eta = (sg2lb - tau) / 2.f; + } + } + + tau += eta; + eta /= *sigma + sqrt(*sigma * *sigma + eta); + + prew = w; + + *sigma += eta; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] += eta; + delta[j] -= eta; +/* L170: */ + } + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (work[j] * delta[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L180: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.f; + phi = 0.f; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[j] / (work[j] * delta[j]); + phi += z__[j] * temp; + dphi += temp * temp; + erretm += phi; +/* L190: */ + } + + temp = z__[ii] / (work[ii] * delta[ii]); + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w = rhoinv + phi + psi + temp; + erretm = (phi - psi) * 8.f + erretm + rhoinv * 2.f + dabs(temp) * 3.f + + dabs(tau) * dw; + + if (w <= 0.f) { + sg2lb = dmax(sg2lb,tau); + } else { + sg2ub = dmin(sg2ub,tau); + } + + swtch = FALSE_; + if (orgati) { + if (-w > dabs(prew) / 10.f) { + swtch = TRUE_; + } + } else { + if (w > dabs(prew) / 10.f) { + swtch = TRUE_; + } + } + +/* Main loop to update the values of the array DELTA and WORK */ + + iter = niter + 1; + + for (niter = iter; niter <= 20; ++niter) { + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + goto L240; + } + +/* Calculate the new step */ + + if (! swtch3) { + dtipsq = work[ip1] * delta[ip1]; + dtisq = work[*i__] * delta[*i__]; + if (! swtch) { + if (orgati) { +/* Computing 2nd power */ + r__1 = z__[*i__] / dtisq; + c__ = w - dtipsq * dw + delsq * (r__1 * r__1); + } else { +/* Computing 2nd power */ + r__1 = z__[ip1] / dtipsq; + c__ = w - dtisq * dw - delsq * (r__1 * r__1); + } + } else { + temp = z__[ii] / (work[ii] * delta[ii]); + if (orgati) { + dpsi += temp * temp; + } else { + dphi += temp * temp; + } + c__ = w - dtisq * dpsi - dtipsq * dphi; + } + a = (dtipsq + dtisq) * w - dtipsq * dtisq * dw; + b = dtipsq * dtisq * w; + if (c__ == 0.f) { + if (a == 0.f) { + if (! swtch) { + if (orgati) { + a = z__[*i__] * z__[*i__] + dtipsq * dtipsq * + (dpsi + dphi); + } else { + a = z__[ip1] * z__[ip1] + dtisq * dtisq * ( + dpsi + dphi); + } + } else { + a = dtisq * dtisq * dpsi + dtipsq * dtipsq * dphi; + } + } + eta = b / a; + } else if (a <= 0.f) { + eta = (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)) + )) / (c__ * 2.f); + } else { + eta = b * 2.f / (a + sqrt((r__1 = a * a - b * 4.f * c__, + dabs(r__1)))); + } + } else { + +/* Interpolation using THREE most relevant poles */ + + dtiim = work[iim1] * delta[iim1]; + dtiip = work[iip1] * delta[iip1]; + temp = rhoinv + psi + phi; + if (swtch) { + c__ = temp - dtiim * dpsi - dtiip * dphi; + zz[0] = dtiim * dtiim * dpsi; + zz[2] = dtiip * dtiip * dphi; + } else { + if (orgati) { + temp1 = z__[iim1] / dtiim; + temp1 *= temp1; + temp2 = (d__[iim1] - d__[iip1]) * (d__[iim1] + d__[ + iip1]) * temp1; + c__ = temp - dtiip * (dpsi + dphi) - temp2; + zz[0] = z__[iim1] * z__[iim1]; + if (dpsi < temp1) { + zz[2] = dtiip * dtiip * dphi; + } else { + zz[2] = dtiip * dtiip * (dpsi - temp1 + dphi); + } + } else { + temp1 = z__[iip1] / dtiip; + temp1 *= temp1; + temp2 = (d__[iip1] - d__[iim1]) * (d__[iim1] + d__[ + iip1]) * temp1; + c__ = temp - dtiim * (dpsi + dphi) - temp2; + if (dphi < temp1) { + zz[0] = dtiim * dtiim * dpsi; + } else { + zz[0] = dtiim * dtiim * (dpsi + (dphi - temp1)); + } + zz[2] = z__[iip1] * z__[iip1]; + } + } + dd[0] = dtiim; + dd[1] = delta[ii] * work[ii]; + dd[2] = dtiip; + slaed6_(&niter, &orgati, &c__, dd, zz, &w, &eta, info); + if (*info != 0) { + goto L240; + } + } + +/* + Note, eta should be positive if w is negative, and + eta should be negative otherwise. However, + if for some reason caused by roundoff, eta*w > 0, + we simply use one Newton step instead. This way + will guarantee eta*w < 0. +*/ + + if (w * eta >= 0.f) { + eta = -w / dw; + } + if (orgati) { + temp1 = work[*i__] * delta[*i__]; + temp = eta - temp1; + } else { + temp1 = work[ip1] * delta[ip1]; + temp = eta - temp1; + } + if (temp > sg2ub || temp < sg2lb) { + if (w < 0.f) { + eta = (sg2ub - tau) / 2.f; + } else { + eta = (sg2lb - tau) / 2.f; + } + } + + tau += eta; + eta /= *sigma + sqrt(*sigma * *sigma + eta); + + *sigma += eta; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] += eta; + delta[j] -= eta; +/* L200: */ + } + + prew = w; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (work[j] * delta[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L210: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.f; + phi = 0.f; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[j] / (work[j] * delta[j]); + phi += z__[j] * temp; + dphi += temp * temp; + erretm += phi; +/* L220: */ + } + + temp = z__[ii] / (work[ii] * delta[ii]); + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w = rhoinv + phi + psi + temp; + erretm = (phi - psi) * 8.f + erretm + rhoinv * 2.f + dabs(temp) * + 3.f + dabs(tau) * dw; + if (w * prew > 0.f && dabs(w) > dabs(prew) / 10.f) { + swtch = ! swtch; + } + + if (w <= 0.f) { + sg2lb = dmax(sg2lb,tau); + } else { + sg2ub = dmin(sg2ub,tau); + } + +/* L230: */ + } + +/* Return with INFO = 1, NITER = MAXIT and not converged */ + + *info = 1; + + } + +L240: + return 0; + +/* End of SLASD4 */ + +} /* slasd4_ */ + +/* Subroutine */ int slasd5_(integer *i__, real *d__, real *z__, real *delta, + real *rho, real *dsigma, real *work) +{ + /* System generated locals */ + real r__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real b, c__, w, del, tau, delsq; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + June 30, 1999 + + + Purpose + ======= + + This subroutine computes the square root of the I-th eigenvalue + of a positive symmetric rank-one modification of a 2-by-2 diagonal + matrix + + diag( D ) * diag( D ) + RHO * Z * transpose(Z) . + + The diagonal entries in the array D are assumed to satisfy + + 0 <= D(i) < D(j) for i < j . + + We also assume RHO > 0 and that the Euclidean norm of the vector + Z is one. + + Arguments + ========= + + I (input) INTEGER + The index of the eigenvalue to be computed. I = 1 or I = 2. + + D (input) REAL array, dimension ( 2 ) + The original eigenvalues. We assume 0 <= D(1) < D(2). + + Z (input) REAL array, dimension ( 2 ) + The components of the updating vector. + + DELTA (output) REAL array, dimension ( 2 ) + Contains (D(j) - lambda_I) in its j-th component. + The vector DELTA contains the information necessary + to construct the eigenvectors. + + RHO (input) REAL + The scalar in the symmetric updating formula. + + DSIGMA (output) REAL + The computed lambda_I, the I-th updated eigenvalue. + + WORK (workspace) REAL array, dimension ( 2 ) + WORK contains (D(j) + sigma_I) in its j-th component. + + Further Details + =============== + + Based on contributions by + Ren-Cang Li, Computer Science Division, University of California + at Berkeley, USA + + ===================================================================== +*/ + + + /* Parameter adjustments */ + --work; + --delta; + --z__; + --d__; + + /* Function Body */ + del = d__[2] - d__[1]; + delsq = del * (d__[2] + d__[1]); + if (*i__ == 1) { + w = *rho * 4.f * (z__[2] * z__[2] / (d__[1] + d__[2] * 3.f) - z__[1] * + z__[1] / (d__[1] * 3.f + d__[2])) / del + 1.f; + if (w > 0.f) { + b = delsq + *rho * (z__[1] * z__[1] + z__[2] * z__[2]); + c__ = *rho * z__[1] * z__[1] * delsq; + +/* + B > ZERO, always + + The following TAU is DSIGMA * DSIGMA - D( 1 ) * D( 1 ) +*/ + + tau = c__ * 2.f / (b + sqrt((r__1 = b * b - c__ * 4.f, dabs(r__1)) + )); + +/* The following TAU is DSIGMA - D( 1 ) */ + + tau /= d__[1] + sqrt(d__[1] * d__[1] + tau); + *dsigma = d__[1] + tau; + delta[1] = -tau; + delta[2] = del - tau; + work[1] = d__[1] * 2.f + tau; + work[2] = d__[1] + tau + d__[2]; +/* + DELTA( 1 ) = -Z( 1 ) / TAU + DELTA( 2 ) = Z( 2 ) / ( DEL-TAU ) +*/ + } else { + b = -delsq + *rho * (z__[1] * z__[1] + z__[2] * z__[2]); + c__ = *rho * z__[2] * z__[2] * delsq; + +/* The following TAU is DSIGMA * DSIGMA - D( 2 ) * D( 2 ) */ + + if (b > 0.f) { + tau = c__ * -2.f / (b + sqrt(b * b + c__ * 4.f)); + } else { + tau = (b - sqrt(b * b + c__ * 4.f)) / 2.f; + } + +/* The following TAU is DSIGMA - D( 2 ) */ + + tau /= d__[2] + sqrt((r__1 = d__[2] * d__[2] + tau, dabs(r__1))); + *dsigma = d__[2] + tau; + delta[1] = -(del + tau); + delta[2] = -tau; + work[1] = d__[1] + tau + d__[2]; + work[2] = d__[2] * 2.f + tau; +/* + DELTA( 1 ) = -Z( 1 ) / ( DEL+TAU ) + DELTA( 2 ) = -Z( 2 ) / TAU +*/ + } +/* + TEMP = SQRT( DELTA( 1 )*DELTA( 1 )+DELTA( 2 )*DELTA( 2 ) ) + DELTA( 1 ) = DELTA( 1 ) / TEMP + DELTA( 2 ) = DELTA( 2 ) / TEMP +*/ + } else { + +/* Now I=2 */ + + b = -delsq + *rho * (z__[1] * z__[1] + z__[2] * z__[2]); + c__ = *rho * z__[2] * z__[2] * delsq; + +/* The following TAU is DSIGMA * DSIGMA - D( 2 ) * D( 2 ) */ + + if (b > 0.f) { + tau = (b + sqrt(b * b + c__ * 4.f)) / 2.f; + } else { + tau = c__ * 2.f / (-b + sqrt(b * b + c__ * 4.f)); + } + +/* The following TAU is DSIGMA - D( 2 ) */ + + tau /= d__[2] + sqrt(d__[2] * d__[2] + tau); + *dsigma = d__[2] + tau; + delta[1] = -(del + tau); + delta[2] = -tau; + work[1] = d__[1] + tau + d__[2]; + work[2] = d__[2] * 2.f + tau; +/* + DELTA( 1 ) = -Z( 1 ) / ( DEL+TAU ) + DELTA( 2 ) = -Z( 2 ) / TAU + TEMP = SQRT( DELTA( 1 )*DELTA( 1 )+DELTA( 2 )*DELTA( 2 ) ) + DELTA( 1 ) = DELTA( 1 ) / TEMP + DELTA( 2 ) = DELTA( 2 ) / TEMP +*/ + } + return 0; + +/* End of SLASD5 */ + +} /* slasd5_ */ + +/* Subroutine */ int slasd6_(integer *icompq, integer *nl, integer *nr, + integer *sqre, real *d__, real *vf, real *vl, real *alpha, real *beta, + integer *idxq, integer *perm, integer *givptr, integer *givcol, + integer *ldgcol, real *givnum, integer *ldgnum, real *poles, real * + difl, real *difr, real *z__, integer *k, real *c__, real *s, real * + work, integer *iwork, integer *info) +{ + /* System generated locals */ + integer givcol_dim1, givcol_offset, givnum_dim1, givnum_offset, + poles_dim1, poles_offset, i__1; + real r__1, r__2; + + /* Local variables */ + static integer i__, m, n, n1, n2, iw, idx, idxc, idxp, ivfw, ivlw; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *), slasd7_(integer *, integer *, integer *, integer *, + integer *, real *, real *, real *, real *, real *, real *, real *, + real *, real *, real *, integer *, integer *, integer *, integer + *, integer *, integer *, integer *, real *, integer *, real *, + real *, integer *), slasd8_(integer *, integer *, real *, real *, + real *, real *, real *, real *, integer *, real *, real *, + integer *); + static integer isigma; + extern /* Subroutine */ int xerbla_(char *, integer *), slascl_( + char *, integer *, integer *, real *, real *, integer *, integer * + , real *, integer *, integer *), slamrg_(integer *, + integer *, real *, integer *, integer *, integer *); + static real orgnrm; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SLASD6 computes the SVD of an updated upper bidiagonal matrix B + obtained by merging two smaller ones by appending a row. This + routine is used only for the problem which requires all singular + values and optionally singular vector matrices in factored form. + B is an N-by-M matrix with N = NL + NR + 1 and M = N + SQRE. + A related subroutine, SLASD1, handles the case in which all singular + values and singular vectors of the bidiagonal matrix are desired. + + SLASD6 computes the SVD as follows: + + ( D1(in) 0 0 0 ) + B = U(in) * ( Z1' a Z2' b ) * VT(in) + ( 0 0 D2(in) 0 ) + + = U(out) * ( D(out) 0) * VT(out) + + where Z' = (Z1' a Z2' b) = u' VT', and u is a vector of dimension M + with ALPHA and BETA in the NL+1 and NL+2 th entries and zeros + elsewhere; and the entry b is empty if SQRE = 0. + + The singular values of B can be computed using D1, D2, the first + components of all the right singular vectors of the lower block, and + the last components of all the right singular vectors of the upper + block. These components are stored and updated in VF and VL, + respectively, in SLASD6. Hence U and VT are not explicitly + referenced. + + The singular values are stored in D. The algorithm consists of two + stages: + + The first stage consists of deflating the size of the problem + when there are multiple singular values or if there is a zero + in the Z vector. For each such occurence the dimension of the + secular equation problem is reduced by one. This stage is + performed by the routine SLASD7. + + The second stage consists of calculating the updated + singular values. This is done by finding the roots of the + secular equation via the routine SLASD4 (as called by SLASD8). + This routine also updates VF and VL and computes the distances + between the updated singular values and the old singular + values. + + SLASD6 is called from SLASDA. + + Arguments + ========= + + ICOMPQ (input) INTEGER + Specifies whether singular vectors are to be computed in + factored form: + = 0: Compute singular values only. + = 1: Compute singular vectors in factored form as well. + + NL (input) INTEGER + The row dimension of the upper block. NL >= 1. + + NR (input) INTEGER + The row dimension of the lower block. NR >= 1. + + SQRE (input) INTEGER + = 0: the lower block is an NR-by-NR square matrix. + = 1: the lower block is an NR-by-(NR+1) rectangular matrix. + + The bidiagonal matrix has row dimension N = NL + NR + 1, + and column dimension M = N + SQRE. + + D (input/output) REAL array, dimension ( NL+NR+1 ). + On entry D(1:NL,1:NL) contains the singular values of the + upper block, and D(NL+2:N) contains the singular values + of the lower block. On exit D(1:N) contains the singular + values of the modified matrix. + + VF (input/output) REAL array, dimension ( M ) + On entry, VF(1:NL+1) contains the first components of all + right singular vectors of the upper block; and VF(NL+2:M) + contains the first components of all right singular vectors + of the lower block. On exit, VF contains the first components + of all right singular vectors of the bidiagonal matrix. + + VL (input/output) REAL array, dimension ( M ) + On entry, VL(1:NL+1) contains the last components of all + right singular vectors of the upper block; and VL(NL+2:M) + contains the last components of all right singular vectors of + the lower block. On exit, VL contains the last components of + all right singular vectors of the bidiagonal matrix. + + ALPHA (input) REAL + Contains the diagonal element associated with the added row. + + BETA (input) REAL + Contains the off-diagonal element associated with the added + row. + + IDXQ (output) INTEGER array, dimension ( N ) + This contains the permutation which will reintegrate the + subproblem just solved back into sorted order, i.e. + D( IDXQ( I = 1, N ) ) will be in ascending order. + + PERM (output) INTEGER array, dimension ( N ) + The permutations (from deflation and sorting) to be applied + to each block. Not referenced if ICOMPQ = 0. + + GIVPTR (output) INTEGER + The number of Givens rotations which took place in this + subproblem. Not referenced if ICOMPQ = 0. + + GIVCOL (output) INTEGER array, dimension ( LDGCOL, 2 ) + Each pair of numbers indicates a pair of columns to take place + in a Givens rotation. Not referenced if ICOMPQ = 0. + + LDGCOL (input) INTEGER + leading dimension of GIVCOL, must be at least N. + + GIVNUM (output) REAL array, dimension ( LDGNUM, 2 ) + Each number indicates the C or S value to be used in the + corresponding Givens rotation. Not referenced if ICOMPQ = 0. + + LDGNUM (input) INTEGER + The leading dimension of GIVNUM and POLES, must be at least N. + + POLES (output) REAL array, dimension ( LDGNUM, 2 ) + On exit, POLES(1,*) is an array containing the new singular + values obtained from solving the secular equation, and + POLES(2,*) is an array containing the poles in the secular + equation. Not referenced if ICOMPQ = 0. + + DIFL (output) REAL array, dimension ( N ) + On exit, DIFL(I) is the distance between I-th updated + (undeflated) singular value and the I-th (undeflated) old + singular value. + + DIFR (output) REAL array, + dimension ( LDGNUM, 2 ) if ICOMPQ = 1 and + dimension ( N ) if ICOMPQ = 0. + On exit, DIFR(I, 1) is the distance between I-th updated + (undeflated) singular value and the I+1-th (undeflated) old + singular value. + + If ICOMPQ = 1, DIFR(1:K,2) is an array containing the + normalizing factors for the right singular vector matrix. + + See SLASD8 for details on DIFL and DIFR. + + Z (output) REAL array, dimension ( M ) + The first elements of this array contain the components + of the deflation-adjusted updating row vector. + + K (output) INTEGER + Contains the dimension of the non-deflated matrix, + This is the order of the related secular equation. 1 <= K <=N. + + C (output) REAL + C contains garbage if SQRE =0 and the C-value of a Givens + rotation related to the right null space if SQRE = 1. + + S (output) REAL + S contains garbage if SQRE =0 and the S-value of a Givens + rotation related to the right null space if SQRE = 1. + + WORK (workspace) REAL array, dimension ( 4 * M ) + + IWORK (workspace) INTEGER array, dimension ( 3 * N ) + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: if INFO = 1, an singular value did not converge + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --vf; + --vl; + --idxq; + --perm; + givcol_dim1 = *ldgcol; + givcol_offset = 1 + givcol_dim1; + givcol -= givcol_offset; + poles_dim1 = *ldgnum; + poles_offset = 1 + poles_dim1; + poles -= poles_offset; + givnum_dim1 = *ldgnum; + givnum_offset = 1 + givnum_dim1; + givnum -= givnum_offset; + --difl; + --difr; + --z__; + --work; + --iwork; + + /* Function Body */ + *info = 0; + n = *nl + *nr + 1; + m = n + *sqre; + + if (*icompq < 0 || *icompq > 1) { + *info = -1; + } else if (*nl < 1) { + *info = -2; + } else if (*nr < 1) { + *info = -3; + } else if (*sqre < 0 || *sqre > 1) { + *info = -4; + } else if (*ldgcol < n) { + *info = -14; + } else if (*ldgnum < n) { + *info = -16; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLASD6", &i__1); + return 0; + } + +/* + The following values are for bookkeeping purposes only. They are + integer pointers which indicate the portion of the workspace + used by a particular array in SLASD7 and SLASD8. +*/ + + isigma = 1; + iw = isigma + n; + ivfw = iw + m; + ivlw = ivfw + m; + + idx = 1; + idxc = idx + n; + idxp = idxc + n; + +/* + Scale. + + Computing MAX +*/ + r__1 = dabs(*alpha), r__2 = dabs(*beta); + orgnrm = dmax(r__1,r__2); + d__[*nl + 1] = 0.f; + i__1 = n; + for (i__ = 1; i__ <= i__1; ++i__) { + if ((r__1 = d__[i__], dabs(r__1)) > orgnrm) { + orgnrm = (r__1 = d__[i__], dabs(r__1)); + } +/* L10: */ + } + slascl_("G", &c__0, &c__0, &orgnrm, &c_b15, &n, &c__1, &d__[1], &n, info); + *alpha /= orgnrm; + *beta /= orgnrm; + +/* Sort and Deflate singular values. */ + + slasd7_(icompq, nl, nr, sqre, k, &d__[1], &z__[1], &work[iw], &vf[1], & + work[ivfw], &vl[1], &work[ivlw], alpha, beta, &work[isigma], & + iwork[idx], &iwork[idxp], &idxq[1], &perm[1], givptr, &givcol[ + givcol_offset], ldgcol, &givnum[givnum_offset], ldgnum, c__, s, + info); + +/* Solve Secular Equation, compute DIFL, DIFR, and update VF, VL. */ + + slasd8_(icompq, k, &d__[1], &z__[1], &vf[1], &vl[1], &difl[1], &difr[1], + ldgnum, &work[isigma], &work[iw], info); + +/* Save the poles if ICOMPQ = 1. */ + + if (*icompq == 1) { + scopy_(k, &d__[1], &c__1, &poles[poles_dim1 + 1], &c__1); + scopy_(k, &work[isigma], &c__1, &poles[(poles_dim1 << 1) + 1], &c__1); + } + +/* Unscale. */ + + slascl_("G", &c__0, &c__0, &c_b15, &orgnrm, &n, &c__1, &d__[1], &n, info); + +/* Prepare the IDXQ sorting permutation. */ + + n1 = *k; + n2 = n - *k; + slamrg_(&n1, &n2, &d__[1], &c__1, &c_n1, &idxq[1]); + + return 0; + +/* End of SLASD6 */ + +} /* slasd6_ */ + +/* Subroutine */ int slasd7_(integer *icompq, integer *nl, integer *nr, + integer *sqre, integer *k, real *d__, real *z__, real *zw, real *vf, + real *vfw, real *vl, real *vlw, real *alpha, real *beta, real *dsigma, + integer *idx, integer *idxp, integer *idxq, integer *perm, integer * + givptr, integer *givcol, integer *ldgcol, real *givnum, integer * + ldgnum, real *c__, real *s, integer *info) +{ + /* System generated locals */ + integer givcol_dim1, givcol_offset, givnum_dim1, givnum_offset, i__1; + real r__1, r__2; + + /* Local variables */ + static integer i__, j, m, n, k2; + static real z1; + static integer jp; + static real eps, tau, tol; + static integer nlp1, nlp2, idxi, idxj; + extern /* Subroutine */ int srot_(integer *, real *, integer *, real *, + integer *, real *, real *); + static integer idxjp, jprev; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *); + extern doublereal slapy2_(real *, real *), slamch_(char *); + extern /* Subroutine */ int xerbla_(char *, integer *), slamrg_( + integer *, integer *, real *, integer *, integer *, integer *); + static real hlftol; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + June 30, 1999 + + + Purpose + ======= + + SLASD7 merges the two sets of singular values together into a single + sorted set. Then it tries to deflate the size of the problem. There + are two ways in which deflation can occur: when two or more singular + values are close together or if there is a tiny entry in the Z + vector. For each such occurrence the order of the related + secular equation problem is reduced by one. + + SLASD7 is called from SLASD6. + + Arguments + ========= + + ICOMPQ (input) INTEGER + Specifies whether singular vectors are to be computed + in compact form, as follows: + = 0: Compute singular values only. + = 1: Compute singular vectors of upper + bidiagonal matrix in compact form. + + NL (input) INTEGER + The row dimension of the upper block. NL >= 1. + + NR (input) INTEGER + The row dimension of the lower block. NR >= 1. + + SQRE (input) INTEGER + = 0: the lower block is an NR-by-NR square matrix. + = 1: the lower block is an NR-by-(NR+1) rectangular matrix. + + The bidiagonal matrix has + N = NL + NR + 1 rows and + M = N + SQRE >= N columns. + + K (output) INTEGER + Contains the dimension of the non-deflated matrix, this is + the order of the related secular equation. 1 <= K <=N. + + D (input/output) REAL array, dimension ( N ) + On entry D contains the singular values of the two submatrices + to be combined. On exit D contains the trailing (N-K) updated + singular values (those which were deflated) sorted into + increasing order. + + Z (output) REAL array, dimension ( M ) + On exit Z contains the updating row vector in the secular + equation. + + ZW (workspace) REAL array, dimension ( M ) + Workspace for Z. + + VF (input/output) REAL array, dimension ( M ) + On entry, VF(1:NL+1) contains the first components of all + right singular vectors of the upper block; and VF(NL+2:M) + contains the first components of all right singular vectors + of the lower block. On exit, VF contains the first components + of all right singular vectors of the bidiagonal matrix. + + VFW (workspace) REAL array, dimension ( M ) + Workspace for VF. + + VL (input/output) REAL array, dimension ( M ) + On entry, VL(1:NL+1) contains the last components of all + right singular vectors of the upper block; and VL(NL+2:M) + contains the last components of all right singular vectors + of the lower block. On exit, VL contains the last components + of all right singular vectors of the bidiagonal matrix. + + VLW (workspace) REAL array, dimension ( M ) + Workspace for VL. + + ALPHA (input) REAL + Contains the diagonal element associated with the added row. + + BETA (input) REAL + Contains the off-diagonal element associated with the added + row. + + DSIGMA (output) REAL array, dimension ( N ) + Contains a copy of the diagonal elements (K-1 singular values + and one zero) in the secular equation. + + IDX (workspace) INTEGER array, dimension ( N ) + This will contain the permutation used to sort the contents of + D into ascending order. + + IDXP (workspace) INTEGER array, dimension ( N ) + This will contain the permutation used to place deflated + values of D at the end of the array. On output IDXP(2:K) + points to the nondeflated D-values and IDXP(K+1:N) + points to the deflated singular values. + + IDXQ (input) INTEGER array, dimension ( N ) + This contains the permutation which separately sorts the two + sub-problems in D into ascending order. Note that entries in + the first half of this permutation must first be moved one + position backward; and entries in the second half + must first have NL+1 added to their values. + + PERM (output) INTEGER array, dimension ( N ) + The permutations (from deflation and sorting) to be applied + to each singular block. Not referenced if ICOMPQ = 0. + + GIVPTR (output) INTEGER + The number of Givens rotations which took place in this + subproblem. Not referenced if ICOMPQ = 0. + + GIVCOL (output) INTEGER array, dimension ( LDGCOL, 2 ) + Each pair of numbers indicates a pair of columns to take place + in a Givens rotation. Not referenced if ICOMPQ = 0. + + LDGCOL (input) INTEGER + The leading dimension of GIVCOL, must be at least N. + + GIVNUM (output) REAL array, dimension ( LDGNUM, 2 ) + Each number indicates the C or S value to be used in the + corresponding Givens rotation. Not referenced if ICOMPQ = 0. + + LDGNUM (input) INTEGER + The leading dimension of GIVNUM, must be at least N. + + C (output) REAL + C contains garbage if SQRE =0 and the C-value of a Givens + rotation related to the right null space if SQRE = 1. + + S (output) REAL + S contains garbage if SQRE =0 and the S-value of a Givens + rotation related to the right null space if SQRE = 1. + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --z__; + --zw; + --vf; + --vfw; + --vl; + --vlw; + --dsigma; + --idx; + --idxp; + --idxq; + --perm; + givcol_dim1 = *ldgcol; + givcol_offset = 1 + givcol_dim1; + givcol -= givcol_offset; + givnum_dim1 = *ldgnum; + givnum_offset = 1 + givnum_dim1; + givnum -= givnum_offset; + + /* Function Body */ + *info = 0; + n = *nl + *nr + 1; + m = n + *sqre; + + if (*icompq < 0 || *icompq > 1) { + *info = -1; + } else if (*nl < 1) { + *info = -2; + } else if (*nr < 1) { + *info = -3; + } else if (*sqre < 0 || *sqre > 1) { + *info = -4; + } else if (*ldgcol < n) { + *info = -22; + } else if (*ldgnum < n) { + *info = -24; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLASD7", &i__1); + return 0; + } + + nlp1 = *nl + 1; + nlp2 = *nl + 2; + if (*icompq == 1) { + *givptr = 0; + } + +/* + Generate the first part of the vector Z and move the singular + values in the first part of D one position backward. +*/ + + z1 = *alpha * vl[nlp1]; + vl[nlp1] = 0.f; + tau = vf[nlp1]; + for (i__ = *nl; i__ >= 1; --i__) { + z__[i__ + 1] = *alpha * vl[i__]; + vl[i__] = 0.f; + vf[i__ + 1] = vf[i__]; + d__[i__ + 1] = d__[i__]; + idxq[i__ + 1] = idxq[i__] + 1; +/* L10: */ + } + vf[1] = tau; + +/* Generate the second part of the vector Z. */ + + i__1 = m; + for (i__ = nlp2; i__ <= i__1; ++i__) { + z__[i__] = *beta * vf[i__]; + vf[i__] = 0.f; +/* L20: */ + } + +/* Sort the singular values into increasing order */ + + i__1 = n; + for (i__ = nlp2; i__ <= i__1; ++i__) { + idxq[i__] += nlp1; +/* L30: */ + } + +/* DSIGMA, IDXC, IDXC, and ZW are used as storage space. */ + + i__1 = n; + for (i__ = 2; i__ <= i__1; ++i__) { + dsigma[i__] = d__[idxq[i__]]; + zw[i__] = z__[idxq[i__]]; + vfw[i__] = vf[idxq[i__]]; + vlw[i__] = vl[idxq[i__]]; +/* L40: */ + } + + slamrg_(nl, nr, &dsigma[2], &c__1, &c__1, &idx[2]); + + i__1 = n; + for (i__ = 2; i__ <= i__1; ++i__) { + idxi = idx[i__] + 1; + d__[i__] = dsigma[idxi]; + z__[i__] = zw[idxi]; + vf[i__] = vfw[idxi]; + vl[i__] = vlw[idxi]; +/* L50: */ + } + +/* Calculate the allowable deflation tolerence */ + + eps = slamch_("Epsilon"); +/* Computing MAX */ + r__1 = dabs(*alpha), r__2 = dabs(*beta); + tol = dmax(r__1,r__2); +/* Computing MAX */ + r__2 = (r__1 = d__[n], dabs(r__1)); + tol = eps * 64.f * dmax(r__2,tol); + +/* + There are 2 kinds of deflation -- first a value in the z-vector + is small, second two (or more) singular values are very close + together (their difference is small). + + If the value in the z-vector is small, we simply permute the + array so that the corresponding singular value is moved to the + end. + + If two values in the D-vector are close, we perform a two-sided + rotation designed to make one of the corresponding z-vector + entries zero, and then permute the array so that the deflated + singular value is moved to the end. + + If there are multiple singular values then the problem deflates. + Here the number of equal singular values are found. As each equal + singular value is found, an elementary reflector is computed to + rotate the corresponding singular subspace so that the + corresponding components of Z are zero in this new basis. +*/ + + *k = 1; + k2 = n + 1; + i__1 = n; + for (j = 2; j <= i__1; ++j) { + if ((r__1 = z__[j], dabs(r__1)) <= tol) { + +/* Deflate due to small z component. */ + + --k2; + idxp[k2] = j; + if (j == n) { + goto L100; + } + } else { + jprev = j; + goto L70; + } +/* L60: */ + } +L70: + j = jprev; +L80: + ++j; + if (j > n) { + goto L90; + } + if ((r__1 = z__[j], dabs(r__1)) <= tol) { + +/* Deflate due to small z component. */ + + --k2; + idxp[k2] = j; + } else { + +/* Check if singular values are close enough to allow deflation. */ + + if ((r__1 = d__[j] - d__[jprev], dabs(r__1)) <= tol) { + +/* Deflation is possible. */ + + *s = z__[jprev]; + *c__ = z__[j]; + +/* + Find sqrt(a**2+b**2) without overflow or + destructive underflow. +*/ + + tau = slapy2_(c__, s); + z__[j] = tau; + z__[jprev] = 0.f; + *c__ /= tau; + *s = -(*s) / tau; + +/* Record the appropriate Givens rotation */ + + if (*icompq == 1) { + ++(*givptr); + idxjp = idxq[idx[jprev] + 1]; + idxj = idxq[idx[j] + 1]; + if (idxjp <= nlp1) { + --idxjp; + } + if (idxj <= nlp1) { + --idxj; + } + givcol[*givptr + (givcol_dim1 << 1)] = idxjp; + givcol[*givptr + givcol_dim1] = idxj; + givnum[*givptr + (givnum_dim1 << 1)] = *c__; + givnum[*givptr + givnum_dim1] = *s; + } + srot_(&c__1, &vf[jprev], &c__1, &vf[j], &c__1, c__, s); + srot_(&c__1, &vl[jprev], &c__1, &vl[j], &c__1, c__, s); + --k2; + idxp[k2] = jprev; + jprev = j; + } else { + ++(*k); + zw[*k] = z__[jprev]; + dsigma[*k] = d__[jprev]; + idxp[*k] = jprev; + jprev = j; + } + } + goto L80; +L90: + +/* Record the last singular value. */ + + ++(*k); + zw[*k] = z__[jprev]; + dsigma[*k] = d__[jprev]; + idxp[*k] = jprev; + +L100: + +/* + Sort the singular values into DSIGMA. The singular values which + were not deflated go into the first K slots of DSIGMA, except + that DSIGMA(1) is treated separately. +*/ + + i__1 = n; + for (j = 2; j <= i__1; ++j) { + jp = idxp[j]; + dsigma[j] = d__[jp]; + vfw[j] = vf[jp]; + vlw[j] = vl[jp]; +/* L110: */ + } + if (*icompq == 1) { + i__1 = n; + for (j = 2; j <= i__1; ++j) { + jp = idxp[j]; + perm[j] = idxq[idx[jp] + 1]; + if (perm[j] <= nlp1) { + --perm[j]; + } +/* L120: */ + } + } + +/* + The deflated singular values go back into the last N - K slots of + D. +*/ + + i__1 = n - *k; + scopy_(&i__1, &dsigma[*k + 1], &c__1, &d__[*k + 1], &c__1); + +/* + Determine DSIGMA(1), DSIGMA(2), Z(1), VF(1), VL(1), VF(M), and + VL(M). +*/ + + dsigma[1] = 0.f; + hlftol = tol / 2.f; + if (dabs(dsigma[2]) <= hlftol) { + dsigma[2] = hlftol; + } + if (m > n) { + z__[1] = slapy2_(&z1, &z__[m]); + if (z__[1] <= tol) { + *c__ = 1.f; + *s = 0.f; + z__[1] = tol; + } else { + *c__ = z1 / z__[1]; + *s = -z__[m] / z__[1]; + } + srot_(&c__1, &vf[m], &c__1, &vf[1], &c__1, c__, s); + srot_(&c__1, &vl[m], &c__1, &vl[1], &c__1, c__, s); + } else { + if (dabs(z1) <= tol) { + z__[1] = tol; + } else { + z__[1] = z1; + } + } + +/* Restore Z, VF, and VL. */ + + i__1 = *k - 1; + scopy_(&i__1, &zw[2], &c__1, &z__[2], &c__1); + i__1 = n - 1; + scopy_(&i__1, &vfw[2], &c__1, &vf[2], &c__1); + i__1 = n - 1; + scopy_(&i__1, &vlw[2], &c__1, &vl[2], &c__1); + + return 0; + +/* End of SLASD7 */ + +} /* slasd7_ */ + +/* Subroutine */ int slasd8_(integer *icompq, integer *k, real *d__, real * + z__, real *vf, real *vl, real *difl, real *difr, integer *lddifr, + real *dsigma, real *work, integer *info) +{ + /* System generated locals */ + integer difr_dim1, difr_offset, i__1, i__2; + real r__1, r__2; + + /* Builtin functions */ + double sqrt(doublereal), r_sign(real *, real *); + + /* Local variables */ + static integer i__, j; + static real dj, rho; + static integer iwk1, iwk2, iwk3; + static real temp; + extern doublereal sdot_(integer *, real *, integer *, real *, integer *); + static integer iwk2i, iwk3i; + extern doublereal snrm2_(integer *, real *, integer *); + static real diflj, difrj, dsigj; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *); + extern doublereal slamc3_(real *, real *); + extern /* Subroutine */ int slasd4_(integer *, integer *, real *, real *, + real *, real *, real *, real *, integer *), xerbla_(char *, + integer *); + static real dsigjp; + extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *, + real *, integer *, integer *, real *, integer *, integer *), slaset_(char *, integer *, integer *, real *, real *, + real *, integer *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Oak Ridge National Lab, Argonne National Lab, + Courant Institute, NAG Ltd., and Rice University + June 30, 1999 + + + Purpose + ======= + + SLASD8 finds the square roots of the roots of the secular equation, + as defined by the values in DSIGMA and Z. It makes the appropriate + calls to SLASD4, and stores, for each element in D, the distance + to its two nearest poles (elements in DSIGMA). It also updates + the arrays VF and VL, the first and last components of all the + right singular vectors of the original bidiagonal matrix. + + SLASD8 is called from SLASD6. + + Arguments + ========= + + ICOMPQ (input) INTEGER + Specifies whether singular vectors are to be computed in + factored form in the calling routine: + = 0: Compute singular values only. + = 1: Compute singular vectors in factored form as well. + + K (input) INTEGER + The number of terms in the rational function to be solved + by SLASD4. K >= 1. + + D (output) REAL array, dimension ( K ) + On output, D contains the updated singular values. + + Z (input) REAL array, dimension ( K ) + The first K elements of this array contain the components + of the deflation-adjusted updating row vector. + + VF (input/output) REAL array, dimension ( K ) + On entry, VF contains information passed through DBEDE8. + On exit, VF contains the first K components of the first + components of all right singular vectors of the bidiagonal + matrix. + + VL (input/output) REAL array, dimension ( K ) + On entry, VL contains information passed through DBEDE8. + On exit, VL contains the first K components of the last + components of all right singular vectors of the bidiagonal + matrix. + + DIFL (output) REAL array, dimension ( K ) + On exit, DIFL(I) = D(I) - DSIGMA(I). + + DIFR (output) REAL array, + dimension ( LDDIFR, 2 ) if ICOMPQ = 1 and + dimension ( K ) if ICOMPQ = 0. + On exit, DIFR(I,1) = D(I) - DSIGMA(I+1), DIFR(K,1) is not + defined and will not be referenced. + + If ICOMPQ = 1, DIFR(1:K,2) is an array containing the + normalizing factors for the right singular vector matrix. + + LDDIFR (input) INTEGER + The leading dimension of DIFR, must be at least K. + + DSIGMA (input) REAL array, dimension ( K ) + The first K elements of this array contain the old roots + of the deflated updating problem. These are the poles + of the secular equation. + + WORK (workspace) REAL array, dimension at least 3 * K + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: if INFO = 1, an singular value did not converge + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --z__; + --vf; + --vl; + --difl; + difr_dim1 = *lddifr; + difr_offset = 1 + difr_dim1; + difr -= difr_offset; + --dsigma; + --work; + + /* Function Body */ + *info = 0; + + if (*icompq < 0 || *icompq > 1) { + *info = -1; + } else if (*k < 1) { + *info = -2; + } else if (*lddifr < *k) { + *info = -9; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLASD8", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*k == 1) { + d__[1] = dabs(z__[1]); + difl[1] = d__[1]; + if (*icompq == 1) { + difl[2] = 1.f; + difr[(difr_dim1 << 1) + 1] = 1.f; + } + return 0; + } + +/* + Modify values DSIGMA(i) to make sure all DSIGMA(i)-DSIGMA(j) can + be computed with high relative accuracy (barring over/underflow). + This is a problem on machines without a guard digit in + add/subtract (Cray XMP, Cray YMP, Cray C 90 and Cray 2). + The following code replaces DSIGMA(I) by 2*DSIGMA(I)-DSIGMA(I), + which on any of these machines zeros out the bottommost + bit of DSIGMA(I) if it is 1; this makes the subsequent + subtractions DSIGMA(I)-DSIGMA(J) unproblematic when cancellation + occurs. On binary machines with a guard digit (almost all + machines) it does not change DSIGMA(I) at all. On hexadecimal + and decimal machines with a guard digit, it slightly + changes the bottommost bits of DSIGMA(I). It does not account + for hexadecimal or decimal machines without guard digits + (we know of none). We use a subroutine call to compute + 2*DLAMBDA(I) to prevent optimizing compilers from eliminating + this code. +*/ + + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + dsigma[i__] = slamc3_(&dsigma[i__], &dsigma[i__]) - dsigma[i__]; +/* L10: */ + } + +/* Book keeping. */ + + iwk1 = 1; + iwk2 = iwk1 + *k; + iwk3 = iwk2 + *k; + iwk2i = iwk2 - 1; + iwk3i = iwk3 - 1; + +/* Normalize Z. */ + + rho = snrm2_(k, &z__[1], &c__1); + slascl_("G", &c__0, &c__0, &rho, &c_b15, k, &c__1, &z__[1], k, info); + rho *= rho; + +/* Initialize WORK(IWK3). */ + + slaset_("A", k, &c__1, &c_b15, &c_b15, &work[iwk3], k); + +/* + Compute the updated singular values, the arrays DIFL, DIFR, + and the updated Z. +*/ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + slasd4_(k, &j, &dsigma[1], &z__[1], &work[iwk1], &rho, &d__[j], &work[ + iwk2], info); + +/* If the root finder fails, the computation is terminated. */ + + if (*info != 0) { + return 0; + } + work[iwk3i + j] = work[iwk3i + j] * work[j] * work[iwk2i + j]; + difl[j] = -work[j]; + difr[j + difr_dim1] = -work[j + 1]; + i__2 = j - 1; + for (i__ = 1; i__ <= i__2; ++i__) { + work[iwk3i + i__] = work[iwk3i + i__] * work[i__] * work[iwk2i + + i__] / (dsigma[i__] - dsigma[j]) / (dsigma[i__] + dsigma[ + j]); +/* L20: */ + } + i__2 = *k; + for (i__ = j + 1; i__ <= i__2; ++i__) { + work[iwk3i + i__] = work[iwk3i + i__] * work[i__] * work[iwk2i + + i__] / (dsigma[i__] - dsigma[j]) / (dsigma[i__] + dsigma[ + j]); +/* L30: */ + } +/* L40: */ + } + +/* Compute updated Z. */ + + i__1 = *k; + for (i__ = 1; i__ <= i__1; ++i__) { + r__2 = sqrt((r__1 = work[iwk3i + i__], dabs(r__1))); + z__[i__] = r_sign(&r__2, &z__[i__]); +/* L50: */ + } + +/* Update VF and VL. */ + + i__1 = *k; + for (j = 1; j <= i__1; ++j) { + diflj = difl[j]; + dj = d__[j]; + dsigj = -dsigma[j]; + if (j < *k) { + difrj = -difr[j + difr_dim1]; + dsigjp = -dsigma[j + 1]; + } + work[j] = -z__[j] / diflj / (dsigma[j] + dj); + i__2 = j - 1; + for (i__ = 1; i__ <= i__2; ++i__) { + work[i__] = z__[i__] / (slamc3_(&dsigma[i__], &dsigj) - diflj) / ( + dsigma[i__] + dj); +/* L60: */ + } + i__2 = *k; + for (i__ = j + 1; i__ <= i__2; ++i__) { + work[i__] = z__[i__] / (slamc3_(&dsigma[i__], &dsigjp) + difrj) / + (dsigma[i__] + dj); +/* L70: */ + } + temp = snrm2_(k, &work[1], &c__1); + work[iwk2i + j] = sdot_(k, &work[1], &c__1, &vf[1], &c__1) / temp; + work[iwk3i + j] = sdot_(k, &work[1], &c__1, &vl[1], &c__1) / temp; + if (*icompq == 1) { + difr[j + (difr_dim1 << 1)] = temp; + } +/* L80: */ + } + + scopy_(k, &work[iwk2], &c__1, &vf[1], &c__1); + scopy_(k, &work[iwk3], &c__1, &vl[1], &c__1); + + return 0; + +/* End of SLASD8 */ + +} /* slasd8_ */ + +/* Subroutine */ int slasda_(integer *icompq, integer *smlsiz, integer *n, + integer *sqre, real *d__, real *e, real *u, integer *ldu, real *vt, + integer *k, real *difl, real *difr, real *z__, real *poles, integer * + givptr, integer *givcol, integer *ldgcol, integer *perm, real *givnum, + real *c__, real *s, real *work, integer *iwork, integer *info) +{ + /* System generated locals */ + integer givcol_dim1, givcol_offset, perm_dim1, perm_offset, difl_dim1, + difl_offset, difr_dim1, difr_offset, givnum_dim1, givnum_offset, + poles_dim1, poles_offset, u_dim1, u_offset, vt_dim1, vt_offset, + z_dim1, z_offset, i__1, i__2; + + /* Builtin functions */ + integer pow_ii(integer *, integer *); + + /* Local variables */ + static integer i__, j, m, i1, ic, lf, nd, ll, nl, vf, nr, vl, im1, ncc, + nlf, nrf, vfi, iwk, vli, lvl, nru, ndb1, nlp1, lvl2, nrp1; + static real beta; + static integer idxq, nlvl; + static real alpha; + static integer inode, ndiml, ndimr, idxqi, itemp, sqrei; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *), slasd6_(integer *, integer *, integer *, integer *, + real *, real *, real *, real *, real *, integer *, integer *, + integer *, integer *, integer *, real *, integer *, real *, real * + , real *, real *, integer *, real *, real *, real *, integer *, + integer *); + static integer nwork1, nwork2; + extern /* Subroutine */ int xerbla_(char *, integer *), slasdq_( + char *, integer *, integer *, integer *, integer *, integer *, + real *, real *, real *, integer *, real *, integer *, real *, + integer *, real *, integer *), slasdt_(integer *, integer + *, integer *, integer *, integer *, integer *, integer *), + slaset_(char *, integer *, integer *, real *, real *, real *, + integer *); + static integer smlszp; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1999 + + + Purpose + ======= + + Using a divide and conquer approach, SLASDA computes the singular + value decomposition (SVD) of a real upper bidiagonal N-by-M matrix + B with diagonal D and offdiagonal E, where M = N + SQRE. The + algorithm computes the singular values in the SVD B = U * S * VT. + The orthogonal matrices U and VT are optionally computed in + compact form. + + A related subroutine, SLASD0, computes the singular values and + the singular vectors in explicit form. + + Arguments + ========= + + ICOMPQ (input) INTEGER + Specifies whether singular vectors are to be computed + in compact form, as follows + = 0: Compute singular values only. + = 1: Compute singular vectors of upper bidiagonal + matrix in compact form. + + SMLSIZ (input) INTEGER + The maximum size of the subproblems at the bottom of the + computation tree. + + N (input) INTEGER + The row dimension of the upper bidiagonal matrix. This is + also the dimension of the main diagonal array D. + + SQRE (input) INTEGER + Specifies the column dimension of the bidiagonal matrix. + = 0: The bidiagonal matrix has column dimension M = N; + = 1: The bidiagonal matrix has column dimension M = N + 1. + + D (input/output) REAL array, dimension ( N ) + On entry D contains the main diagonal of the bidiagonal + matrix. On exit D, if INFO = 0, contains its singular values. + + E (input) REAL array, dimension ( M-1 ) + Contains the subdiagonal entries of the bidiagonal matrix. + On exit, E has been destroyed. + + U (output) REAL array, + dimension ( LDU, SMLSIZ ) if ICOMPQ = 1, and not referenced + if ICOMPQ = 0. If ICOMPQ = 1, on exit, U contains the left + singular vector matrices of all subproblems at the bottom + level. + + LDU (input) INTEGER, LDU = > N. + The leading dimension of arrays U, VT, DIFL, DIFR, POLES, + GIVNUM, and Z. + + VT (output) REAL array, + dimension ( LDU, SMLSIZ+1 ) if ICOMPQ = 1, and not referenced + if ICOMPQ = 0. If ICOMPQ = 1, on exit, VT' contains the right + singular vector matrices of all subproblems at the bottom + level. + + K (output) INTEGER array, + dimension ( N ) if ICOMPQ = 1 and dimension 1 if ICOMPQ = 0. + If ICOMPQ = 1, on exit, K(I) is the dimension of the I-th + secular equation on the computation tree. + + DIFL (output) REAL array, dimension ( LDU, NLVL ), + where NLVL = floor(log_2 (N/SMLSIZ))). + + DIFR (output) REAL array, + dimension ( LDU, 2 * NLVL ) if ICOMPQ = 1 and + dimension ( N ) if ICOMPQ = 0. + If ICOMPQ = 1, on exit, DIFL(1:N, I) and DIFR(1:N, 2 * I - 1) + record distances between singular values on the I-th + level and singular values on the (I -1)-th level, and + DIFR(1:N, 2 * I ) contains the normalizing factors for + the right singular vector matrix. See SLASD8 for details. + + Z (output) REAL array, + dimension ( LDU, NLVL ) if ICOMPQ = 1 and + dimension ( N ) if ICOMPQ = 0. + The first K elements of Z(1, I) contain the components of + the deflation-adjusted updating row vector for subproblems + on the I-th level. + + POLES (output) REAL array, + dimension ( LDU, 2 * NLVL ) if ICOMPQ = 1, and not referenced + if ICOMPQ = 0. If ICOMPQ = 1, on exit, POLES(1, 2*I - 1) and + POLES(1, 2*I) contain the new and old singular values + involved in the secular equations on the I-th level. + + GIVPTR (output) INTEGER array, + dimension ( N ) if ICOMPQ = 1, and not referenced if + ICOMPQ = 0. If ICOMPQ = 1, on exit, GIVPTR( I ) records + the number of Givens rotations performed on the I-th + problem on the computation tree. + + GIVCOL (output) INTEGER array, + dimension ( LDGCOL, 2 * NLVL ) if ICOMPQ = 1, and not + referenced if ICOMPQ = 0. If ICOMPQ = 1, on exit, for each I, + GIVCOL(1, 2 *I - 1) and GIVCOL(1, 2 *I) record the locations + of Givens rotations performed on the I-th level on the + computation tree. + + LDGCOL (input) INTEGER, LDGCOL = > N. + The leading dimension of arrays GIVCOL and PERM. + + PERM (output) INTEGER array, + dimension ( LDGCOL, NLVL ) if ICOMPQ = 1, and not referenced + if ICOMPQ = 0. If ICOMPQ = 1, on exit, PERM(1, I) records + permutations done on the I-th level of the computation tree. + + GIVNUM (output) REAL array, + dimension ( LDU, 2 * NLVL ) if ICOMPQ = 1, and not + referenced if ICOMPQ = 0. If ICOMPQ = 1, on exit, for each I, + GIVNUM(1, 2 *I - 1) and GIVNUM(1, 2 *I) record the C- and S- + values of Givens rotations performed on the I-th level on + the computation tree. + + C (output) REAL array, + dimension ( N ) if ICOMPQ = 1, and dimension 1 if ICOMPQ = 0. + If ICOMPQ = 1 and the I-th subproblem is not square, on exit, + C( I ) contains the C-value of a Givens rotation related to + the right null space of the I-th subproblem. + + S (output) REAL array, dimension ( N ) if + ICOMPQ = 1, and dimension 1 if ICOMPQ = 0. If ICOMPQ = 1 + and the I-th subproblem is not square, on exit, S( I ) + contains the S-value of a Givens rotation related to + the right null space of the I-th subproblem. + + WORK (workspace) REAL array, dimension + (6 * N + (SMLSIZ + 1)*(SMLSIZ + 1)). + + IWORK (workspace) INTEGER array. + Dimension must be at least (7 * N). + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: if INFO = 1, an singular value did not converge + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --e; + givnum_dim1 = *ldu; + givnum_offset = 1 + givnum_dim1; + givnum -= givnum_offset; + poles_dim1 = *ldu; + poles_offset = 1 + poles_dim1; + poles -= poles_offset; + z_dim1 = *ldu; + z_offset = 1 + z_dim1; + z__ -= z_offset; + difr_dim1 = *ldu; + difr_offset = 1 + difr_dim1; + difr -= difr_offset; + difl_dim1 = *ldu; + difl_offset = 1 + difl_dim1; + difl -= difl_offset; + vt_dim1 = *ldu; + vt_offset = 1 + vt_dim1; + vt -= vt_offset; + u_dim1 = *ldu; + u_offset = 1 + u_dim1; + u -= u_offset; + --k; + --givptr; + perm_dim1 = *ldgcol; + perm_offset = 1 + perm_dim1; + perm -= perm_offset; + givcol_dim1 = *ldgcol; + givcol_offset = 1 + givcol_dim1; + givcol -= givcol_offset; + --c__; + --s; + --work; + --iwork; + + /* Function Body */ + *info = 0; + + if (*icompq < 0 || *icompq > 1) { + *info = -1; + } else if (*smlsiz < 3) { + *info = -2; + } else if (*n < 0) { + *info = -3; + } else if (*sqre < 0 || *sqre > 1) { + *info = -4; + } else if (*ldu < *n + *sqre) { + *info = -8; + } else if (*ldgcol < *n) { + *info = -17; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLASDA", &i__1); + return 0; + } + + m = *n + *sqre; + +/* If the input matrix is too small, call SLASDQ to find the SVD. */ + + if (*n <= *smlsiz) { + if (*icompq == 0) { + slasdq_("U", sqre, n, &c__0, &c__0, &c__0, &d__[1], &e[1], &vt[ + vt_offset], ldu, &u[u_offset], ldu, &u[u_offset], ldu, & + work[1], info); + } else { + slasdq_("U", sqre, n, &m, n, &c__0, &d__[1], &e[1], &vt[vt_offset] + , ldu, &u[u_offset], ldu, &u[u_offset], ldu, &work[1], + info); + } + return 0; + } + +/* Book-keeping and set up the computation tree. */ + + inode = 1; + ndiml = inode + *n; + ndimr = ndiml + *n; + idxq = ndimr + *n; + iwk = idxq + *n; + + ncc = 0; + nru = 0; + + smlszp = *smlsiz + 1; + vf = 1; + vl = vf + m; + nwork1 = vl + m; + nwork2 = nwork1 + smlszp * smlszp; + + slasdt_(n, &nlvl, &nd, &iwork[inode], &iwork[ndiml], &iwork[ndimr], + smlsiz); + +/* + for the nodes on bottom level of the tree, solve + their subproblems by SLASDQ. +*/ + + ndb1 = (nd + 1) / 2; + i__1 = nd; + for (i__ = ndb1; i__ <= i__1; ++i__) { + +/* + IC : center row of each node + NL : number of rows of left subproblem + NR : number of rows of right subproblem + NLF: starting row of the left subproblem + NRF: starting row of the right subproblem +*/ + + i1 = i__ - 1; + ic = iwork[inode + i1]; + nl = iwork[ndiml + i1]; + nlp1 = nl + 1; + nr = iwork[ndimr + i1]; + nlf = ic - nl; + nrf = ic + 1; + idxqi = idxq + nlf - 2; + vfi = vf + nlf - 1; + vli = vl + nlf - 1; + sqrei = 1; + if (*icompq == 0) { + slaset_("A", &nlp1, &nlp1, &c_b29, &c_b15, &work[nwork1], &smlszp); + slasdq_("U", &sqrei, &nl, &nlp1, &nru, &ncc, &d__[nlf], &e[nlf], & + work[nwork1], &smlszp, &work[nwork2], &nl, &work[nwork2], + &nl, &work[nwork2], info); + itemp = nwork1 + nl * smlszp; + scopy_(&nlp1, &work[nwork1], &c__1, &work[vfi], &c__1); + scopy_(&nlp1, &work[itemp], &c__1, &work[vli], &c__1); + } else { + slaset_("A", &nl, &nl, &c_b29, &c_b15, &u[nlf + u_dim1], ldu); + slaset_("A", &nlp1, &nlp1, &c_b29, &c_b15, &vt[nlf + vt_dim1], + ldu); + slasdq_("U", &sqrei, &nl, &nlp1, &nl, &ncc, &d__[nlf], &e[nlf], & + vt[nlf + vt_dim1], ldu, &u[nlf + u_dim1], ldu, &u[nlf + + u_dim1], ldu, &work[nwork1], info); + scopy_(&nlp1, &vt[nlf + vt_dim1], &c__1, &work[vfi], &c__1); + scopy_(&nlp1, &vt[nlf + nlp1 * vt_dim1], &c__1, &work[vli], &c__1) + ; + } + if (*info != 0) { + return 0; + } + i__2 = nl; + for (j = 1; j <= i__2; ++j) { + iwork[idxqi + j] = j; +/* L10: */ + } + if (i__ == nd && *sqre == 0) { + sqrei = 0; + } else { + sqrei = 1; + } + idxqi += nlp1; + vfi += nlp1; + vli += nlp1; + nrp1 = nr + sqrei; + if (*icompq == 0) { + slaset_("A", &nrp1, &nrp1, &c_b29, &c_b15, &work[nwork1], &smlszp); + slasdq_("U", &sqrei, &nr, &nrp1, &nru, &ncc, &d__[nrf], &e[nrf], & + work[nwork1], &smlszp, &work[nwork2], &nr, &work[nwork2], + &nr, &work[nwork2], info); + itemp = nwork1 + (nrp1 - 1) * smlszp; + scopy_(&nrp1, &work[nwork1], &c__1, &work[vfi], &c__1); + scopy_(&nrp1, &work[itemp], &c__1, &work[vli], &c__1); + } else { + slaset_("A", &nr, &nr, &c_b29, &c_b15, &u[nrf + u_dim1], ldu); + slaset_("A", &nrp1, &nrp1, &c_b29, &c_b15, &vt[nrf + vt_dim1], + ldu); + slasdq_("U", &sqrei, &nr, &nrp1, &nr, &ncc, &d__[nrf], &e[nrf], & + vt[nrf + vt_dim1], ldu, &u[nrf + u_dim1], ldu, &u[nrf + + u_dim1], ldu, &work[nwork1], info); + scopy_(&nrp1, &vt[nrf + vt_dim1], &c__1, &work[vfi], &c__1); + scopy_(&nrp1, &vt[nrf + nrp1 * vt_dim1], &c__1, &work[vli], &c__1) + ; + } + if (*info != 0) { + return 0; + } + i__2 = nr; + for (j = 1; j <= i__2; ++j) { + iwork[idxqi + j] = j; +/* L20: */ + } +/* L30: */ + } + +/* Now conquer each subproblem bottom-up. */ + + j = pow_ii(&c__2, &nlvl); + for (lvl = nlvl; lvl >= 1; --lvl) { + lvl2 = (lvl << 1) - 1; + +/* + Find the first node LF and last node LL on + the current level LVL. +*/ + + if (lvl == 1) { + lf = 1; + ll = 1; + } else { + i__1 = lvl - 1; + lf = pow_ii(&c__2, &i__1); + ll = (lf << 1) - 1; + } + i__1 = ll; + for (i__ = lf; i__ <= i__1; ++i__) { + im1 = i__ - 1; + ic = iwork[inode + im1]; + nl = iwork[ndiml + im1]; + nr = iwork[ndimr + im1]; + nlf = ic - nl; + nrf = ic + 1; + if (i__ == ll) { + sqrei = *sqre; + } else { + sqrei = 1; + } + vfi = vf + nlf - 1; + vli = vl + nlf - 1; + idxqi = idxq + nlf - 1; + alpha = d__[ic]; + beta = e[ic]; + if (*icompq == 0) { + slasd6_(icompq, &nl, &nr, &sqrei, &d__[nlf], &work[vfi], & + work[vli], &alpha, &beta, &iwork[idxqi], &perm[ + perm_offset], &givptr[1], &givcol[givcol_offset], + ldgcol, &givnum[givnum_offset], ldu, &poles[ + poles_offset], &difl[difl_offset], &difr[difr_offset], + &z__[z_offset], &k[1], &c__[1], &s[1], &work[nwork1], + &iwork[iwk], info); + } else { + --j; + slasd6_(icompq, &nl, &nr, &sqrei, &d__[nlf], &work[vfi], & + work[vli], &alpha, &beta, &iwork[idxqi], &perm[nlf + + lvl * perm_dim1], &givptr[j], &givcol[nlf + lvl2 * + givcol_dim1], ldgcol, &givnum[nlf + lvl2 * + givnum_dim1], ldu, &poles[nlf + lvl2 * poles_dim1], & + difl[nlf + lvl * difl_dim1], &difr[nlf + lvl2 * + difr_dim1], &z__[nlf + lvl * z_dim1], &k[j], &c__[j], + &s[j], &work[nwork1], &iwork[iwk], info); + } + if (*info != 0) { + return 0; + } +/* L40: */ + } +/* L50: */ + } + + return 0; + +/* End of SLASDA */ + +} /* slasda_ */ + +/* Subroutine */ int slasdq_(char *uplo, integer *sqre, integer *n, integer * + ncvt, integer *nru, integer *ncc, real *d__, real *e, real *vt, + integer *ldvt, real *u, integer *ldu, real *c__, integer *ldc, real * + work, integer *info) +{ + /* System generated locals */ + integer c_dim1, c_offset, u_dim1, u_offset, vt_dim1, vt_offset, i__1, + i__2; + + /* Local variables */ + static integer i__, j; + static real r__, cs, sn; + static integer np1, isub; + static real smin; + static integer sqre1; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int slasr_(char *, char *, char *, integer *, + integer *, real *, real *, real *, integer *); + static integer iuplo; + extern /* Subroutine */ int sswap_(integer *, real *, integer *, real *, + integer *), xerbla_(char *, integer *), slartg_(real *, + real *, real *, real *, real *); + static logical rotate; + extern /* Subroutine */ int sbdsqr_(char *, integer *, integer *, integer + *, integer *, real *, real *, real *, integer *, real *, integer * + , real *, integer *, real *, integer *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1999 + + + Purpose + ======= + + SLASDQ computes the singular value decomposition (SVD) of a real + (upper or lower) bidiagonal matrix with diagonal D and offdiagonal + E, accumulating the transformations if desired. Letting B denote + the input bidiagonal matrix, the algorithm computes orthogonal + matrices Q and P such that B = Q * S * P' (P' denotes the transpose + of P). The singular values S are overwritten on D. + + The input matrix U is changed to U * Q if desired. + The input matrix VT is changed to P' * VT if desired. + The input matrix C is changed to Q' * C if desired. + + See "Computing Small Singular Values of Bidiagonal Matrices With + Guaranteed High Relative Accuracy," by J. Demmel and W. Kahan, + LAPACK Working Note #3, for a detailed description of the algorithm. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + On entry, UPLO specifies whether the input bidiagonal matrix + is upper or lower bidiagonal, and wether it is square are + not. + UPLO = 'U' or 'u' B is upper bidiagonal. + UPLO = 'L' or 'l' B is lower bidiagonal. + + SQRE (input) INTEGER + = 0: then the input matrix is N-by-N. + = 1: then the input matrix is N-by-(N+1) if UPLU = 'U' and + (N+1)-by-N if UPLU = 'L'. + + The bidiagonal matrix has + N = NL + NR + 1 rows and + M = N + SQRE >= N columns. + + N (input) INTEGER + On entry, N specifies the number of rows and columns + in the matrix. N must be at least 0. + + NCVT (input) INTEGER + On entry, NCVT specifies the number of columns of + the matrix VT. NCVT must be at least 0. + + NRU (input) INTEGER + On entry, NRU specifies the number of rows of + the matrix U. NRU must be at least 0. + + NCC (input) INTEGER + On entry, NCC specifies the number of columns of + the matrix C. NCC must be at least 0. + + D (input/output) REAL array, dimension (N) + On entry, D contains the diagonal entries of the + bidiagonal matrix whose SVD is desired. On normal exit, + D contains the singular values in ascending order. + + E (input/output) REAL array. + dimension is (N-1) if SQRE = 0 and N if SQRE = 1. + On entry, the entries of E contain the offdiagonal entries + of the bidiagonal matrix whose SVD is desired. On normal + exit, E will contain 0. If the algorithm does not converge, + D and E will contain the diagonal and superdiagonal entries + of a bidiagonal matrix orthogonally equivalent to the one + given as input. + + VT (input/output) REAL array, dimension (LDVT, NCVT) + On entry, contains a matrix which on exit has been + premultiplied by P', dimension N-by-NCVT if SQRE = 0 + and (N+1)-by-NCVT if SQRE = 1 (not referenced if NCVT=0). + + LDVT (input) INTEGER + On entry, LDVT specifies the leading dimension of VT as + declared in the calling (sub) program. LDVT must be at + least 1. If NCVT is nonzero LDVT must also be at least N. + + U (input/output) REAL array, dimension (LDU, N) + On entry, contains a matrix which on exit has been + postmultiplied by Q, dimension NRU-by-N if SQRE = 0 + and NRU-by-(N+1) if SQRE = 1 (not referenced if NRU=0). + + LDU (input) INTEGER + On entry, LDU specifies the leading dimension of U as + declared in the calling (sub) program. LDU must be at + least max( 1, NRU ) . + + C (input/output) REAL array, dimension (LDC, NCC) + On entry, contains an N-by-NCC matrix which on exit + has been premultiplied by Q' dimension N-by-NCC if SQRE = 0 + and (N+1)-by-NCC if SQRE = 1 (not referenced if NCC=0). + + LDC (input) INTEGER + On entry, LDC specifies the leading dimension of C as + declared in the calling (sub) program. LDC must be at + least 1. If NCC is nonzero, LDC must also be at least N. + + WORK (workspace) REAL array, dimension (4*N) + Workspace. Only referenced if one of NCVT, NRU, or NCC is + nonzero, and if N is at least 2. + + INFO (output) INTEGER + On exit, a value of 0 indicates a successful exit. + If INFO < 0, argument number -INFO is illegal. + If INFO > 0, the algorithm did not converge, and INFO + specifies how many superdiagonals did not converge. + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --e; + vt_dim1 = *ldvt; + vt_offset = 1 + vt_dim1; + vt -= vt_offset; + u_dim1 = *ldu; + u_offset = 1 + u_dim1; + u -= u_offset; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + *info = 0; + iuplo = 0; + if (lsame_(uplo, "U")) { + iuplo = 1; + } + if (lsame_(uplo, "L")) { + iuplo = 2; + } + if (iuplo == 0) { + *info = -1; + } else if (*sqre < 0 || *sqre > 1) { + *info = -2; + } else if (*n < 0) { + *info = -3; + } else if (*ncvt < 0) { + *info = -4; + } else if (*nru < 0) { + *info = -5; + } else if (*ncc < 0) { + *info = -6; + } else if (*ncvt == 0 && *ldvt < 1 || *ncvt > 0 && *ldvt < max(1,*n)) { + *info = -10; + } else if (*ldu < max(1,*nru)) { + *info = -12; + } else if (*ncc == 0 && *ldc < 1 || *ncc > 0 && *ldc < max(1,*n)) { + *info = -14; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLASDQ", &i__1); + return 0; + } + if (*n == 0) { + return 0; + } + +/* ROTATE is true if any singular vectors desired, false otherwise */ + + rotate = *ncvt > 0 || *nru > 0 || *ncc > 0; + np1 = *n + 1; + sqre1 = *sqre; + +/* + If matrix non-square upper bidiagonal, rotate to be lower + bidiagonal. The rotations are on the right. +*/ + + if (iuplo == 1 && sqre1 == 1) { + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + slartg_(&d__[i__], &e[i__], &cs, &sn, &r__); + d__[i__] = r__; + e[i__] = sn * d__[i__ + 1]; + d__[i__ + 1] = cs * d__[i__ + 1]; + if (rotate) { + work[i__] = cs; + work[*n + i__] = sn; + } +/* L10: */ + } + slartg_(&d__[*n], &e[*n], &cs, &sn, &r__); + d__[*n] = r__; + e[*n] = 0.f; + if (rotate) { + work[*n] = cs; + work[*n + *n] = sn; + } + iuplo = 2; + sqre1 = 0; + +/* Update singular vectors if desired. */ + + if (*ncvt > 0) { + slasr_("L", "V", "F", &np1, ncvt, &work[1], &work[np1], &vt[ + vt_offset], ldvt); + } + } + +/* + If matrix lower bidiagonal, rotate to be upper bidiagonal + by applying Givens rotations on the left. +*/ + + if (iuplo == 2) { + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + slartg_(&d__[i__], &e[i__], &cs, &sn, &r__); + d__[i__] = r__; + e[i__] = sn * d__[i__ + 1]; + d__[i__ + 1] = cs * d__[i__ + 1]; + if (rotate) { + work[i__] = cs; + work[*n + i__] = sn; + } +/* L20: */ + } + +/* + If matrix (N+1)-by-N lower bidiagonal, one additional + rotation is needed. +*/ + + if (sqre1 == 1) { + slartg_(&d__[*n], &e[*n], &cs, &sn, &r__); + d__[*n] = r__; + if (rotate) { + work[*n] = cs; + work[*n + *n] = sn; + } + } + +/* Update singular vectors if desired. */ + + if (*nru > 0) { + if (sqre1 == 0) { + slasr_("R", "V", "F", nru, n, &work[1], &work[np1], &u[ + u_offset], ldu); + } else { + slasr_("R", "V", "F", nru, &np1, &work[1], &work[np1], &u[ + u_offset], ldu); + } + } + if (*ncc > 0) { + if (sqre1 == 0) { + slasr_("L", "V", "F", n, ncc, &work[1], &work[np1], &c__[ + c_offset], ldc); + } else { + slasr_("L", "V", "F", &np1, ncc, &work[1], &work[np1], &c__[ + c_offset], ldc); + } + } + } + +/* + Call SBDSQR to compute the SVD of the reduced real + N-by-N upper bidiagonal matrix. +*/ + + sbdsqr_("U", n, ncvt, nru, ncc, &d__[1], &e[1], &vt[vt_offset], ldvt, &u[ + u_offset], ldu, &c__[c_offset], ldc, &work[1], info); + +/* + Sort the singular values into ascending order (insertion sort on + singular values, but only one transposition per singular vector) +*/ + + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + +/* Scan for smallest D(I). */ + + isub = i__; + smin = d__[i__]; + i__2 = *n; + for (j = i__ + 1; j <= i__2; ++j) { + if (d__[j] < smin) { + isub = j; + smin = d__[j]; + } +/* L30: */ + } + if (isub != i__) { + +/* Swap singular values and vectors. */ + + d__[isub] = d__[i__]; + d__[i__] = smin; + if (*ncvt > 0) { + sswap_(ncvt, &vt[isub + vt_dim1], ldvt, &vt[i__ + vt_dim1], + ldvt); + } + if (*nru > 0) { + sswap_(nru, &u[isub * u_dim1 + 1], &c__1, &u[i__ * u_dim1 + 1] + , &c__1); + } + if (*ncc > 0) { + sswap_(ncc, &c__[isub + c_dim1], ldc, &c__[i__ + c_dim1], ldc) + ; + } + } +/* L40: */ + } + + return 0; + +/* End of SLASDQ */ + +} /* slasdq_ */ + +/* Subroutine */ int slasdt_(integer *n, integer *lvl, integer *nd, integer * + inode, integer *ndiml, integer *ndimr, integer *msub) +{ + /* System generated locals */ + integer i__1, i__2; + + /* Builtin functions */ + double log(doublereal); + + /* Local variables */ + static integer i__, il, ir, maxn; + static real temp; + static integer nlvl, llst, ncrnt; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1999 + + + Purpose + ======= + + SLASDT creates a tree of subproblems for bidiagonal divide and + conquer. + + Arguments + ========= + + N (input) INTEGER + On entry, the number of diagonal elements of the + bidiagonal matrix. + + LVL (output) INTEGER + On exit, the number of levels on the computation tree. + + ND (output) INTEGER + On exit, the number of nodes on the tree. + + INODE (output) INTEGER array, dimension ( N ) + On exit, centers of subproblems. + + NDIML (output) INTEGER array, dimension ( N ) + On exit, row dimensions of left children. + + NDIMR (output) INTEGER array, dimension ( N ) + On exit, row dimensions of right children. + + MSUB (input) INTEGER. + On entry, the maximum row dimension each subproblem at the + bottom of the tree can be of. + + Further Details + =============== + + Based on contributions by + Ming Gu and Huan Ren, Computer Science Division, University of + California at Berkeley, USA + + ===================================================================== + + + Find the number of levels on the tree. +*/ + + /* Parameter adjustments */ + --ndimr; + --ndiml; + --inode; + + /* Function Body */ + maxn = max(1,*n); + temp = log((real) maxn / (real) (*msub + 1)) / log(2.f); + *lvl = (integer) temp + 1; + + i__ = *n / 2; + inode[1] = i__ + 1; + ndiml[1] = i__; + ndimr[1] = *n - i__ - 1; + il = 0; + ir = 1; + llst = 1; + i__1 = *lvl - 1; + for (nlvl = 1; nlvl <= i__1; ++nlvl) { + +/* + Constructing the tree at (NLVL+1)-st level. The number of + nodes created on this level is LLST * 2. +*/ + + i__2 = llst - 1; + for (i__ = 0; i__ <= i__2; ++i__) { + il += 2; + ir += 2; + ncrnt = llst + i__; + ndiml[il] = ndiml[ncrnt] / 2; + ndimr[il] = ndiml[ncrnt] - ndiml[il] - 1; + inode[il] = inode[ncrnt] - ndimr[il] - 1; + ndiml[ir] = ndimr[ncrnt] / 2; + ndimr[ir] = ndimr[ncrnt] - ndiml[ir] - 1; + inode[ir] = inode[ncrnt] + ndiml[ir] + 1; +/* L10: */ + } + llst <<= 1; +/* L20: */ + } + *nd = (llst << 1) - 1; + + return 0; + +/* End of SLASDT */ + +} /* slasdt_ */ + +/* Subroutine */ int slaset_(char *uplo, integer *m, integer *n, real *alpha, + real *beta, real *a, integer *lda) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + + /* Local variables */ + static integer i__, j; + extern logical lsame_(char *, char *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLASET initializes an m-by-n matrix A to BETA on the diagonal and + ALPHA on the offdiagonals. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + Specifies the part of the matrix A to be set. + = 'U': Upper triangular part is set; the strictly lower + triangular part of A is not changed. + = 'L': Lower triangular part is set; the strictly upper + triangular part of A is not changed. + Otherwise: All of the matrix A is set. + + M (input) INTEGER + The number of rows of the matrix A. M >= 0. + + N (input) INTEGER + The number of columns of the matrix A. N >= 0. + + ALPHA (input) REAL + The constant to which the offdiagonal elements are to be set. + + BETA (input) REAL + The constant to which the diagonal elements are to be set. + + A (input/output) REAL array, dimension (LDA,N) + On exit, the leading m-by-n submatrix of A is set as follows: + + if UPLO = 'U', A(i,j) = ALPHA, 1<=i<=j-1, 1<=j<=n, + if UPLO = 'L', A(i,j) = ALPHA, j+1<=i<=m, 1<=j<=n, + otherwise, A(i,j) = ALPHA, 1<=i<=m, 1<=j<=n, i.ne.j, + + and, for all UPLO, A(i,i) = BETA, 1<=i<=min(m,n). + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + ===================================================================== +*/ + + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + + /* Function Body */ + if (lsame_(uplo, "U")) { + +/* + Set the strictly upper triangular or trapezoidal part of the + array to ALPHA. +*/ + + i__1 = *n; + for (j = 2; j <= i__1; ++j) { +/* Computing MIN */ + i__3 = j - 1; + i__2 = min(i__3,*m); + for (i__ = 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] = *alpha; +/* L10: */ + } +/* L20: */ + } + + } else if (lsame_(uplo, "L")) { + +/* + Set the strictly lower triangular or trapezoidal part of the + array to ALPHA. +*/ + + i__1 = min(*m,*n); + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = j + 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] = *alpha; +/* L30: */ + } +/* L40: */ + } + + } else { + +/* Set the leading m-by-n submatrix to ALPHA. */ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] = *alpha; +/* L50: */ + } +/* L60: */ + } + } + +/* Set the first min(M,N) diagonal elements to BETA. */ + + i__1 = min(*m,*n); + for (i__ = 1; i__ <= i__1; ++i__) { + a[i__ + i__ * a_dim1] = *beta; +/* L70: */ + } + + return 0; + +/* End of SLASET */ + +} /* slaset_ */ + +/* Subroutine */ int slasq1_(integer *n, real *d__, real *e, real *work, + integer *info) +{ + /* System generated locals */ + integer i__1, i__2; + real r__1, r__2, r__3; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static integer i__; + static real eps; + extern /* Subroutine */ int slas2_(real *, real *, real *, real *, real *) + ; + static real scale; + static integer iinfo; + static real sigmn, sigmx; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *), slasq2_(integer *, real *, integer *); + extern doublereal slamch_(char *); + static real safmin; + extern /* Subroutine */ int xerbla_(char *, integer *), slascl_( + char *, integer *, integer *, real *, real *, integer *, integer * + , real *, integer *, integer *), slasrt_(char *, integer * + , real *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1999 + + + Purpose + ======= + + SLASQ1 computes the singular values of a real N-by-N bidiagonal + matrix with diagonal D and off-diagonal E. The singular values + are computed to high relative accuracy, in the absence of + denormalization, underflow and overflow. The algorithm was first + presented in + + "Accurate singular values and differential qd algorithms" by K. V. + Fernando and B. N. Parlett, Numer. Math., Vol-67, No. 2, pp. 191-230, + 1994, + + and the present implementation is described in "An implementation of + the dqds Algorithm (Positive Case)", LAPACK Working Note. + + Arguments + ========= + + N (input) INTEGER + The number of rows and columns in the matrix. N >= 0. + + D (input/output) REAL array, dimension (N) + On entry, D contains the diagonal elements of the + bidiagonal matrix whose SVD is desired. On normal exit, + D contains the singular values in decreasing order. + + E (input/output) REAL array, dimension (N) + On entry, elements E(1:N-1) contain the off-diagonal elements + of the bidiagonal matrix whose SVD is desired. + On exit, E is overwritten. + + WORK (workspace) REAL array, dimension (4*N) + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + > 0: the algorithm failed + = 1, a split was marked by a positive value in E + = 2, current block of Z not diagonalized after 30*N + iterations (in inner while loop) + = 3, termination criterion of outer while loop not met + (program created more than N unreduced blocks) + + ===================================================================== +*/ + + + /* Parameter adjustments */ + --work; + --e; + --d__; + + /* Function Body */ + *info = 0; + if (*n < 0) { + *info = -2; + i__1 = -(*info); + xerbla_("SLASQ1", &i__1); + return 0; + } else if (*n == 0) { + return 0; + } else if (*n == 1) { + d__[1] = dabs(d__[1]); + return 0; + } else if (*n == 2) { + slas2_(&d__[1], &e[1], &d__[2], &sigmn, &sigmx); + d__[1] = sigmx; + d__[2] = sigmn; + return 0; + } + +/* Estimate the largest singular value. */ + + sigmx = 0.f; + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + d__[i__] = (r__1 = d__[i__], dabs(r__1)); +/* Computing MAX */ + r__2 = sigmx, r__3 = (r__1 = e[i__], dabs(r__1)); + sigmx = dmax(r__2,r__3); +/* L10: */ + } + d__[*n] = (r__1 = d__[*n], dabs(r__1)); + +/* Early return if SIGMX is zero (matrix is already diagonal). */ + + if (sigmx == 0.f) { + slasrt_("D", n, &d__[1], &iinfo); + return 0; + } + + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { +/* Computing MAX */ + r__1 = sigmx, r__2 = d__[i__]; + sigmx = dmax(r__1,r__2); +/* L20: */ + } + +/* + Copy D and E into WORK (in the Z format) and scale (squaring the + input data makes scaling by a power of the radix pointless). +*/ + + eps = slamch_("Precision"); + safmin = slamch_("Safe minimum"); + scale = sqrt(eps / safmin); + scopy_(n, &d__[1], &c__1, &work[1], &c__2); + i__1 = *n - 1; + scopy_(&i__1, &e[1], &c__1, &work[2], &c__2); + i__1 = (*n << 1) - 1; + i__2 = (*n << 1) - 1; + slascl_("G", &c__0, &c__0, &sigmx, &scale, &i__1, &c__1, &work[1], &i__2, + &iinfo); + +/* Compute the q's and e's. */ + + i__1 = (*n << 1) - 1; + for (i__ = 1; i__ <= i__1; ++i__) { +/* Computing 2nd power */ + r__1 = work[i__]; + work[i__] = r__1 * r__1; +/* L30: */ + } + work[*n * 2] = 0.f; + + slasq2_(n, &work[1], info); + + if (*info == 0) { + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + d__[i__] = sqrt(work[i__]); +/* L40: */ + } + slascl_("G", &c__0, &c__0, &scale, &sigmx, n, &c__1, &d__[1], n, & + iinfo); + } + + return 0; + +/* End of SLASQ1 */ + +} /* slasq1_ */ + +/* Subroutine */ int slasq2_(integer *n, real *z__, integer *info) +{ + /* System generated locals */ + integer i__1, i__2, i__3; + real r__1, r__2; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real d__, e; + static integer k; + static real s, t; + static integer i0, i4, n0, pp; + static real eps, tol; + static integer ipn4; + static real tol2; + static logical ieee; + static integer nbig; + static real dmin__, emin, emax; + static integer ndiv, iter; + static real qmin, temp, qmax, zmax; + static integer splt, nfail; + static real desig, trace, sigma; + static integer iinfo; + extern /* Subroutine */ int slasq3_(integer *, integer *, real *, integer + *, real *, real *, real *, real *, integer *, integer *, integer * + , logical *); + extern doublereal slamch_(char *); + static integer iwhila, iwhilb; + static real oldemn, safmin; + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slasrt_(char *, integer *, real *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1999 + + + Purpose + ======= + + SLASQ2 computes all the eigenvalues of the symmetric positive + definite tridiagonal matrix associated with the qd array Z to high + relative accuracy are computed to high relative accuracy, in the + absence of denormalization, underflow and overflow. + + To see the relation of Z to the tridiagonal matrix, let L be a + unit lower bidiagonal matrix with subdiagonals Z(2,4,6,,..) and + let U be an upper bidiagonal matrix with 1's above and diagonal + Z(1,3,5,,..). The tridiagonal is L*U or, if you prefer, the + symmetric tridiagonal to which it is similar. + + Note : SLASQ2 defines a logical variable, IEEE, which is true + on machines which follow ieee-754 floating-point standard in their + handling of infinities and NaNs, and false otherwise. This variable + is passed to SLASQ3. + + Arguments + ========= + + N (input) INTEGER + The number of rows and columns in the matrix. N >= 0. + + Z (workspace) REAL array, dimension ( 4*N ) + On entry Z holds the qd array. On exit, entries 1 to N hold + the eigenvalues in decreasing order, Z( 2*N+1 ) holds the + trace, and Z( 2*N+2 ) holds the sum of the eigenvalues. If + N > 2, then Z( 2*N+3 ) holds the iteration count, Z( 2*N+4 ) + holds NDIVS/NIN^2, and Z( 2*N+5 ) holds the percentage of + shifts that failed. + + INFO (output) INTEGER + = 0: successful exit + < 0: if the i-th argument is a scalar and had an illegal + value, then INFO = -i, if the i-th argument is an + array and the j-entry had an illegal value, then + INFO = -(i*100+j) + > 0: the algorithm failed + = 1, a split was marked by a positive value in E + = 2, current block of Z not diagonalized after 30*N + iterations (in inner while loop) + = 3, termination criterion of outer while loop not met + (program created more than N unreduced blocks) + + Further Details + =============== + Local Variables: I0:N0 defines a current unreduced segment of Z. + The shifts are accumulated in SIGMA. Iteration count is in ITER. + Ping-pong is controlled by PP (alternates between 0 and 1). + + ===================================================================== + + + Test the input arguments. + (in case SLASQ2 is not called by SLASQ1) +*/ + + /* Parameter adjustments */ + --z__; + + /* Function Body */ + *info = 0; + eps = slamch_("Precision"); + safmin = slamch_("Safe minimum"); + tol = eps * 100.f; +/* Computing 2nd power */ + r__1 = tol; + tol2 = r__1 * r__1; + + if (*n < 0) { + *info = -1; + xerbla_("SLASQ2", &c__1); + return 0; + } else if (*n == 0) { + return 0; + } else if (*n == 1) { + +/* 1-by-1 case. */ + + if (z__[1] < 0.f) { + *info = -201; + xerbla_("SLASQ2", &c__2); + } + return 0; + } else if (*n == 2) { + +/* 2-by-2 case. */ + + if (z__[2] < 0.f || z__[3] < 0.f) { + *info = -2; + xerbla_("SLASQ2", &c__2); + return 0; + } else if (z__[3] > z__[1]) { + d__ = z__[3]; + z__[3] = z__[1]; + z__[1] = d__; + } + z__[5] = z__[1] + z__[2] + z__[3]; + if (z__[2] > z__[3] * tol2) { + t = (z__[1] - z__[3] + z__[2]) * .5f; + s = z__[3] * (z__[2] / t); + if (s <= t) { + s = z__[3] * (z__[2] / (t * (sqrt(s / t + 1.f) + 1.f))); + } else { + s = z__[3] * (z__[2] / (t + sqrt(t) * sqrt(t + s))); + } + t = z__[1] + (s + z__[2]); + z__[3] *= z__[1] / t; + z__[1] = t; + } + z__[2] = z__[3]; + z__[6] = z__[2] + z__[1]; + return 0; + } + +/* Check for negative data and compute sums of q's and e's. */ + + z__[*n * 2] = 0.f; + emin = z__[2]; + qmax = 0.f; + zmax = 0.f; + d__ = 0.f; + e = 0.f; + + i__1 = *n - 1 << 1; + for (k = 1; k <= i__1; k += 2) { + if (z__[k] < 0.f) { + *info = -(k + 200); + xerbla_("SLASQ2", &c__2); + return 0; + } else if (z__[k + 1] < 0.f) { + *info = -(k + 201); + xerbla_("SLASQ2", &c__2); + return 0; + } + d__ += z__[k]; + e += z__[k + 1]; +/* Computing MAX */ + r__1 = qmax, r__2 = z__[k]; + qmax = dmax(r__1,r__2); +/* Computing MIN */ + r__1 = emin, r__2 = z__[k + 1]; + emin = dmin(r__1,r__2); +/* Computing MAX */ + r__1 = max(qmax,zmax), r__2 = z__[k + 1]; + zmax = dmax(r__1,r__2); +/* L10: */ + } + if (z__[(*n << 1) - 1] < 0.f) { + *info = -((*n << 1) + 199); + xerbla_("SLASQ2", &c__2); + return 0; + } + d__ += z__[(*n << 1) - 1]; +/* Computing MAX */ + r__1 = qmax, r__2 = z__[(*n << 1) - 1]; + qmax = dmax(r__1,r__2); + zmax = dmax(qmax,zmax); + +/* Check for diagonality. */ + + if (e == 0.f) { + i__1 = *n; + for (k = 2; k <= i__1; ++k) { + z__[k] = z__[(k << 1) - 1]; +/* L20: */ + } + slasrt_("D", n, &z__[1], &iinfo); + z__[(*n << 1) - 1] = d__; + return 0; + } + + trace = d__ + e; + +/* Check for zero data. */ + + if (trace == 0.f) { + z__[(*n << 1) - 1] = 0.f; + return 0; + } + +/* Check whether the machine is IEEE conformable. */ + + ieee = ilaenv_(&c__10, "SLASQ2", "N", &c__1, &c__2, &c__3, &c__4, (ftnlen) + 6, (ftnlen)1) == 1 && ilaenv_(&c__11, "SLASQ2", "N", &c__1, &c__2, + &c__3, &c__4, (ftnlen)6, (ftnlen)1) == 1; + +/* Rearrange data for locality: Z=(q1,qq1,e1,ee1,q2,qq2,e2,ee2,...). */ + + for (k = *n << 1; k >= 2; k += -2) { + z__[k * 2] = 0.f; + z__[(k << 1) - 1] = z__[k]; + z__[(k << 1) - 2] = 0.f; + z__[(k << 1) - 3] = z__[k - 1]; +/* L30: */ + } + + i0 = 1; + n0 = *n; + +/* Reverse the qd-array, if warranted. */ + + if (z__[(i0 << 2) - 3] * 1.5f < z__[(n0 << 2) - 3]) { + ipn4 = i0 + n0 << 2; + i__1 = i0 + n0 - 1 << 1; + for (i4 = i0 << 2; i4 <= i__1; i4 += 4) { + temp = z__[i4 - 3]; + z__[i4 - 3] = z__[ipn4 - i4 - 3]; + z__[ipn4 - i4 - 3] = temp; + temp = z__[i4 - 1]; + z__[i4 - 1] = z__[ipn4 - i4 - 5]; + z__[ipn4 - i4 - 5] = temp; +/* L40: */ + } + } + +/* Initial split checking via dqd and Li's test. */ + + pp = 0; + + for (k = 1; k <= 2; ++k) { + + d__ = z__[(n0 << 2) + pp - 3]; + i__1 = (i0 << 2) + pp; + for (i4 = (n0 - 1 << 2) + pp; i4 >= i__1; i4 += -4) { + if (z__[i4 - 1] <= tol2 * d__) { + z__[i4 - 1] = -0.f; + d__ = z__[i4 - 3]; + } else { + d__ = z__[i4 - 3] * (d__ / (d__ + z__[i4 - 1])); + } +/* L50: */ + } + +/* dqd maps Z to ZZ plus Li's test. */ + + emin = z__[(i0 << 2) + pp + 1]; + d__ = z__[(i0 << 2) + pp - 3]; + i__1 = (n0 - 1 << 2) + pp; + for (i4 = (i0 << 2) + pp; i4 <= i__1; i4 += 4) { + z__[i4 - (pp << 1) - 2] = d__ + z__[i4 - 1]; + if (z__[i4 - 1] <= tol2 * d__) { + z__[i4 - 1] = -0.f; + z__[i4 - (pp << 1) - 2] = d__; + z__[i4 - (pp << 1)] = 0.f; + d__ = z__[i4 + 1]; + } else if (safmin * z__[i4 + 1] < z__[i4 - (pp << 1) - 2] && + safmin * z__[i4 - (pp << 1) - 2] < z__[i4 + 1]) { + temp = z__[i4 + 1] / z__[i4 - (pp << 1) - 2]; + z__[i4 - (pp << 1)] = z__[i4 - 1] * temp; + d__ *= temp; + } else { + z__[i4 - (pp << 1)] = z__[i4 + 1] * (z__[i4 - 1] / z__[i4 - ( + pp << 1) - 2]); + d__ = z__[i4 + 1] * (d__ / z__[i4 - (pp << 1) - 2]); + } +/* Computing MIN */ + r__1 = emin, r__2 = z__[i4 - (pp << 1)]; + emin = dmin(r__1,r__2); +/* L60: */ + } + z__[(n0 << 2) - pp - 2] = d__; + +/* Now find qmax. */ + + qmax = z__[(i0 << 2) - pp - 2]; + i__1 = (n0 << 2) - pp - 2; + for (i4 = (i0 << 2) - pp + 2; i4 <= i__1; i4 += 4) { +/* Computing MAX */ + r__1 = qmax, r__2 = z__[i4]; + qmax = dmax(r__1,r__2); +/* L70: */ + } + +/* Prepare for the next iteration on K. */ + + pp = 1 - pp; +/* L80: */ + } + + iter = 2; + nfail = 0; + ndiv = n0 - i0 << 1; + + i__1 = *n + 1; + for (iwhila = 1; iwhila <= i__1; ++iwhila) { + if (n0 < 1) { + goto L150; + } + +/* + While array unfinished do + + E(N0) holds the value of SIGMA when submatrix in I0:N0 + splits from the rest of the array, but is negated. +*/ + + desig = 0.f; + if (n0 == *n) { + sigma = 0.f; + } else { + sigma = -z__[(n0 << 2) - 1]; + } + if (sigma < 0.f) { + *info = 1; + return 0; + } + +/* + Find last unreduced submatrix's top index I0, find QMAX and + EMIN. Find Gershgorin-type bound if Q's much greater than E's. +*/ + + emax = 0.f; + if (n0 > i0) { + emin = (r__1 = z__[(n0 << 2) - 5], dabs(r__1)); + } else { + emin = 0.f; + } + qmin = z__[(n0 << 2) - 3]; + qmax = qmin; + for (i4 = n0 << 2; i4 >= 8; i4 += -4) { + if (z__[i4 - 5] <= 0.f) { + goto L100; + } + if (qmin >= emax * 4.f) { +/* Computing MIN */ + r__1 = qmin, r__2 = z__[i4 - 3]; + qmin = dmin(r__1,r__2); +/* Computing MAX */ + r__1 = emax, r__2 = z__[i4 - 5]; + emax = dmax(r__1,r__2); + } +/* Computing MAX */ + r__1 = qmax, r__2 = z__[i4 - 7] + z__[i4 - 5]; + qmax = dmax(r__1,r__2); +/* Computing MIN */ + r__1 = emin, r__2 = z__[i4 - 5]; + emin = dmin(r__1,r__2); +/* L90: */ + } + i4 = 4; + +L100: + i0 = i4 / 4; + +/* Store EMIN for passing to SLASQ3. */ + + z__[(n0 << 2) - 1] = emin; + +/* + Put -(initial shift) into DMIN. + + Computing MAX +*/ + r__1 = 0.f, r__2 = qmin - sqrt(qmin) * 2.f * sqrt(emax); + dmin__ = -dmax(r__1,r__2); + +/* Now I0:N0 is unreduced. PP = 0 for ping, PP = 1 for pong. */ + + pp = 0; + + nbig = (n0 - i0 + 1) * 30; + i__2 = nbig; + for (iwhilb = 1; iwhilb <= i__2; ++iwhilb) { + if (i0 > n0) { + goto L130; + } + +/* While submatrix unfinished take a good dqds step. */ + + slasq3_(&i0, &n0, &z__[1], &pp, &dmin__, &sigma, &desig, &qmax, & + nfail, &iter, &ndiv, &ieee); + + pp = 1 - pp; + +/* When EMIN is very small check for splits. */ + + if (pp == 0 && n0 - i0 >= 3) { + if (z__[n0 * 4] <= tol2 * qmax || z__[(n0 << 2) - 1] <= tol2 * + sigma) { + splt = i0 - 1; + qmax = z__[(i0 << 2) - 3]; + emin = z__[(i0 << 2) - 1]; + oldemn = z__[i0 * 4]; + i__3 = n0 - 3 << 2; + for (i4 = i0 << 2; i4 <= i__3; i4 += 4) { + if (z__[i4] <= tol2 * z__[i4 - 3] || z__[i4 - 1] <= + tol2 * sigma) { + z__[i4 - 1] = -sigma; + splt = i4 / 4; + qmax = 0.f; + emin = z__[i4 + 3]; + oldemn = z__[i4 + 4]; + } else { +/* Computing MAX */ + r__1 = qmax, r__2 = z__[i4 + 1]; + qmax = dmax(r__1,r__2); +/* Computing MIN */ + r__1 = emin, r__2 = z__[i4 - 1]; + emin = dmin(r__1,r__2); +/* Computing MIN */ + r__1 = oldemn, r__2 = z__[i4]; + oldemn = dmin(r__1,r__2); + } +/* L110: */ + } + z__[(n0 << 2) - 1] = emin; + z__[n0 * 4] = oldemn; + i0 = splt + 1; + } + } + +/* L120: */ + } + + *info = 2; + return 0; + +/* end IWHILB */ + +L130: + +/* L140: */ + ; + } + + *info = 3; + return 0; + +/* end IWHILA */ + +L150: + +/* Move q's to the front. */ + + i__1 = *n; + for (k = 2; k <= i__1; ++k) { + z__[k] = z__[(k << 2) - 3]; +/* L160: */ + } + +/* Sort and compute sum of eigenvalues. */ + + slasrt_("D", n, &z__[1], &iinfo); + + e = 0.f; + for (k = *n; k >= 1; --k) { + e += z__[k]; +/* L170: */ + } + +/* Store trace, sum(eigenvalues) and information on performance. */ + + z__[(*n << 1) + 1] = trace; + z__[(*n << 1) + 2] = e; + z__[(*n << 1) + 3] = (real) iter; +/* Computing 2nd power */ + i__1 = *n; + z__[(*n << 1) + 4] = (real) ndiv / (real) (i__1 * i__1); + z__[(*n << 1) + 5] = nfail * 100.f / (real) iter; + return 0; + +/* End of SLASQ2 */ + +} /* slasq2_ */ + +/* Subroutine */ int slasq3_(integer *i0, integer *n0, real *z__, integer *pp, + real *dmin__, real *sigma, real *desig, real *qmax, integer *nfail, + integer *iter, integer *ndiv, logical *ieee) +{ + /* Initialized data */ + + static integer ttype = 0; + static real dmin1 = 0.f; + static real dmin2 = 0.f; + static real dn = 0.f; + static real dn1 = 0.f; + static real dn2 = 0.f; + static real tau = 0.f; + + /* System generated locals */ + integer i__1; + real r__1, r__2; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real s, t; + static integer j4, nn; + static real eps, tol; + static integer n0in, ipn4; + static real tol2, temp; + extern /* Subroutine */ int slasq4_(integer *, integer *, real *, integer + *, integer *, real *, real *, real *, real *, real *, real *, + real *, integer *), slasq5_(integer *, integer *, real *, integer + *, real *, real *, real *, real *, real *, real *, real *, + logical *), slasq6_(integer *, integer *, real *, integer *, real + *, real *, real *, real *, real *, real *); + extern doublereal slamch_(char *); + static real safmin; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + May 17, 2000 + + + Purpose + ======= + + SLASQ3 checks for deflation, computes a shift (TAU) and calls dqds. + In case of failure it changes shifts, and tries again until output + is positive. + + Arguments + ========= + + I0 (input) INTEGER + First index. + + N0 (input) INTEGER + Last index. + + Z (input) REAL array, dimension ( 4*N ) + Z holds the qd array. + + PP (input) INTEGER + PP=0 for ping, PP=1 for pong. + + DMIN (output) REAL + Minimum value of d. + + SIGMA (output) REAL + Sum of shifts used in current segment. + + DESIG (input/output) REAL + Lower order part of SIGMA + + QMAX (input) REAL + Maximum value of q. + + NFAIL (output) INTEGER + Number of times shift was too big. + + ITER (output) INTEGER + Number of iterations. + + NDIV (output) INTEGER + Number of divisions. + + TTYPE (output) INTEGER + Shift type. + + IEEE (input) LOGICAL + Flag for IEEE or non IEEE arithmetic (passed to SLASQ5). + + ===================================================================== +*/ + + /* Parameter adjustments */ + --z__; + + /* Function Body */ + + n0in = *n0; + eps = slamch_("Precision"); + safmin = slamch_("Safe minimum"); + tol = eps * 100.f; +/* Computing 2nd power */ + r__1 = tol; + tol2 = r__1 * r__1; + +/* Check for deflation. */ + +L10: + + if (*n0 < *i0) { + return 0; + } + if (*n0 == *i0) { + goto L20; + } + nn = (*n0 << 2) + *pp; + if (*n0 == *i0 + 1) { + goto L40; + } + +/* Check whether E(N0-1) is negligible, 1 eigenvalue. */ + + if (z__[nn - 5] > tol2 * (*sigma + z__[nn - 3]) && z__[nn - (*pp << 1) - + 4] > tol2 * z__[nn - 7]) { + goto L30; + } + +L20: + + z__[(*n0 << 2) - 3] = z__[(*n0 << 2) + *pp - 3] + *sigma; + --(*n0); + goto L10; + +/* Check whether E(N0-2) is negligible, 2 eigenvalues. */ + +L30: + + if (z__[nn - 9] > tol2 * *sigma && z__[nn - (*pp << 1) - 8] > tol2 * z__[ + nn - 11]) { + goto L50; + } + +L40: + + if (z__[nn - 3] > z__[nn - 7]) { + s = z__[nn - 3]; + z__[nn - 3] = z__[nn - 7]; + z__[nn - 7] = s; + } + if (z__[nn - 5] > z__[nn - 3] * tol2) { + t = (z__[nn - 7] - z__[nn - 3] + z__[nn - 5]) * .5f; + s = z__[nn - 3] * (z__[nn - 5] / t); + if (s <= t) { + s = z__[nn - 3] * (z__[nn - 5] / (t * (sqrt(s / t + 1.f) + 1.f))); + } else { + s = z__[nn - 3] * (z__[nn - 5] / (t + sqrt(t) * sqrt(t + s))); + } + t = z__[nn - 7] + (s + z__[nn - 5]); + z__[nn - 3] *= z__[nn - 7] / t; + z__[nn - 7] = t; + } + z__[(*n0 << 2) - 7] = z__[nn - 7] + *sigma; + z__[(*n0 << 2) - 3] = z__[nn - 3] + *sigma; + *n0 += -2; + goto L10; + +L50: + +/* Reverse the qd-array, if warranted. */ + + if (*dmin__ <= 0.f || *n0 < n0in) { + if (z__[(*i0 << 2) + *pp - 3] * 1.5f < z__[(*n0 << 2) + *pp - 3]) { + ipn4 = *i0 + *n0 << 2; + i__1 = *i0 + *n0 - 1 << 1; + for (j4 = *i0 << 2; j4 <= i__1; j4 += 4) { + temp = z__[j4 - 3]; + z__[j4 - 3] = z__[ipn4 - j4 - 3]; + z__[ipn4 - j4 - 3] = temp; + temp = z__[j4 - 2]; + z__[j4 - 2] = z__[ipn4 - j4 - 2]; + z__[ipn4 - j4 - 2] = temp; + temp = z__[j4 - 1]; + z__[j4 - 1] = z__[ipn4 - j4 - 5]; + z__[ipn4 - j4 - 5] = temp; + temp = z__[j4]; + z__[j4] = z__[ipn4 - j4 - 4]; + z__[ipn4 - j4 - 4] = temp; +/* L60: */ + } + if (*n0 - *i0 <= 4) { + z__[(*n0 << 2) + *pp - 1] = z__[(*i0 << 2) + *pp - 1]; + z__[(*n0 << 2) - *pp] = z__[(*i0 << 2) - *pp]; + } +/* Computing MIN */ + r__1 = dmin2, r__2 = z__[(*n0 << 2) + *pp - 1]; + dmin2 = dmin(r__1,r__2); +/* Computing MIN */ + r__1 = z__[(*n0 << 2) + *pp - 1], r__2 = z__[(*i0 << 2) + *pp - 1] + , r__1 = min(r__1,r__2), r__2 = z__[(*i0 << 2) + *pp + 3]; + z__[(*n0 << 2) + *pp - 1] = dmin(r__1,r__2); +/* Computing MIN */ + r__1 = z__[(*n0 << 2) - *pp], r__2 = z__[(*i0 << 2) - *pp], r__1 = + min(r__1,r__2), r__2 = z__[(*i0 << 2) - *pp + 4]; + z__[(*n0 << 2) - *pp] = dmin(r__1,r__2); +/* Computing MAX */ + r__1 = *qmax, r__2 = z__[(*i0 << 2) + *pp - 3], r__1 = max(r__1, + r__2), r__2 = z__[(*i0 << 2) + *pp + 1]; + *qmax = dmax(r__1,r__2); + *dmin__ = -0.f; + } + } + +/* + L70: + + Computing MIN +*/ + r__1 = z__[(*n0 << 2) + *pp - 1], r__2 = z__[(*n0 << 2) + *pp - 9], r__1 = + min(r__1,r__2), r__2 = dmin2 + z__[(*n0 << 2) - *pp]; + if (*dmin__ < 0.f || safmin * *qmax < dmin(r__1,r__2)) { + +/* Choose a shift. */ + + slasq4_(i0, n0, &z__[1], pp, &n0in, dmin__, &dmin1, &dmin2, &dn, &dn1, + &dn2, &tau, &ttype); + +/* Call dqds until DMIN > 0. */ + +L80: + + slasq5_(i0, n0, &z__[1], pp, &tau, dmin__, &dmin1, &dmin2, &dn, &dn1, + &dn2, ieee); + + *ndiv += *n0 - *i0 + 2; + ++(*iter); + +/* Check status. */ + + if (*dmin__ >= 0.f && dmin1 > 0.f) { + +/* Success. */ + + goto L100; + + } else if (*dmin__ < 0.f && dmin1 > 0.f && z__[(*n0 - 1 << 2) - *pp] < + tol * (*sigma + dn1) && dabs(dn) < tol * *sigma) { + +/* Convergence hidden by negative DN. */ + + z__[(*n0 - 1 << 2) - *pp + 2] = 0.f; + *dmin__ = 0.f; + goto L100; + } else if (*dmin__ < 0.f) { + +/* TAU too big. Select new TAU and try again. */ + + ++(*nfail); + if (ttype < -22) { + +/* Failed twice. Play it safe. */ + + tau = 0.f; + } else if (dmin1 > 0.f) { + +/* Late failure. Gives excellent shift. */ + + tau = (tau + *dmin__) * (1.f - eps * 2.f); + ttype += -11; + } else { + +/* Early failure. Divide by 4. */ + + tau *= .25f; + ttype += -12; + } + goto L80; + } else if (*dmin__ != *dmin__) { + +/* NaN. */ + + tau = 0.f; + goto L80; + } else { + +/* Possible underflow. Play it safe. */ + + goto L90; + } + } + +/* Risk of underflow. */ + +L90: + slasq6_(i0, n0, &z__[1], pp, dmin__, &dmin1, &dmin2, &dn, &dn1, &dn2); + *ndiv += *n0 - *i0 + 2; + ++(*iter); + tau = 0.f; + +L100: + if (tau < *sigma) { + *desig += tau; + t = *sigma + *desig; + *desig -= t - *sigma; + } else { + t = *sigma + tau; + *desig = *sigma - (t - tau) + *desig; + } + *sigma = t; + + return 0; + +/* End of SLASQ3 */ + +} /* slasq3_ */ + +/* Subroutine */ int slasq4_(integer *i0, integer *n0, real *z__, integer *pp, + integer *n0in, real *dmin__, real *dmin1, real *dmin2, real *dn, + real *dn1, real *dn2, real *tau, integer *ttype) +{ + /* Initialized data */ + + static real g = 0.f; + + /* System generated locals */ + integer i__1; + real r__1, r__2; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real s, a2, b1, b2; + static integer i4, nn, np; + static real gam, gap1, gap2; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1999 + + + Purpose + ======= + + SLASQ4 computes an approximation TAU to the smallest eigenvalue + using values of d from the previous transform. + + I0 (input) INTEGER + First index. + + N0 (input) INTEGER + Last index. + + Z (input) REAL array, dimension ( 4*N ) + Z holds the qd array. + + PP (input) INTEGER + PP=0 for ping, PP=1 for pong. + + NOIN (input) INTEGER + The value of N0 at start of EIGTEST. + + DMIN (input) REAL + Minimum value of d. + + DMIN1 (input) REAL + Minimum value of d, excluding D( N0 ). + + DMIN2 (input) REAL + Minimum value of d, excluding D( N0 ) and D( N0-1 ). + + DN (input) REAL + d(N) + + DN1 (input) REAL + d(N-1) + + DN2 (input) REAL + d(N-2) + + TAU (output) REAL + This is the shift. + + TTYPE (output) INTEGER + Shift type. + + Further Details + =============== + CNST1 = 9/16 + + ===================================================================== +*/ + + /* Parameter adjustments */ + --z__; + + /* Function Body */ + +/* + A negative DMIN forces the shift to take that absolute value + TTYPE records the type of shift. +*/ + + if (*dmin__ <= 0.f) { + *tau = -(*dmin__); + *ttype = -1; + return 0; + } + + nn = (*n0 << 2) + *pp; + if (*n0in == *n0) { + +/* No eigenvalues deflated. */ + + if (*dmin__ == *dn || *dmin__ == *dn1) { + + b1 = sqrt(z__[nn - 3]) * sqrt(z__[nn - 5]); + b2 = sqrt(z__[nn - 7]) * sqrt(z__[nn - 9]); + a2 = z__[nn - 7] + z__[nn - 5]; + +/* Cases 2 and 3. */ + + if (*dmin__ == *dn && *dmin1 == *dn1) { + gap2 = *dmin2 - a2 - *dmin2 * .25f; + if (gap2 > 0.f && gap2 > b2) { + gap1 = a2 - *dn - b2 / gap2 * b2; + } else { + gap1 = a2 - *dn - (b1 + b2); + } + if (gap1 > 0.f && gap1 > b1) { +/* Computing MAX */ + r__1 = *dn - b1 / gap1 * b1, r__2 = *dmin__ * .5f; + s = dmax(r__1,r__2); + *ttype = -2; + } else { + s = 0.f; + if (*dn > b1) { + s = *dn - b1; + } + if (a2 > b1 + b2) { +/* Computing MIN */ + r__1 = s, r__2 = a2 - (b1 + b2); + s = dmin(r__1,r__2); + } +/* Computing MAX */ + r__1 = s, r__2 = *dmin__ * .333f; + s = dmax(r__1,r__2); + *ttype = -3; + } + } else { + +/* Case 4. */ + + *ttype = -4; + s = *dmin__ * .25f; + if (*dmin__ == *dn) { + gam = *dn; + a2 = 0.f; + if (z__[nn - 5] > z__[nn - 7]) { + return 0; + } + b2 = z__[nn - 5] / z__[nn - 7]; + np = nn - 9; + } else { + np = nn - (*pp << 1); + b2 = z__[np - 2]; + gam = *dn1; + if (z__[np - 4] > z__[np - 2]) { + return 0; + } + a2 = z__[np - 4] / z__[np - 2]; + if (z__[nn - 9] > z__[nn - 11]) { + return 0; + } + b2 = z__[nn - 9] / z__[nn - 11]; + np = nn - 13; + } + +/* Approximate contribution to norm squared from I < NN-1. */ + + a2 += b2; + i__1 = (*i0 << 2) - 1 + *pp; + for (i4 = np; i4 >= i__1; i4 += -4) { + if (b2 == 0.f) { + goto L20; + } + b1 = b2; + if (z__[i4] > z__[i4 - 2]) { + return 0; + } + b2 *= z__[i4] / z__[i4 - 2]; + a2 += b2; + if (dmax(b2,b1) * 100.f < a2 || .563f < a2) { + goto L20; + } +/* L10: */ + } +L20: + a2 *= 1.05f; + +/* Rayleigh quotient residual bound. */ + + if (a2 < .563f) { + s = gam * (1.f - sqrt(a2)) / (a2 + 1.f); + } + } + } else if (*dmin__ == *dn2) { + +/* Case 5. */ + + *ttype = -5; + s = *dmin__ * .25f; + +/* Compute contribution to norm squared from I > NN-2. */ + + np = nn - (*pp << 1); + b1 = z__[np - 2]; + b2 = z__[np - 6]; + gam = *dn2; + if (z__[np - 8] > b2 || z__[np - 4] > b1) { + return 0; + } + a2 = z__[np - 8] / b2 * (z__[np - 4] / b1 + 1.f); + +/* Approximate contribution to norm squared from I < NN-2. */ + + if (*n0 - *i0 > 2) { + b2 = z__[nn - 13] / z__[nn - 15]; + a2 += b2; + i__1 = (*i0 << 2) - 1 + *pp; + for (i4 = nn - 17; i4 >= i__1; i4 += -4) { + if (b2 == 0.f) { + goto L40; + } + b1 = b2; + if (z__[i4] > z__[i4 - 2]) { + return 0; + } + b2 *= z__[i4] / z__[i4 - 2]; + a2 += b2; + if (dmax(b2,b1) * 100.f < a2 || .563f < a2) { + goto L40; + } +/* L30: */ + } +L40: + a2 *= 1.05f; + } + + if (a2 < .563f) { + s = gam * (1.f - sqrt(a2)) / (a2 + 1.f); + } + } else { + +/* Case 6, no information to guide us. */ + + if (*ttype == -6) { + g += (1.f - g) * .333f; + } else if (*ttype == -18) { + g = .083250000000000005f; + } else { + g = .25f; + } + s = g * *dmin__; + *ttype = -6; + } + + } else if (*n0in == *n0 + 1) { + +/* One eigenvalue just deflated. Use DMIN1, DN1 for DMIN and DN. */ + + if (*dmin1 == *dn1 && *dmin2 == *dn2) { + +/* Cases 7 and 8. */ + + *ttype = -7; + s = *dmin1 * .333f; + if (z__[nn - 5] > z__[nn - 7]) { + return 0; + } + b1 = z__[nn - 5] / z__[nn - 7]; + b2 = b1; + if (b2 == 0.f) { + goto L60; + } + i__1 = (*i0 << 2) - 1 + *pp; + for (i4 = (*n0 << 2) - 9 + *pp; i4 >= i__1; i4 += -4) { + a2 = b1; + if (z__[i4] > z__[i4 - 2]) { + return 0; + } + b1 *= z__[i4] / z__[i4 - 2]; + b2 += b1; + if (dmax(b1,a2) * 100.f < b2) { + goto L60; + } +/* L50: */ + } +L60: + b2 = sqrt(b2 * 1.05f); +/* Computing 2nd power */ + r__1 = b2; + a2 = *dmin1 / (r__1 * r__1 + 1.f); + gap2 = *dmin2 * .5f - a2; + if (gap2 > 0.f && gap2 > b2 * a2) { +/* Computing MAX */ + r__1 = s, r__2 = a2 * (1.f - a2 * 1.01f * (b2 / gap2) * b2); + s = dmax(r__1,r__2); + } else { +/* Computing MAX */ + r__1 = s, r__2 = a2 * (1.f - b2 * 1.01f); + s = dmax(r__1,r__2); + *ttype = -8; + } + } else { + +/* Case 9. */ + + s = *dmin1 * .25f; + if (*dmin1 == *dn1) { + s = *dmin1 * .5f; + } + *ttype = -9; + } + + } else if (*n0in == *n0 + 2) { + +/* + Two eigenvalues deflated. Use DMIN2, DN2 for DMIN and DN. + + Cases 10 and 11. +*/ + + if (*dmin2 == *dn2 && z__[nn - 5] * 2.f < z__[nn - 7]) { + *ttype = -10; + s = *dmin2 * .333f; + if (z__[nn - 5] > z__[nn - 7]) { + return 0; + } + b1 = z__[nn - 5] / z__[nn - 7]; + b2 = b1; + if (b2 == 0.f) { + goto L80; + } + i__1 = (*i0 << 2) - 1 + *pp; + for (i4 = (*n0 << 2) - 9 + *pp; i4 >= i__1; i4 += -4) { + if (z__[i4] > z__[i4 - 2]) { + return 0; + } + b1 *= z__[i4] / z__[i4 - 2]; + b2 += b1; + if (b1 * 100.f < b2) { + goto L80; + } +/* L70: */ + } +L80: + b2 = sqrt(b2 * 1.05f); +/* Computing 2nd power */ + r__1 = b2; + a2 = *dmin2 / (r__1 * r__1 + 1.f); + gap2 = z__[nn - 7] + z__[nn - 9] - sqrt(z__[nn - 11]) * sqrt(z__[ + nn - 9]) - a2; + if (gap2 > 0.f && gap2 > b2 * a2) { +/* Computing MAX */ + r__1 = s, r__2 = a2 * (1.f - a2 * 1.01f * (b2 / gap2) * b2); + s = dmax(r__1,r__2); + } else { +/* Computing MAX */ + r__1 = s, r__2 = a2 * (1.f - b2 * 1.01f); + s = dmax(r__1,r__2); + } + } else { + s = *dmin2 * .25f; + *ttype = -11; + } + } else if (*n0in > *n0 + 2) { + +/* Case 12, more than two eigenvalues deflated. No information. */ + + s = 0.f; + *ttype = -12; + } + + *tau = s; + return 0; + +/* End of SLASQ4 */ + +} /* slasq4_ */ + +/* Subroutine */ int slasq5_(integer *i0, integer *n0, real *z__, integer *pp, + real *tau, real *dmin__, real *dmin1, real *dmin2, real *dn, real * + dnm1, real *dnm2, logical *ieee) +{ + /* System generated locals */ + integer i__1; + real r__1, r__2; + + /* Local variables */ + static real d__; + static integer j4, j4p2; + static real emin, temp; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + May 17, 2000 + + + Purpose + ======= + + SLASQ5 computes one dqds transform in ping-pong form, one + version for IEEE machines another for non IEEE machines. + + Arguments + ========= + + I0 (input) INTEGER + First index. + + N0 (input) INTEGER + Last index. + + Z (input) REAL array, dimension ( 4*N ) + Z holds the qd array. EMIN is stored in Z(4*N0) to avoid + an extra argument. + + PP (input) INTEGER + PP=0 for ping, PP=1 for pong. + + TAU (input) REAL + This is the shift. + + DMIN (output) REAL + Minimum value of d. + + DMIN1 (output) REAL + Minimum value of d, excluding D( N0 ). + + DMIN2 (output) REAL + Minimum value of d, excluding D( N0 ) and D( N0-1 ). + + DN (output) REAL + d(N0), the last value of d. + + DNM1 (output) REAL + d(N0-1). + + DNM2 (output) REAL + d(N0-2). + + IEEE (input) LOGICAL + Flag for IEEE or non IEEE arithmetic. + + ===================================================================== +*/ + + + /* Parameter adjustments */ + --z__; + + /* Function Body */ + if (*n0 - *i0 - 1 <= 0) { + return 0; + } + + j4 = (*i0 << 2) + *pp - 3; + emin = z__[j4 + 4]; + d__ = z__[j4] - *tau; + *dmin__ = d__; + *dmin1 = -z__[j4]; + + if (*ieee) { + +/* Code for IEEE arithmetic. */ + + if (*pp == 0) { + i__1 = *n0 - 3 << 2; + for (j4 = *i0 << 2; j4 <= i__1; j4 += 4) { + z__[j4 - 2] = d__ + z__[j4 - 1]; + temp = z__[j4 + 1] / z__[j4 - 2]; + d__ = d__ * temp - *tau; + *dmin__ = dmin(*dmin__,d__); + z__[j4] = z__[j4 - 1] * temp; +/* Computing MIN */ + r__1 = z__[j4]; + emin = dmin(r__1,emin); +/* L10: */ + } + } else { + i__1 = *n0 - 3 << 2; + for (j4 = *i0 << 2; j4 <= i__1; j4 += 4) { + z__[j4 - 3] = d__ + z__[j4]; + temp = z__[j4 + 2] / z__[j4 - 3]; + d__ = d__ * temp - *tau; + *dmin__ = dmin(*dmin__,d__); + z__[j4 - 1] = z__[j4] * temp; +/* Computing MIN */ + r__1 = z__[j4 - 1]; + emin = dmin(r__1,emin); +/* L20: */ + } + } + +/* Unroll last two steps. */ + + *dnm2 = d__; + *dmin2 = *dmin__; + j4 = (*n0 - 2 << 2) - *pp; + j4p2 = j4 + (*pp << 1) - 1; + z__[j4 - 2] = *dnm2 + z__[j4p2]; + z__[j4] = z__[j4p2 + 2] * (z__[j4p2] / z__[j4 - 2]); + *dnm1 = z__[j4p2 + 2] * (*dnm2 / z__[j4 - 2]) - *tau; + *dmin__ = dmin(*dmin__,*dnm1); + + *dmin1 = *dmin__; + j4 += 4; + j4p2 = j4 + (*pp << 1) - 1; + z__[j4 - 2] = *dnm1 + z__[j4p2]; + z__[j4] = z__[j4p2 + 2] * (z__[j4p2] / z__[j4 - 2]); + *dn = z__[j4p2 + 2] * (*dnm1 / z__[j4 - 2]) - *tau; + *dmin__ = dmin(*dmin__,*dn); + + } else { + +/* Code for non IEEE arithmetic. */ + + if (*pp == 0) { + i__1 = *n0 - 3 << 2; + for (j4 = *i0 << 2; j4 <= i__1; j4 += 4) { + z__[j4 - 2] = d__ + z__[j4 - 1]; + if (d__ < 0.f) { + return 0; + } else { + z__[j4] = z__[j4 + 1] * (z__[j4 - 1] / z__[j4 - 2]); + d__ = z__[j4 + 1] * (d__ / z__[j4 - 2]) - *tau; + } + *dmin__ = dmin(*dmin__,d__); +/* Computing MIN */ + r__1 = emin, r__2 = z__[j4]; + emin = dmin(r__1,r__2); +/* L30: */ + } + } else { + i__1 = *n0 - 3 << 2; + for (j4 = *i0 << 2; j4 <= i__1; j4 += 4) { + z__[j4 - 3] = d__ + z__[j4]; + if (d__ < 0.f) { + return 0; + } else { + z__[j4 - 1] = z__[j4 + 2] * (z__[j4] / z__[j4 - 3]); + d__ = z__[j4 + 2] * (d__ / z__[j4 - 3]) - *tau; + } + *dmin__ = dmin(*dmin__,d__); +/* Computing MIN */ + r__1 = emin, r__2 = z__[j4 - 1]; + emin = dmin(r__1,r__2); +/* L40: */ + } + } + +/* Unroll last two steps. */ + + *dnm2 = d__; + *dmin2 = *dmin__; + j4 = (*n0 - 2 << 2) - *pp; + j4p2 = j4 + (*pp << 1) - 1; + z__[j4 - 2] = *dnm2 + z__[j4p2]; + if (*dnm2 < 0.f) { + return 0; + } else { + z__[j4] = z__[j4p2 + 2] * (z__[j4p2] / z__[j4 - 2]); + *dnm1 = z__[j4p2 + 2] * (*dnm2 / z__[j4 - 2]) - *tau; + } + *dmin__ = dmin(*dmin__,*dnm1); + + *dmin1 = *dmin__; + j4 += 4; + j4p2 = j4 + (*pp << 1) - 1; + z__[j4 - 2] = *dnm1 + z__[j4p2]; + if (*dnm1 < 0.f) { + return 0; + } else { + z__[j4] = z__[j4p2 + 2] * (z__[j4p2] / z__[j4 - 2]); + *dn = z__[j4p2 + 2] * (*dnm1 / z__[j4 - 2]) - *tau; + } + *dmin__ = dmin(*dmin__,*dn); + + } + + z__[j4 + 2] = *dn; + z__[(*n0 << 2) - *pp] = emin; + return 0; + +/* End of SLASQ5 */ + +} /* slasq5_ */ + +/* Subroutine */ int slasq6_(integer *i0, integer *n0, real *z__, integer *pp, + real *dmin__, real *dmin1, real *dmin2, real *dn, real *dnm1, real * + dnm2) +{ + /* System generated locals */ + integer i__1; + real r__1, r__2; + + /* Local variables */ + static real d__; + static integer j4, j4p2; + static real emin, temp; + extern doublereal slamch_(char *); + static real safmin; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1999 + + + Purpose + ======= + + SLASQ6 computes one dqd (shift equal to zero) transform in + ping-pong form, with protection against underflow and overflow. + + Arguments + ========= + + I0 (input) INTEGER + First index. + + N0 (input) INTEGER + Last index. + + Z (input) REAL array, dimension ( 4*N ) + Z holds the qd array. EMIN is stored in Z(4*N0) to avoid + an extra argument. + + PP (input) INTEGER + PP=0 for ping, PP=1 for pong. + + DMIN (output) REAL + Minimum value of d. + + DMIN1 (output) REAL + Minimum value of d, excluding D( N0 ). + + DMIN2 (output) REAL + Minimum value of d, excluding D( N0 ) and D( N0-1 ). + + DN (output) REAL + d(N0), the last value of d. + + DNM1 (output) REAL + d(N0-1). + + DNM2 (output) REAL + d(N0-2). + + ===================================================================== +*/ + + + /* Parameter adjustments */ + --z__; + + /* Function Body */ + if (*n0 - *i0 - 1 <= 0) { + return 0; + } + + safmin = slamch_("Safe minimum"); + j4 = (*i0 << 2) + *pp - 3; + emin = z__[j4 + 4]; + d__ = z__[j4]; + *dmin__ = d__; + + if (*pp == 0) { + i__1 = *n0 - 3 << 2; + for (j4 = *i0 << 2; j4 <= i__1; j4 += 4) { + z__[j4 - 2] = d__ + z__[j4 - 1]; + if (z__[j4 - 2] == 0.f) { + z__[j4] = 0.f; + d__ = z__[j4 + 1]; + *dmin__ = d__; + emin = 0.f; + } else if (safmin * z__[j4 + 1] < z__[j4 - 2] && safmin * z__[j4 + - 2] < z__[j4 + 1]) { + temp = z__[j4 + 1] / z__[j4 - 2]; + z__[j4] = z__[j4 - 1] * temp; + d__ *= temp; + } else { + z__[j4] = z__[j4 + 1] * (z__[j4 - 1] / z__[j4 - 2]); + d__ = z__[j4 + 1] * (d__ / z__[j4 - 2]); + } + *dmin__ = dmin(*dmin__,d__); +/* Computing MIN */ + r__1 = emin, r__2 = z__[j4]; + emin = dmin(r__1,r__2); +/* L10: */ + } + } else { + i__1 = *n0 - 3 << 2; + for (j4 = *i0 << 2; j4 <= i__1; j4 += 4) { + z__[j4 - 3] = d__ + z__[j4]; + if (z__[j4 - 3] == 0.f) { + z__[j4 - 1] = 0.f; + d__ = z__[j4 + 2]; + *dmin__ = d__; + emin = 0.f; + } else if (safmin * z__[j4 + 2] < z__[j4 - 3] && safmin * z__[j4 + - 3] < z__[j4 + 2]) { + temp = z__[j4 + 2] / z__[j4 - 3]; + z__[j4 - 1] = z__[j4] * temp; + d__ *= temp; + } else { + z__[j4 - 1] = z__[j4 + 2] * (z__[j4] / z__[j4 - 3]); + d__ = z__[j4 + 2] * (d__ / z__[j4 - 3]); + } + *dmin__ = dmin(*dmin__,d__); +/* Computing MIN */ + r__1 = emin, r__2 = z__[j4 - 1]; + emin = dmin(r__1,r__2); +/* L20: */ + } + } + +/* Unroll last two steps. */ + + *dnm2 = d__; + *dmin2 = *dmin__; + j4 = (*n0 - 2 << 2) - *pp; + j4p2 = j4 + (*pp << 1) - 1; + z__[j4 - 2] = *dnm2 + z__[j4p2]; + if (z__[j4 - 2] == 0.f) { + z__[j4] = 0.f; + *dnm1 = z__[j4p2 + 2]; + *dmin__ = *dnm1; + emin = 0.f; + } else if (safmin * z__[j4p2 + 2] < z__[j4 - 2] && safmin * z__[j4 - 2] < + z__[j4p2 + 2]) { + temp = z__[j4p2 + 2] / z__[j4 - 2]; + z__[j4] = z__[j4p2] * temp; + *dnm1 = *dnm2 * temp; + } else { + z__[j4] = z__[j4p2 + 2] * (z__[j4p2] / z__[j4 - 2]); + *dnm1 = z__[j4p2 + 2] * (*dnm2 / z__[j4 - 2]); + } + *dmin__ = dmin(*dmin__,*dnm1); + + *dmin1 = *dmin__; + j4 += 4; + j4p2 = j4 + (*pp << 1) - 1; + z__[j4 - 2] = *dnm1 + z__[j4p2]; + if (z__[j4 - 2] == 0.f) { + z__[j4] = 0.f; + *dn = z__[j4p2 + 2]; + *dmin__ = *dn; + emin = 0.f; + } else if (safmin * z__[j4p2 + 2] < z__[j4 - 2] && safmin * z__[j4 - 2] < + z__[j4p2 + 2]) { + temp = z__[j4p2 + 2] / z__[j4 - 2]; + z__[j4] = z__[j4p2] * temp; + *dn = *dnm1 * temp; + } else { + z__[j4] = z__[j4p2 + 2] * (z__[j4p2] / z__[j4 - 2]); + *dn = z__[j4p2 + 2] * (*dnm1 / z__[j4 - 2]); + } + *dmin__ = dmin(*dmin__,*dn); + + z__[j4 + 2] = *dn; + z__[(*n0 << 2) - *pp] = emin; + return 0; + +/* End of SLASQ6 */ + +} /* slasq6_ */ + +/* Subroutine */ int slasr_(char *side, char *pivot, char *direct, integer *m, + integer *n, real *c__, real *s, real *a, integer *lda) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2; + + /* Local variables */ + static integer i__, j, info; + static real temp; + extern logical lsame_(char *, char *); + static real ctemp, stemp; + extern /* Subroutine */ int xerbla_(char *, integer *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLASR performs the transformation + + A := P*A, when SIDE = 'L' or 'l' ( Left-hand side ) + + A := A*P', when SIDE = 'R' or 'r' ( Right-hand side ) + + where A is an m by n real matrix and P is an orthogonal matrix, + consisting of a sequence of plane rotations determined by the + parameters PIVOT and DIRECT as follows ( z = m when SIDE = 'L' or 'l' + and z = n when SIDE = 'R' or 'r' ): + + When DIRECT = 'F' or 'f' ( Forward sequence ) then + + P = P( z - 1 )*...*P( 2 )*P( 1 ), + + and when DIRECT = 'B' or 'b' ( Backward sequence ) then + + P = P( 1 )*P( 2 )*...*P( z - 1 ), + + where P( k ) is a plane rotation matrix for the following planes: + + when PIVOT = 'V' or 'v' ( Variable pivot ), + the plane ( k, k + 1 ) + + when PIVOT = 'T' or 't' ( Top pivot ), + the plane ( 1, k + 1 ) + + when PIVOT = 'B' or 'b' ( Bottom pivot ), + the plane ( k, z ) + + c( k ) and s( k ) must contain the cosine and sine that define the + matrix P( k ). The two by two plane rotation part of the matrix + P( k ), R( k ), is assumed to be of the form + + R( k ) = ( c( k ) s( k ) ). + ( -s( k ) c( k ) ) + + This version vectorises across rows of the array A when SIDE = 'L'. + + Arguments + ========= + + SIDE (input) CHARACTER*1 + Specifies whether the plane rotation matrix P is applied to + A on the left or the right. + = 'L': Left, compute A := P*A + = 'R': Right, compute A:= A*P' + + DIRECT (input) CHARACTER*1 + Specifies whether P is a forward or backward sequence of + plane rotations. + = 'F': Forward, P = P( z - 1 )*...*P( 2 )*P( 1 ) + = 'B': Backward, P = P( 1 )*P( 2 )*...*P( z - 1 ) + + PIVOT (input) CHARACTER*1 + Specifies the plane for which P(k) is a plane rotation + matrix. + = 'V': Variable pivot, the plane (k,k+1) + = 'T': Top pivot, the plane (1,k+1) + = 'B': Bottom pivot, the plane (k,z) + + M (input) INTEGER + The number of rows of the matrix A. If m <= 1, an immediate + return is effected. + + N (input) INTEGER + The number of columns of the matrix A. If n <= 1, an + immediate return is effected. + + C, S (input) REAL arrays, dimension + (M-1) if SIDE = 'L' + (N-1) if SIDE = 'R' + c(k) and s(k) contain the cosine and sine that define the + matrix P(k). The two by two plane rotation part of the + matrix P(k), R(k), is assumed to be of the form + R( k ) = ( c( k ) s( k ) ). + ( -s( k ) c( k ) ) + + A (input/output) REAL array, dimension (LDA,N) + The m by n matrix A. On exit, A is overwritten by P*A if + SIDE = 'R' or by A*P' if SIDE = 'L'. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + ===================================================================== + + + Test the input parameters +*/ + + /* Parameter adjustments */ + --c__; + --s; + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + + /* Function Body */ + info = 0; + if (! (lsame_(side, "L") || lsame_(side, "R"))) { + info = 1; + } else if (! (lsame_(pivot, "V") || lsame_(pivot, + "T") || lsame_(pivot, "B"))) { + info = 2; + } else if (! (lsame_(direct, "F") || lsame_(direct, + "B"))) { + info = 3; + } else if (*m < 0) { + info = 4; + } else if (*n < 0) { + info = 5; + } else if (*lda < max(1,*m)) { + info = 9; + } + if (info != 0) { + xerbla_("SLASR ", &info); + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0) { + return 0; + } + if (lsame_(side, "L")) { + +/* Form P * A */ + + if (lsame_(pivot, "V")) { + if (lsame_(direct, "F")) { + i__1 = *m - 1; + for (j = 1; j <= i__1; ++j) { + ctemp = c__[j]; + stemp = s[j]; + if (ctemp != 1.f || stemp != 0.f) { + i__2 = *n; + for (i__ = 1; i__ <= i__2; ++i__) { + temp = a[j + 1 + i__ * a_dim1]; + a[j + 1 + i__ * a_dim1] = ctemp * temp - stemp * + a[j + i__ * a_dim1]; + a[j + i__ * a_dim1] = stemp * temp + ctemp * a[j + + i__ * a_dim1]; +/* L10: */ + } + } +/* L20: */ + } + } else if (lsame_(direct, "B")) { + for (j = *m - 1; j >= 1; --j) { + ctemp = c__[j]; + stemp = s[j]; + if (ctemp != 1.f || stemp != 0.f) { + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + temp = a[j + 1 + i__ * a_dim1]; + a[j + 1 + i__ * a_dim1] = ctemp * temp - stemp * + a[j + i__ * a_dim1]; + a[j + i__ * a_dim1] = stemp * temp + ctemp * a[j + + i__ * a_dim1]; +/* L30: */ + } + } +/* L40: */ + } + } + } else if (lsame_(pivot, "T")) { + if (lsame_(direct, "F")) { + i__1 = *m; + for (j = 2; j <= i__1; ++j) { + ctemp = c__[j - 1]; + stemp = s[j - 1]; + if (ctemp != 1.f || stemp != 0.f) { + i__2 = *n; + for (i__ = 1; i__ <= i__2; ++i__) { + temp = a[j + i__ * a_dim1]; + a[j + i__ * a_dim1] = ctemp * temp - stemp * a[ + i__ * a_dim1 + 1]; + a[i__ * a_dim1 + 1] = stemp * temp + ctemp * a[ + i__ * a_dim1 + 1]; +/* L50: */ + } + } +/* L60: */ + } + } else if (lsame_(direct, "B")) { + for (j = *m; j >= 2; --j) { + ctemp = c__[j - 1]; + stemp = s[j - 1]; + if (ctemp != 1.f || stemp != 0.f) { + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + temp = a[j + i__ * a_dim1]; + a[j + i__ * a_dim1] = ctemp * temp - stemp * a[ + i__ * a_dim1 + 1]; + a[i__ * a_dim1 + 1] = stemp * temp + ctemp * a[ + i__ * a_dim1 + 1]; +/* L70: */ + } + } +/* L80: */ + } + } + } else if (lsame_(pivot, "B")) { + if (lsame_(direct, "F")) { + i__1 = *m - 1; + for (j = 1; j <= i__1; ++j) { + ctemp = c__[j]; + stemp = s[j]; + if (ctemp != 1.f || stemp != 0.f) { + i__2 = *n; + for (i__ = 1; i__ <= i__2; ++i__) { + temp = a[j + i__ * a_dim1]; + a[j + i__ * a_dim1] = stemp * a[*m + i__ * a_dim1] + + ctemp * temp; + a[*m + i__ * a_dim1] = ctemp * a[*m + i__ * + a_dim1] - stemp * temp; +/* L90: */ + } + } +/* L100: */ + } + } else if (lsame_(direct, "B")) { + for (j = *m - 1; j >= 1; --j) { + ctemp = c__[j]; + stemp = s[j]; + if (ctemp != 1.f || stemp != 0.f) { + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + temp = a[j + i__ * a_dim1]; + a[j + i__ * a_dim1] = stemp * a[*m + i__ * a_dim1] + + ctemp * temp; + a[*m + i__ * a_dim1] = ctemp * a[*m + i__ * + a_dim1] - stemp * temp; +/* L110: */ + } + } +/* L120: */ + } + } + } + } else if (lsame_(side, "R")) { + +/* Form A * P' */ + + if (lsame_(pivot, "V")) { + if (lsame_(direct, "F")) { + i__1 = *n - 1; + for (j = 1; j <= i__1; ++j) { + ctemp = c__[j]; + stemp = s[j]; + if (ctemp != 1.f || stemp != 0.f) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + temp = a[i__ + (j + 1) * a_dim1]; + a[i__ + (j + 1) * a_dim1] = ctemp * temp - stemp * + a[i__ + j * a_dim1]; + a[i__ + j * a_dim1] = stemp * temp + ctemp * a[ + i__ + j * a_dim1]; +/* L130: */ + } + } +/* L140: */ + } + } else if (lsame_(direct, "B")) { + for (j = *n - 1; j >= 1; --j) { + ctemp = c__[j]; + stemp = s[j]; + if (ctemp != 1.f || stemp != 0.f) { + i__1 = *m; + for (i__ = 1; i__ <= i__1; ++i__) { + temp = a[i__ + (j + 1) * a_dim1]; + a[i__ + (j + 1) * a_dim1] = ctemp * temp - stemp * + a[i__ + j * a_dim1]; + a[i__ + j * a_dim1] = stemp * temp + ctemp * a[ + i__ + j * a_dim1]; +/* L150: */ + } + } +/* L160: */ + } + } + } else if (lsame_(pivot, "T")) { + if (lsame_(direct, "F")) { + i__1 = *n; + for (j = 2; j <= i__1; ++j) { + ctemp = c__[j - 1]; + stemp = s[j - 1]; + if (ctemp != 1.f || stemp != 0.f) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + temp = a[i__ + j * a_dim1]; + a[i__ + j * a_dim1] = ctemp * temp - stemp * a[ + i__ + a_dim1]; + a[i__ + a_dim1] = stemp * temp + ctemp * a[i__ + + a_dim1]; +/* L170: */ + } + } +/* L180: */ + } + } else if (lsame_(direct, "B")) { + for (j = *n; j >= 2; --j) { + ctemp = c__[j - 1]; + stemp = s[j - 1]; + if (ctemp != 1.f || stemp != 0.f) { + i__1 = *m; + for (i__ = 1; i__ <= i__1; ++i__) { + temp = a[i__ + j * a_dim1]; + a[i__ + j * a_dim1] = ctemp * temp - stemp * a[ + i__ + a_dim1]; + a[i__ + a_dim1] = stemp * temp + ctemp * a[i__ + + a_dim1]; +/* L190: */ + } + } +/* L200: */ + } + } + } else if (lsame_(pivot, "B")) { + if (lsame_(direct, "F")) { + i__1 = *n - 1; + for (j = 1; j <= i__1; ++j) { + ctemp = c__[j]; + stemp = s[j]; + if (ctemp != 1.f || stemp != 0.f) { + i__2 = *m; + for (i__ = 1; i__ <= i__2; ++i__) { + temp = a[i__ + j * a_dim1]; + a[i__ + j * a_dim1] = stemp * a[i__ + *n * a_dim1] + + ctemp * temp; + a[i__ + *n * a_dim1] = ctemp * a[i__ + *n * + a_dim1] - stemp * temp; +/* L210: */ + } + } +/* L220: */ + } + } else if (lsame_(direct, "B")) { + for (j = *n - 1; j >= 1; --j) { + ctemp = c__[j]; + stemp = s[j]; + if (ctemp != 1.f || stemp != 0.f) { + i__1 = *m; + for (i__ = 1; i__ <= i__1; ++i__) { + temp = a[i__ + j * a_dim1]; + a[i__ + j * a_dim1] = stemp * a[i__ + *n * a_dim1] + + ctemp * temp; + a[i__ + *n * a_dim1] = ctemp * a[i__ + *n * + a_dim1] - stemp * temp; +/* L230: */ + } + } +/* L240: */ + } + } + } + } + + return 0; + +/* End of SLASR */ + +} /* slasr_ */ + +/* Subroutine */ int slasrt_(char *id, integer *n, real *d__, integer *info) +{ + /* System generated locals */ + integer i__1, i__2; + + /* Local variables */ + static integer i__, j; + static real d1, d2, d3; + static integer dir; + static real tmp; + static integer endd; + extern logical lsame_(char *, char *); + static integer stack[64] /* was [2][32] */; + static real dmnmx; + static integer start; + extern /* Subroutine */ int xerbla_(char *, integer *); + static integer stkpnt; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + September 30, 1994 + + + Purpose + ======= + + Sort the numbers in D in increasing order (if ID = 'I') or + in decreasing order (if ID = 'D' ). + + Use Quick Sort, reverting to Insertion sort on arrays of + size <= 20. Dimension of STACK limits N to about 2**32. + + Arguments + ========= + + ID (input) CHARACTER*1 + = 'I': sort D in increasing order; + = 'D': sort D in decreasing order. + + N (input) INTEGER + The length of the array D. + + D (input/output) REAL array, dimension (N) + On entry, the array to be sorted. + On exit, D has been sorted into increasing order + (D(1) <= ... <= D(N) ) or into decreasing order + (D(1) >= ... >= D(N) ), depending on ID. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input paramters. +*/ + + /* Parameter adjustments */ + --d__; + + /* Function Body */ + *info = 0; + dir = -1; + if (lsame_(id, "D")) { + dir = 0; + } else if (lsame_(id, "I")) { + dir = 1; + } + if (dir == -1) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLASRT", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n <= 1) { + return 0; + } + + stkpnt = 1; + stack[0] = 1; + stack[1] = *n; +L10: + start = stack[(stkpnt << 1) - 2]; + endd = stack[(stkpnt << 1) - 1]; + --stkpnt; + if (endd - start <= 20 && endd - start > 0) { + +/* Do Insertion sort on D( START:ENDD ) */ + + if (dir == 0) { + +/* Sort into decreasing order */ + + i__1 = endd; + for (i__ = start + 1; i__ <= i__1; ++i__) { + i__2 = start + 1; + for (j = i__; j >= i__2; --j) { + if (d__[j] > d__[j - 1]) { + dmnmx = d__[j]; + d__[j] = d__[j - 1]; + d__[j - 1] = dmnmx; + } else { + goto L30; + } +/* L20: */ + } +L30: + ; + } + + } else { + +/* Sort into increasing order */ + + i__1 = endd; + for (i__ = start + 1; i__ <= i__1; ++i__) { + i__2 = start + 1; + for (j = i__; j >= i__2; --j) { + if (d__[j] < d__[j - 1]) { + dmnmx = d__[j]; + d__[j] = d__[j - 1]; + d__[j - 1] = dmnmx; + } else { + goto L50; + } +/* L40: */ + } +L50: + ; + } + + } + + } else if (endd - start > 20) { + +/* + Partition D( START:ENDD ) and stack parts, largest one first + + Choose partition entry as median of 3 +*/ + + d1 = d__[start]; + d2 = d__[endd]; + i__ = (start + endd) / 2; + d3 = d__[i__]; + if (d1 < d2) { + if (d3 < d1) { + dmnmx = d1; + } else if (d3 < d2) { + dmnmx = d3; + } else { + dmnmx = d2; + } + } else { + if (d3 < d2) { + dmnmx = d2; + } else if (d3 < d1) { + dmnmx = d3; + } else { + dmnmx = d1; + } + } + + if (dir == 0) { + +/* Sort into decreasing order */ + + i__ = start - 1; + j = endd + 1; +L60: +L70: + --j; + if (d__[j] < dmnmx) { + goto L70; + } +L80: + ++i__; + if (d__[i__] > dmnmx) { + goto L80; + } + if (i__ < j) { + tmp = d__[i__]; + d__[i__] = d__[j]; + d__[j] = tmp; + goto L60; + } + if (j - start > endd - j - 1) { + ++stkpnt; + stack[(stkpnt << 1) - 2] = start; + stack[(stkpnt << 1) - 1] = j; + ++stkpnt; + stack[(stkpnt << 1) - 2] = j + 1; + stack[(stkpnt << 1) - 1] = endd; + } else { + ++stkpnt; + stack[(stkpnt << 1) - 2] = j + 1; + stack[(stkpnt << 1) - 1] = endd; + ++stkpnt; + stack[(stkpnt << 1) - 2] = start; + stack[(stkpnt << 1) - 1] = j; + } + } else { + +/* Sort into increasing order */ + + i__ = start - 1; + j = endd + 1; +L90: +L100: + --j; + if (d__[j] > dmnmx) { + goto L100; + } +L110: + ++i__; + if (d__[i__] < dmnmx) { + goto L110; + } + if (i__ < j) { + tmp = d__[i__]; + d__[i__] = d__[j]; + d__[j] = tmp; + goto L90; + } + if (j - start > endd - j - 1) { + ++stkpnt; + stack[(stkpnt << 1) - 2] = start; + stack[(stkpnt << 1) - 1] = j; + ++stkpnt; + stack[(stkpnt << 1) - 2] = j + 1; + stack[(stkpnt << 1) - 1] = endd; + } else { + ++stkpnt; + stack[(stkpnt << 1) - 2] = j + 1; + stack[(stkpnt << 1) - 1] = endd; + ++stkpnt; + stack[(stkpnt << 1) - 2] = start; + stack[(stkpnt << 1) - 1] = j; + } + } + } + if (stkpnt > 0) { + goto L10; + } + return 0; + +/* End of SLASRT */ + +} /* slasrt_ */ + +/* Subroutine */ int slassq_(integer *n, real *x, integer *incx, real *scale, + real *sumsq) +{ + /* System generated locals */ + integer i__1, i__2; + real r__1; + + /* Local variables */ + static integer ix; + static real absxi; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SLASSQ returns the values scl and smsq such that + + ( scl**2 )*smsq = x( 1 )**2 +...+ x( n )**2 + ( scale**2 )*sumsq, + + where x( i ) = X( 1 + ( i - 1 )*INCX ). The value of sumsq is + assumed to be non-negative and scl returns the value + + scl = max( scale, abs( x( i ) ) ). + + scale and sumsq must be supplied in SCALE and SUMSQ and + scl and smsq are overwritten on SCALE and SUMSQ respectively. + + The routine makes only one pass through the vector x. + + Arguments + ========= + + N (input) INTEGER + The number of elements to be used from the vector X. + + X (input) REAL array, dimension (N) + The vector for which a scaled sum of squares is computed. + x( i ) = X( 1 + ( i - 1 )*INCX ), 1 <= i <= n. + + INCX (input) INTEGER + The increment between successive values of the vector X. + INCX > 0. + + SCALE (input/output) REAL + On entry, the value scale in the equation above. + On exit, SCALE is overwritten with scl , the scaling factor + for the sum of squares. + + SUMSQ (input/output) REAL + On entry, the value sumsq in the equation above. + On exit, SUMSQ is overwritten with smsq , the basic sum of + squares from which scl has been factored out. + + ===================================================================== +*/ + + + /* Parameter adjustments */ + --x; + + /* Function Body */ + if (*n > 0) { + i__1 = (*n - 1) * *incx + 1; + i__2 = *incx; + for (ix = 1; i__2 < 0 ? ix >= i__1 : ix <= i__1; ix += i__2) { + if (x[ix] != 0.f) { + absxi = (r__1 = x[ix], dabs(r__1)); + if (*scale < absxi) { +/* Computing 2nd power */ + r__1 = *scale / absxi; + *sumsq = *sumsq * (r__1 * r__1) + 1; + *scale = absxi; + } else { +/* Computing 2nd power */ + r__1 = absxi / *scale; + *sumsq += r__1 * r__1; + } + } +/* L10: */ + } + } + return 0; + +/* End of SLASSQ */ + +} /* slassq_ */ + +/* Subroutine */ int slasv2_(real *f, real *g, real *h__, real *ssmin, real * + ssmax, real *snr, real *csr, real *snl, real *csl) +{ + /* System generated locals */ + real r__1; + + /* Builtin functions */ + double sqrt(doublereal), r_sign(real *, real *); + + /* Local variables */ + static real a, d__, l, m, r__, s, t, fa, ga, ha, ft, gt, ht, mm, tt, clt, + crt, slt, srt; + static integer pmax; + static real temp; + static logical swap; + static real tsign; + static logical gasmal; + extern doublereal slamch_(char *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLASV2 computes the singular value decomposition of a 2-by-2 + triangular matrix + [ F G ] + [ 0 H ]. + On return, abs(SSMAX) is the larger singular value, abs(SSMIN) is the + smaller singular value, and (CSL,SNL) and (CSR,SNR) are the left and + right singular vectors for abs(SSMAX), giving the decomposition + + [ CSL SNL ] [ F G ] [ CSR -SNR ] = [ SSMAX 0 ] + [-SNL CSL ] [ 0 H ] [ SNR CSR ] [ 0 SSMIN ]. + + Arguments + ========= + + F (input) REAL + The (1,1) element of the 2-by-2 matrix. + + G (input) REAL + The (1,2) element of the 2-by-2 matrix. + + H (input) REAL + The (2,2) element of the 2-by-2 matrix. + + SSMIN (output) REAL + abs(SSMIN) is the smaller singular value. + + SSMAX (output) REAL + abs(SSMAX) is the larger singular value. + + SNL (output) REAL + CSL (output) REAL + The vector (CSL, SNL) is a unit left singular vector for the + singular value abs(SSMAX). + + SNR (output) REAL + CSR (output) REAL + The vector (CSR, SNR) is a unit right singular vector for the + singular value abs(SSMAX). + + Further Details + =============== + + Any input parameter may be aliased with any output parameter. + + Barring over/underflow and assuming a guard digit in subtraction, all + output quantities are correct to within a few units in the last + place (ulps). + + In IEEE arithmetic, the code works correctly if one matrix element is + infinite. + + Overflow will not occur unless the largest singular value itself + overflows or is within a few ulps of overflow. (On machines with + partial overflow, like the Cray, overflow may occur if the largest + singular value is within a factor of 2 of overflow.) + + Underflow is harmless if underflow is gradual. Otherwise, results + may correspond to a matrix modified by perturbations of size near + the underflow threshold. + + ===================================================================== +*/ + + + ft = *f; + fa = dabs(ft); + ht = *h__; + ha = dabs(*h__); + +/* + PMAX points to the maximum absolute element of matrix + PMAX = 1 if F largest in absolute values + PMAX = 2 if G largest in absolute values + PMAX = 3 if H largest in absolute values +*/ + + pmax = 1; + swap = ha > fa; + if (swap) { + pmax = 3; + temp = ft; + ft = ht; + ht = temp; + temp = fa; + fa = ha; + ha = temp; + +/* Now FA .ge. HA */ + + } + gt = *g; + ga = dabs(gt); + if (ga == 0.f) { + +/* Diagonal matrix */ + + *ssmin = ha; + *ssmax = fa; + clt = 1.f; + crt = 1.f; + slt = 0.f; + srt = 0.f; + } else { + gasmal = TRUE_; + if (ga > fa) { + pmax = 2; + if (fa / ga < slamch_("EPS")) { + +/* Case of very large GA */ + + gasmal = FALSE_; + *ssmax = ga; + if (ha > 1.f) { + *ssmin = fa / (ga / ha); + } else { + *ssmin = fa / ga * ha; + } + clt = 1.f; + slt = ht / gt; + srt = 1.f; + crt = ft / gt; + } + } + if (gasmal) { + +/* Normal case */ + + d__ = fa - ha; + if (d__ == fa) { + +/* Copes with infinite F or H */ + + l = 1.f; + } else { + l = d__ / fa; + } + +/* Note that 0 .le. L .le. 1 */ + + m = gt / ft; + +/* Note that abs(M) .le. 1/macheps */ + + t = 2.f - l; + +/* Note that T .ge. 1 */ + + mm = m * m; + tt = t * t; + s = sqrt(tt + mm); + +/* Note that 1 .le. S .le. 1 + 1/macheps */ + + if (l == 0.f) { + r__ = dabs(m); + } else { + r__ = sqrt(l * l + mm); + } + +/* Note that 0 .le. R .le. 1 + 1/macheps */ + + a = (s + r__) * .5f; + +/* Note that 1 .le. A .le. 1 + abs(M) */ + + *ssmin = ha / a; + *ssmax = fa * a; + if (mm == 0.f) { + +/* Note that M is very tiny */ + + if (l == 0.f) { + t = r_sign(&c_b2521, &ft) * r_sign(&c_b15, >); + } else { + t = gt / r_sign(&d__, &ft) + m / t; + } + } else { + t = (m / (s + t) + m / (r__ + l)) * (a + 1.f); + } + l = sqrt(t * t + 4.f); + crt = 2.f / l; + srt = t / l; + clt = (crt + srt * m) / a; + slt = ht / ft * srt / a; + } + } + if (swap) { + *csl = srt; + *snl = crt; + *csr = slt; + *snr = clt; + } else { + *csl = clt; + *snl = slt; + *csr = crt; + *snr = srt; + } + +/* Correct signs of SSMAX and SSMIN */ + + if (pmax == 1) { + tsign = r_sign(&c_b15, csr) * r_sign(&c_b15, csl) * r_sign(&c_b15, f); + } + if (pmax == 2) { + tsign = r_sign(&c_b15, snr) * r_sign(&c_b15, csl) * r_sign(&c_b15, g); + } + if (pmax == 3) { + tsign = r_sign(&c_b15, snr) * r_sign(&c_b15, snl) * r_sign(&c_b15, + h__); + } + *ssmax = r_sign(ssmax, &tsign); + r__1 = tsign * r_sign(&c_b15, f) * r_sign(&c_b15, h__); + *ssmin = r_sign(ssmin, &r__1); + return 0; + +/* End of SLASV2 */ + +} /* slasv2_ */ + +/* Subroutine */ int slaswp_(integer *n, real *a, integer *lda, integer *k1, + integer *k2, integer *ipiv, integer *incx) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3, i__4; + + /* Local variables */ + static integer i__, j, k, i1, i2, n32, ip, ix, ix0, inc; + static real temp; + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SLASWP performs a series of row interchanges on the matrix A. + One row interchange is initiated for each of rows K1 through K2 of A. + + Arguments + ========= + + N (input) INTEGER + The number of columns of the matrix A. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the matrix of column dimension N to which the row + interchanges will be applied. + On exit, the permuted matrix. + + LDA (input) INTEGER + The leading dimension of the array A. + + K1 (input) INTEGER + The first element of IPIV for which a row interchange will + be done. + + K2 (input) INTEGER + The last element of IPIV for which a row interchange will + be done. + + IPIV (input) INTEGER array, dimension (M*abs(INCX)) + The vector of pivot indices. Only the elements in positions + K1 through K2 of IPIV are accessed. + IPIV(K) = L implies rows K and L are to be interchanged. + + INCX (input) INTEGER + The increment between successive values of IPIV. If IPIV + is negative, the pivots are applied in reverse order. + + Further Details + =============== + + Modified by + R. C. Whaley, Computer Science Dept., Univ. of Tenn., Knoxville, USA + + ===================================================================== + + + Interchange row I with row IPIV(I) for each of rows K1 through K2. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --ipiv; + + /* Function Body */ + if (*incx > 0) { + ix0 = *k1; + i1 = *k1; + i2 = *k2; + inc = 1; + } else if (*incx < 0) { + ix0 = (1 - *k2) * *incx + 1; + i1 = *k2; + i2 = *k1; + inc = -1; + } else { + return 0; + } + + n32 = *n / 32 << 5; + if (n32 != 0) { + i__1 = n32; + for (j = 1; j <= i__1; j += 32) { + ix = ix0; + i__2 = i2; + i__3 = inc; + for (i__ = i1; i__3 < 0 ? i__ >= i__2 : i__ <= i__2; i__ += i__3) + { + ip = ipiv[ix]; + if (ip != i__) { + i__4 = j + 31; + for (k = j; k <= i__4; ++k) { + temp = a[i__ + k * a_dim1]; + a[i__ + k * a_dim1] = a[ip + k * a_dim1]; + a[ip + k * a_dim1] = temp; +/* L10: */ + } + } + ix += *incx; +/* L20: */ + } +/* L30: */ + } + } + if (n32 != *n) { + ++n32; + ix = ix0; + i__1 = i2; + i__3 = inc; + for (i__ = i1; i__3 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__3) { + ip = ipiv[ix]; + if (ip != i__) { + i__2 = *n; + for (k = n32; k <= i__2; ++k) { + temp = a[i__ + k * a_dim1]; + a[i__ + k * a_dim1] = a[ip + k * a_dim1]; + a[ip + k * a_dim1] = temp; +/* L40: */ + } + } + ix += *incx; +/* L50: */ + } + } + + return 0; + +/* End of SLASWP */ + +} /* slaswp_ */ + +/* Subroutine */ int slatrd_(char *uplo, integer *n, integer *nb, real *a, + integer *lda, real *e, real *tau, real *w, integer *ldw) +{ + /* System generated locals */ + integer a_dim1, a_offset, w_dim1, w_offset, i__1, i__2, i__3; + + /* Local variables */ + static integer i__, iw; + extern doublereal sdot_(integer *, real *, integer *, real *, integer *); + static real alpha; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *), + sgemv_(char *, integer *, integer *, real *, real *, integer *, + real *, integer *, real *, real *, integer *), saxpy_( + integer *, real *, real *, integer *, real *, integer *), ssymv_( + char *, integer *, real *, real *, integer *, real *, integer *, + real *, real *, integer *), slarfg_(integer *, real *, + real *, integer *, real *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SLATRD reduces NB rows and columns of a real symmetric matrix A to + symmetric tridiagonal form by an orthogonal similarity + transformation Q' * A * Q, and returns the matrices V and W which are + needed to apply the transformation to the unreduced part of A. + + If UPLO = 'U', SLATRD reduces the last NB rows and columns of a + matrix, of which the upper triangle is supplied; + if UPLO = 'L', SLATRD reduces the first NB rows and columns of a + matrix, of which the lower triangle is supplied. + + This is an auxiliary routine called by SSYTRD. + + Arguments + ========= + + UPLO (input) CHARACTER + Specifies whether the upper or lower triangular part of the + symmetric matrix A is stored: + = 'U': Upper triangular + = 'L': Lower triangular + + N (input) INTEGER + The order of the matrix A. + + NB (input) INTEGER + The number of rows and columns to be reduced. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the symmetric matrix A. If UPLO = 'U', the leading + n-by-n upper triangular part of A contains the upper + triangular part of the matrix A, and the strictly lower + triangular part of A is not referenced. If UPLO = 'L', the + leading n-by-n lower triangular part of A contains the lower + triangular part of the matrix A, and the strictly upper + triangular part of A is not referenced. + On exit: + if UPLO = 'U', the last NB columns have been reduced to + tridiagonal form, with the diagonal elements overwriting + the diagonal elements of A; the elements above the diagonal + with the array TAU, represent the orthogonal matrix Q as a + product of elementary reflectors; + if UPLO = 'L', the first NB columns have been reduced to + tridiagonal form, with the diagonal elements overwriting + the diagonal elements of A; the elements below the diagonal + with the array TAU, represent the orthogonal matrix Q as a + product of elementary reflectors. + See Further Details. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= (1,N). + + E (output) REAL array, dimension (N-1) + If UPLO = 'U', E(n-nb:n-1) contains the superdiagonal + elements of the last NB columns of the reduced matrix; + if UPLO = 'L', E(1:nb) contains the subdiagonal elements of + the first NB columns of the reduced matrix. + + TAU (output) REAL array, dimension (N-1) + The scalar factors of the elementary reflectors, stored in + TAU(n-nb:n-1) if UPLO = 'U', and in TAU(1:nb) if UPLO = 'L'. + See Further Details. + + W (output) REAL array, dimension (LDW,NB) + The n-by-nb matrix W required to update the unreduced part + of A. + + LDW (input) INTEGER + The leading dimension of the array W. LDW >= max(1,N). + + Further Details + =============== + + If UPLO = 'U', the matrix Q is represented as a product of elementary + reflectors + + Q = H(n) H(n-1) . . . H(n-nb+1). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(i:n) = 0 and v(i-1) = 1; v(1:i-1) is stored on exit in A(1:i-1,i), + and tau in TAU(i-1). + + If UPLO = 'L', the matrix Q is represented as a product of elementary + reflectors + + Q = H(1) H(2) . . . H(nb). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(1:i) = 0 and v(i+1) = 1; v(i+1:n) is stored on exit in A(i+1:n,i), + and tau in TAU(i). + + The elements of the vectors v together form the n-by-nb matrix V + which is needed, with W, to apply the transformation to the unreduced + part of the matrix, using a symmetric rank-2k update of the form: + A := A - V*W' - W*V'. + + The contents of A on exit are illustrated by the following examples + with n = 5 and nb = 2: + + if UPLO = 'U': if UPLO = 'L': + + ( a a a v4 v5 ) ( d ) + ( a a v4 v5 ) ( 1 d ) + ( a 1 v5 ) ( v1 1 a ) + ( d 1 ) ( v1 v2 a a ) + ( d ) ( v1 v2 a a a ) + + where d denotes a diagonal element of the reduced matrix, a denotes + an element of the original matrix that is unchanged, and vi denotes + an element of the vector defining H(i). + + ===================================================================== + + + Quick return if possible +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --e; + --tau; + w_dim1 = *ldw; + w_offset = 1 + w_dim1; + w -= w_offset; + + /* Function Body */ + if (*n <= 0) { + return 0; + } + + if (lsame_(uplo, "U")) { + +/* Reduce last NB columns of upper triangle */ + + i__1 = *n - *nb + 1; + for (i__ = *n; i__ >= i__1; --i__) { + iw = i__ - *n + *nb; + if (i__ < *n) { + +/* Update A(1:i,i) */ + + i__2 = *n - i__; + sgemv_("No transpose", &i__, &i__2, &c_b151, &a[(i__ + 1) * + a_dim1 + 1], lda, &w[i__ + (iw + 1) * w_dim1], ldw, & + c_b15, &a[i__ * a_dim1 + 1], &c__1); + i__2 = *n - i__; + sgemv_("No transpose", &i__, &i__2, &c_b151, &w[(iw + 1) * + w_dim1 + 1], ldw, &a[i__ + (i__ + 1) * a_dim1], lda, & + c_b15, &a[i__ * a_dim1 + 1], &c__1); + } + if (i__ > 1) { + +/* + Generate elementary reflector H(i) to annihilate + A(1:i-2,i) +*/ + + i__2 = i__ - 1; + slarfg_(&i__2, &a[i__ - 1 + i__ * a_dim1], &a[i__ * a_dim1 + + 1], &c__1, &tau[i__ - 1]); + e[i__ - 1] = a[i__ - 1 + i__ * a_dim1]; + a[i__ - 1 + i__ * a_dim1] = 1.f; + +/* Compute W(1:i-1,i) */ + + i__2 = i__ - 1; + ssymv_("Upper", &i__2, &c_b15, &a[a_offset], lda, &a[i__ * + a_dim1 + 1], &c__1, &c_b29, &w[iw * w_dim1 + 1], & + c__1); + if (i__ < *n) { + i__2 = i__ - 1; + i__3 = *n - i__; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &w[(iw + 1) * + w_dim1 + 1], ldw, &a[i__ * a_dim1 + 1], &c__1, & + c_b29, &w[i__ + 1 + iw * w_dim1], &c__1); + i__2 = i__ - 1; + i__3 = *n - i__; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &a[(i__ + 1) + * a_dim1 + 1], lda, &w[i__ + 1 + iw * w_dim1], & + c__1, &c_b15, &w[iw * w_dim1 + 1], &c__1); + i__2 = i__ - 1; + i__3 = *n - i__; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &a[(i__ + 1) * + a_dim1 + 1], lda, &a[i__ * a_dim1 + 1], &c__1, & + c_b29, &w[i__ + 1 + iw * w_dim1], &c__1); + i__2 = i__ - 1; + i__3 = *n - i__; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &w[(iw + 1) + * w_dim1 + 1], ldw, &w[i__ + 1 + iw * w_dim1], & + c__1, &c_b15, &w[iw * w_dim1 + 1], &c__1); + } + i__2 = i__ - 1; + sscal_(&i__2, &tau[i__ - 1], &w[iw * w_dim1 + 1], &c__1); + i__2 = i__ - 1; + alpha = tau[i__ - 1] * -.5f * sdot_(&i__2, &w[iw * w_dim1 + 1] + , &c__1, &a[i__ * a_dim1 + 1], &c__1); + i__2 = i__ - 1; + saxpy_(&i__2, &alpha, &a[i__ * a_dim1 + 1], &c__1, &w[iw * + w_dim1 + 1], &c__1); + } + +/* L10: */ + } + } else { + +/* Reduce first NB columns of lower triangle */ + + i__1 = *nb; + for (i__ = 1; i__ <= i__1; ++i__) { + +/* Update A(i:n,i) */ + + i__2 = *n - i__ + 1; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &a[i__ + a_dim1], + lda, &w[i__ + w_dim1], ldw, &c_b15, &a[i__ + i__ * a_dim1] + , &c__1); + i__2 = *n - i__ + 1; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &w[i__ + w_dim1], + ldw, &a[i__ + a_dim1], lda, &c_b15, &a[i__ + i__ * a_dim1] + , &c__1); + if (i__ < *n) { + +/* + Generate elementary reflector H(i) to annihilate + A(i+2:n,i) +*/ + + i__2 = *n - i__; +/* Computing MIN */ + i__3 = i__ + 2; + slarfg_(&i__2, &a[i__ + 1 + i__ * a_dim1], &a[min(i__3,*n) + + i__ * a_dim1], &c__1, &tau[i__]); + e[i__] = a[i__ + 1 + i__ * a_dim1]; + a[i__ + 1 + i__ * a_dim1] = 1.f; + +/* Compute W(i+1:n,i) */ + + i__2 = *n - i__; + ssymv_("Lower", &i__2, &c_b15, &a[i__ + 1 + (i__ + 1) * + a_dim1], lda, &a[i__ + 1 + i__ * a_dim1], &c__1, & + c_b29, &w[i__ + 1 + i__ * w_dim1], &c__1); + i__2 = *n - i__; + i__3 = i__ - 1; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &w[i__ + 1 + w_dim1] + , ldw, &a[i__ + 1 + i__ * a_dim1], &c__1, &c_b29, &w[ + i__ * w_dim1 + 1], &c__1); + i__2 = *n - i__; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &a[i__ + 1 + + a_dim1], lda, &w[i__ * w_dim1 + 1], &c__1, &c_b15, &w[ + i__ + 1 + i__ * w_dim1], &c__1); + i__2 = *n - i__; + i__3 = i__ - 1; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &a[i__ + 1 + a_dim1] + , lda, &a[i__ + 1 + i__ * a_dim1], &c__1, &c_b29, &w[ + i__ * w_dim1 + 1], &c__1); + i__2 = *n - i__; + i__3 = i__ - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &w[i__ + 1 + + w_dim1], ldw, &w[i__ * w_dim1 + 1], &c__1, &c_b15, &w[ + i__ + 1 + i__ * w_dim1], &c__1); + i__2 = *n - i__; + sscal_(&i__2, &tau[i__], &w[i__ + 1 + i__ * w_dim1], &c__1); + i__2 = *n - i__; + alpha = tau[i__] * -.5f * sdot_(&i__2, &w[i__ + 1 + i__ * + w_dim1], &c__1, &a[i__ + 1 + i__ * a_dim1], &c__1); + i__2 = *n - i__; + saxpy_(&i__2, &alpha, &a[i__ + 1 + i__ * a_dim1], &c__1, &w[ + i__ + 1 + i__ * w_dim1], &c__1); + } + +/* L20: */ + } + } + + return 0; + +/* End of SLATRD */ + +} /* slatrd_ */ + +/* Subroutine */ int slauu2_(char *uplo, integer *n, real *a, integer *lda, + integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + + /* Local variables */ + static integer i__; + static real aii; + extern doublereal sdot_(integer *, real *, integer *, real *, integer *); + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *), + sgemv_(char *, integer *, integer *, real *, real *, integer *, + real *, integer *, real *, real *, integer *); + static logical upper; + extern /* Subroutine */ int xerbla_(char *, integer *); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SLAUU2 computes the product U * U' or L' * L, where the triangular + factor U or L is stored in the upper or lower triangular part of + the array A. + + If UPLO = 'U' or 'u' then the upper triangle of the result is stored, + overwriting the factor U in A. + If UPLO = 'L' or 'l' then the lower triangle of the result is stored, + overwriting the factor L in A. + + This is the unblocked form of the algorithm, calling Level 2 BLAS. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + Specifies whether the triangular factor stored in the array A + is upper or lower triangular: + = 'U': Upper triangular + = 'L': Lower triangular + + N (input) INTEGER + The order of the triangular factor U or L. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the triangular factor U or L. + On exit, if UPLO = 'U', the upper triangle of A is + overwritten with the upper triangle of the product U * U'; + if UPLO = 'L', the lower triangle of A is overwritten with + the lower triangle of the product L' * L. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -k, the k-th argument had an illegal value + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + + /* Function Body */ + *info = 0; + upper = lsame_(uplo, "U"); + if (! upper && ! lsame_(uplo, "L")) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*n)) { + *info = -4; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLAUU2", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + + if (upper) { + +/* Compute the product U * U'. */ + + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + aii = a[i__ + i__ * a_dim1]; + if (i__ < *n) { + i__2 = *n - i__ + 1; + a[i__ + i__ * a_dim1] = sdot_(&i__2, &a[i__ + i__ * a_dim1], + lda, &a[i__ + i__ * a_dim1], lda); + i__2 = i__ - 1; + i__3 = *n - i__; + sgemv_("No transpose", &i__2, &i__3, &c_b15, &a[(i__ + 1) * + a_dim1 + 1], lda, &a[i__ + (i__ + 1) * a_dim1], lda, & + aii, &a[i__ * a_dim1 + 1], &c__1); + } else { + sscal_(&i__, &aii, &a[i__ * a_dim1 + 1], &c__1); + } +/* L10: */ + } + + } else { + +/* Compute the product L' * L. */ + + i__1 = *n; + for (i__ = 1; i__ <= i__1; ++i__) { + aii = a[i__ + i__ * a_dim1]; + if (i__ < *n) { + i__2 = *n - i__ + 1; + a[i__ + i__ * a_dim1] = sdot_(&i__2, &a[i__ + i__ * a_dim1], & + c__1, &a[i__ + i__ * a_dim1], &c__1); + i__2 = *n - i__; + i__3 = i__ - 1; + sgemv_("Transpose", &i__2, &i__3, &c_b15, &a[i__ + 1 + a_dim1] + , lda, &a[i__ + 1 + i__ * a_dim1], &c__1, &aii, &a[ + i__ + a_dim1], lda); + } else { + sscal_(&i__, &aii, &a[i__ + a_dim1], lda); + } +/* L20: */ + } + } + + return 0; + +/* End of SLAUU2 */ + +} /* slauu2_ */ + +/* Subroutine */ int slauum_(char *uplo, integer *n, real *a, integer *lda, + integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3, i__4; + + /* Local variables */ + static integer i__, ib, nb; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *); + static logical upper; + extern /* Subroutine */ int strmm_(char *, char *, char *, char *, + integer *, integer *, real *, real *, integer *, real *, integer * + ), ssyrk_(char *, char *, integer + *, integer *, real *, real *, integer *, real *, real *, integer * + ), slauu2_(char *, integer *, real *, integer *, + integer *), xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + + +/* + -- LAPACK auxiliary routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SLAUUM computes the product U * U' or L' * L, where the triangular + factor U or L is stored in the upper or lower triangular part of + the array A. + + If UPLO = 'U' or 'u' then the upper triangle of the result is stored, + overwriting the factor U in A. + If UPLO = 'L' or 'l' then the lower triangle of the result is stored, + overwriting the factor L in A. + + This is the blocked form of the algorithm, calling Level 3 BLAS. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + Specifies whether the triangular factor stored in the array A + is upper or lower triangular: + = 'U': Upper triangular + = 'L': Lower triangular + + N (input) INTEGER + The order of the triangular factor U or L. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the triangular factor U or L. + On exit, if UPLO = 'U', the upper triangle of A is + overwritten with the upper triangle of the product U * U'; + if UPLO = 'L', the lower triangle of A is overwritten with + the lower triangle of the product L' * L. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -k, the k-th argument had an illegal value + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + + /* Function Body */ + *info = 0; + upper = lsame_(uplo, "U"); + if (! upper && ! lsame_(uplo, "L")) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*n)) { + *info = -4; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SLAUUM", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + +/* Determine the block size for this environment. */ + + nb = ilaenv_(&c__1, "SLAUUM", uplo, n, &c_n1, &c_n1, &c_n1, (ftnlen)6, ( + ftnlen)1); + + if (nb <= 1 || nb >= *n) { + +/* Use unblocked code */ + + slauu2_(uplo, n, &a[a_offset], lda, info); + } else { + +/* Use blocked code */ + + if (upper) { + +/* Compute the product U * U'. */ + + i__1 = *n; + i__2 = nb; + for (i__ = 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { +/* Computing MIN */ + i__3 = nb, i__4 = *n - i__ + 1; + ib = min(i__3,i__4); + i__3 = i__ - 1; + strmm_("Right", "Upper", "Transpose", "Non-unit", &i__3, &ib, + &c_b15, &a[i__ + i__ * a_dim1], lda, &a[i__ * a_dim1 + + 1], lda) + ; + slauu2_("Upper", &ib, &a[i__ + i__ * a_dim1], lda, info); + if (i__ + ib <= *n) { + i__3 = i__ - 1; + i__4 = *n - i__ - ib + 1; + sgemm_("No transpose", "Transpose", &i__3, &ib, &i__4, & + c_b15, &a[(i__ + ib) * a_dim1 + 1], lda, &a[i__ + + (i__ + ib) * a_dim1], lda, &c_b15, &a[i__ * + a_dim1 + 1], lda); + i__3 = *n - i__ - ib + 1; + ssyrk_("Upper", "No transpose", &ib, &i__3, &c_b15, &a[ + i__ + (i__ + ib) * a_dim1], lda, &c_b15, &a[i__ + + i__ * a_dim1], lda); + } +/* L10: */ + } + } else { + +/* Compute the product L' * L. */ + + i__2 = *n; + i__1 = nb; + for (i__ = 1; i__1 < 0 ? i__ >= i__2 : i__ <= i__2; i__ += i__1) { +/* Computing MIN */ + i__3 = nb, i__4 = *n - i__ + 1; + ib = min(i__3,i__4); + i__3 = i__ - 1; + strmm_("Left", "Lower", "Transpose", "Non-unit", &ib, &i__3, & + c_b15, &a[i__ + i__ * a_dim1], lda, &a[i__ + a_dim1], + lda); + slauu2_("Lower", &ib, &a[i__ + i__ * a_dim1], lda, info); + if (i__ + ib <= *n) { + i__3 = i__ - 1; + i__4 = *n - i__ - ib + 1; + sgemm_("Transpose", "No transpose", &ib, &i__3, &i__4, & + c_b15, &a[i__ + ib + i__ * a_dim1], lda, &a[i__ + + ib + a_dim1], lda, &c_b15, &a[i__ + a_dim1], lda); + i__3 = *n - i__ - ib + 1; + ssyrk_("Lower", "Transpose", &ib, &i__3, &c_b15, &a[i__ + + ib + i__ * a_dim1], lda, &c_b15, &a[i__ + i__ * + a_dim1], lda); + } +/* L20: */ + } + } + } + + return 0; + +/* End of SLAUUM */ + +} /* slauum_ */ + +/* Subroutine */ int sorg2r_(integer *m, integer *n, integer *k, real *a, + integer *lda, real *tau, real *work, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2; + real r__1; + + /* Local variables */ + static integer i__, j, l; + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *), + slarf_(char *, integer *, integer *, real *, integer *, real *, + real *, integer *, real *), xerbla_(char *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SORG2R generates an m by n real matrix Q with orthonormal columns, + which is defined as the first n columns of a product of k elementary + reflectors of order m + + Q = H(1) H(2) . . . H(k) + + as returned by SGEQRF. + + Arguments + ========= + + M (input) INTEGER + The number of rows of the matrix Q. M >= 0. + + N (input) INTEGER + The number of columns of the matrix Q. M >= N >= 0. + + K (input) INTEGER + The number of elementary reflectors whose product defines the + matrix Q. N >= K >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the i-th column must contain the vector which + defines the elementary reflector H(i), for i = 1,2,...,k, as + returned by SGEQRF in the first k columns of its array + argument A. + On exit, the m-by-n matrix Q. + + LDA (input) INTEGER + The first dimension of the array A. LDA >= max(1,M). + + TAU (input) REAL array, dimension (K) + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SGEQRF. + + WORK (workspace) REAL array, dimension (N) + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument has an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; + if (*m < 0) { + *info = -1; + } else if (*n < 0 || *n > *m) { + *info = -2; + } else if (*k < 0 || *k > *n) { + *info = -3; + } else if (*lda < max(1,*m)) { + *info = -5; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORG2R", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n <= 0) { + return 0; + } + +/* Initialise columns k+1:n to columns of the unit matrix */ + + i__1 = *n; + for (j = *k + 1; j <= i__1; ++j) { + i__2 = *m; + for (l = 1; l <= i__2; ++l) { + a[l + j * a_dim1] = 0.f; +/* L10: */ + } + a[j + j * a_dim1] = 1.f; +/* L20: */ + } + + for (i__ = *k; i__ >= 1; --i__) { + +/* Apply H(i) to A(i:m,i:n) from the left */ + + if (i__ < *n) { + a[i__ + i__ * a_dim1] = 1.f; + i__1 = *m - i__ + 1; + i__2 = *n - i__; + slarf_("Left", &i__1, &i__2, &a[i__ + i__ * a_dim1], &c__1, &tau[ + i__], &a[i__ + (i__ + 1) * a_dim1], lda, &work[1]); + } + if (i__ < *m) { + i__1 = *m - i__; + r__1 = -tau[i__]; + sscal_(&i__1, &r__1, &a[i__ + 1 + i__ * a_dim1], &c__1); + } + a[i__ + i__ * a_dim1] = 1.f - tau[i__]; + +/* Set A(1:i-1,i) to zero */ + + i__1 = i__ - 1; + for (l = 1; l <= i__1; ++l) { + a[l + i__ * a_dim1] = 0.f; +/* L30: */ + } +/* L40: */ + } + return 0; + +/* End of SORG2R */ + +} /* sorg2r_ */ + +/* Subroutine */ int sorgbr_(char *vect, integer *m, integer *n, integer *k, + real *a, integer *lda, real *tau, real *work, integer *lwork, integer + *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + + /* Local variables */ + static integer i__, j, nb, mn; + extern logical lsame_(char *, char *); + static integer iinfo; + static logical wantq; + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int sorglq_(integer *, integer *, integer *, real + *, integer *, real *, real *, integer *, integer *), sorgqr_( + integer *, integer *, integer *, real *, integer *, real *, real * + , integer *, integer *); + static integer lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SORGBR generates one of the real orthogonal matrices Q or P**T + determined by SGEBRD when reducing a real matrix A to bidiagonal + form: A = Q * B * P**T. Q and P**T are defined as products of + elementary reflectors H(i) or G(i) respectively. + + If VECT = 'Q', A is assumed to have been an M-by-K matrix, and Q + is of order M: + if m >= k, Q = H(1) H(2) . . . H(k) and SORGBR returns the first n + columns of Q, where m >= n >= k; + if m < k, Q = H(1) H(2) . . . H(m-1) and SORGBR returns Q as an + M-by-M matrix. + + If VECT = 'P', A is assumed to have been a K-by-N matrix, and P**T + is of order N: + if k < n, P**T = G(k) . . . G(2) G(1) and SORGBR returns the first m + rows of P**T, where n >= m >= k; + if k >= n, P**T = G(n-1) . . . G(2) G(1) and SORGBR returns P**T as + an N-by-N matrix. + + Arguments + ========= + + VECT (input) CHARACTER*1 + Specifies whether the matrix Q or the matrix P**T is + required, as defined in the transformation applied by SGEBRD: + = 'Q': generate Q; + = 'P': generate P**T. + + M (input) INTEGER + The number of rows of the matrix Q or P**T to be returned. + M >= 0. + + N (input) INTEGER + The number of columns of the matrix Q or P**T to be returned. + N >= 0. + If VECT = 'Q', M >= N >= min(M,K); + if VECT = 'P', N >= M >= min(N,K). + + K (input) INTEGER + If VECT = 'Q', the number of columns in the original M-by-K + matrix reduced by SGEBRD. + If VECT = 'P', the number of rows in the original K-by-N + matrix reduced by SGEBRD. + K >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the vectors which define the elementary reflectors, + as returned by SGEBRD. + On exit, the M-by-N matrix Q or P**T. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,M). + + TAU (input) REAL array, dimension + (min(M,K)) if VECT = 'Q' + (min(N,K)) if VECT = 'P' + TAU(i) must contain the scalar factor of the elementary + reflector H(i) or G(i), which determines Q or P**T, as + returned by SGEBRD in its array argument TAUQ or TAUP. + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. LWORK >= max(1,min(M,N)). + For optimum performance LWORK >= min(M,N)*NB, where NB + is the optimal blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; + wantq = lsame_(vect, "Q"); + mn = min(*m,*n); + lquery = *lwork == -1; + if (! wantq && ! lsame_(vect, "P")) { + *info = -1; + } else if (*m < 0) { + *info = -2; + } else if (*n < 0 || wantq && (*n > *m || *n < min(*m,*k)) || ! wantq && ( + *m > *n || *m < min(*n,*k))) { + *info = -3; + } else if (*k < 0) { + *info = -4; + } else if (*lda < max(1,*m)) { + *info = -6; + } else if (*lwork < max(1,mn) && ! lquery) { + *info = -9; + } + + if (*info == 0) { + if (wantq) { + nb = ilaenv_(&c__1, "SORGQR", " ", m, n, k, &c_n1, (ftnlen)6, ( + ftnlen)1); + } else { + nb = ilaenv_(&c__1, "SORGLQ", " ", m, n, k, &c_n1, (ftnlen)6, ( + ftnlen)1); + } + lwkopt = max(1,mn) * nb; + work[1] = (real) lwkopt; + } + + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORGBR", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0) { + work[1] = 1.f; + return 0; + } + + if (wantq) { + +/* + Form Q, determined by a call to SGEBRD to reduce an m-by-k + matrix +*/ + + if (*m >= *k) { + +/* If m >= k, assume m >= n >= k */ + + sorgqr_(m, n, k, &a[a_offset], lda, &tau[1], &work[1], lwork, & + iinfo); + + } else { + +/* + If m < k, assume m = n + + Shift the vectors which define the elementary reflectors one + column to the right, and set the first row and column of Q + to those of the unit matrix +*/ + + for (j = *m; j >= 2; --j) { + a[j * a_dim1 + 1] = 0.f; + i__1 = *m; + for (i__ = j + 1; i__ <= i__1; ++i__) { + a[i__ + j * a_dim1] = a[i__ + (j - 1) * a_dim1]; +/* L10: */ + } +/* L20: */ + } + a[a_dim1 + 1] = 1.f; + i__1 = *m; + for (i__ = 2; i__ <= i__1; ++i__) { + a[i__ + a_dim1] = 0.f; +/* L30: */ + } + if (*m > 1) { + +/* Form Q(2:m,2:m) */ + + i__1 = *m - 1; + i__2 = *m - 1; + i__3 = *m - 1; + sorgqr_(&i__1, &i__2, &i__3, &a[(a_dim1 << 1) + 2], lda, &tau[ + 1], &work[1], lwork, &iinfo); + } + } + } else { + +/* + Form P', determined by a call to SGEBRD to reduce a k-by-n + matrix +*/ + + if (*k < *n) { + +/* If k < n, assume k <= m <= n */ + + sorglq_(m, n, k, &a[a_offset], lda, &tau[1], &work[1], lwork, & + iinfo); + + } else { + +/* + If k >= n, assume m = n + + Shift the vectors which define the elementary reflectors one + row downward, and set the first row and column of P' to + those of the unit matrix +*/ + + a[a_dim1 + 1] = 1.f; + i__1 = *n; + for (i__ = 2; i__ <= i__1; ++i__) { + a[i__ + a_dim1] = 0.f; +/* L40: */ + } + i__1 = *n; + for (j = 2; j <= i__1; ++j) { + for (i__ = j - 1; i__ >= 2; --i__) { + a[i__ + j * a_dim1] = a[i__ - 1 + j * a_dim1]; +/* L50: */ + } + a[j * a_dim1 + 1] = 0.f; +/* L60: */ + } + if (*n > 1) { + +/* Form P'(2:n,2:n) */ + + i__1 = *n - 1; + i__2 = *n - 1; + i__3 = *n - 1; + sorglq_(&i__1, &i__2, &i__3, &a[(a_dim1 << 1) + 2], lda, &tau[ + 1], &work[1], lwork, &iinfo); + } + } + } + work[1] = (real) lwkopt; + return 0; + +/* End of SORGBR */ + +} /* sorgbr_ */ + +/* Subroutine */ int sorghr_(integer *n, integer *ilo, integer *ihi, real *a, + integer *lda, real *tau, real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2; + + /* Local variables */ + static integer i__, j, nb, nh, iinfo; + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int sorgqr_(integer *, integer *, integer *, real + *, integer *, real *, real *, integer *, integer *); + static integer lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SORGHR generates a real orthogonal matrix Q which is defined as the + product of IHI-ILO elementary reflectors of order N, as returned by + SGEHRD: + + Q = H(ilo) H(ilo+1) . . . H(ihi-1). + + Arguments + ========= + + N (input) INTEGER + The order of the matrix Q. N >= 0. + + ILO (input) INTEGER + IHI (input) INTEGER + ILO and IHI must have the same values as in the previous call + of SGEHRD. Q is equal to the unit matrix except in the + submatrix Q(ilo+1:ihi,ilo+1:ihi). + 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the vectors which define the elementary reflectors, + as returned by SGEHRD. + On exit, the N-by-N orthogonal matrix Q. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + TAU (input) REAL array, dimension (N-1) + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SGEHRD. + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. LWORK >= IHI-ILO. + For optimum performance LWORK >= (IHI-ILO)*NB, where NB is + the optimal blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; + nh = *ihi - *ilo; + lquery = *lwork == -1; + if (*n < 0) { + *info = -1; + } else if (*ilo < 1 || *ilo > max(1,*n)) { + *info = -2; + } else if (*ihi < min(*ilo,*n) || *ihi > *n) { + *info = -3; + } else if (*lda < max(1,*n)) { + *info = -5; + } else if (*lwork < max(1,nh) && ! lquery) { + *info = -8; + } + + if (*info == 0) { + nb = ilaenv_(&c__1, "SORGQR", " ", &nh, &nh, &nh, &c_n1, (ftnlen)6, ( + ftnlen)1); + lwkopt = max(1,nh) * nb; + work[1] = (real) lwkopt; + } + + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORGHR", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + work[1] = 1.f; + return 0; + } + +/* + Shift the vectors which define the elementary reflectors one + column to the right, and set the first ilo and the last n-ihi + rows and columns to those of the unit matrix +*/ + + i__1 = *ilo + 1; + for (j = *ihi; j >= i__1; --j) { + i__2 = j - 1; + for (i__ = 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] = 0.f; +/* L10: */ + } + i__2 = *ihi; + for (i__ = j + 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] = a[i__ + (j - 1) * a_dim1]; +/* L20: */ + } + i__2 = *n; + for (i__ = *ihi + 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] = 0.f; +/* L30: */ + } +/* L40: */ + } + i__1 = *ilo; + for (j = 1; j <= i__1; ++j) { + i__2 = *n; + for (i__ = 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] = 0.f; +/* L50: */ + } + a[j + j * a_dim1] = 1.f; +/* L60: */ + } + i__1 = *n; + for (j = *ihi + 1; j <= i__1; ++j) { + i__2 = *n; + for (i__ = 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] = 0.f; +/* L70: */ + } + a[j + j * a_dim1] = 1.f; +/* L80: */ + } + + if (nh > 0) { + +/* Generate Q(ilo+1:ihi,ilo+1:ihi) */ + + sorgqr_(&nh, &nh, &nh, &a[*ilo + 1 + (*ilo + 1) * a_dim1], lda, &tau[* + ilo], &work[1], lwork, &iinfo); + } + work[1] = (real) lwkopt; + return 0; + +/* End of SORGHR */ + +} /* sorghr_ */ + +/* Subroutine */ int sorgl2_(integer *m, integer *n, integer *k, real *a, + integer *lda, real *tau, real *work, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2; + real r__1; + + /* Local variables */ + static integer i__, j, l; + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *), + slarf_(char *, integer *, integer *, real *, integer *, real *, + real *, integer *, real *), xerbla_(char *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SORGL2 generates an m by n real matrix Q with orthonormal rows, + which is defined as the first m rows of a product of k elementary + reflectors of order n + + Q = H(k) . . . H(2) H(1) + + as returned by SGELQF. + + Arguments + ========= + + M (input) INTEGER + The number of rows of the matrix Q. M >= 0. + + N (input) INTEGER + The number of columns of the matrix Q. N >= M. + + K (input) INTEGER + The number of elementary reflectors whose product defines the + matrix Q. M >= K >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the i-th row must contain the vector which defines + the elementary reflector H(i), for i = 1,2,...,k, as returned + by SGELQF in the first k rows of its array argument A. + On exit, the m-by-n matrix Q. + + LDA (input) INTEGER + The first dimension of the array A. LDA >= max(1,M). + + TAU (input) REAL array, dimension (K) + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SGELQF. + + WORK (workspace) REAL array, dimension (M) + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument has an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; + if (*m < 0) { + *info = -1; + } else if (*n < *m) { + *info = -2; + } else if (*k < 0 || *k > *m) { + *info = -3; + } else if (*lda < max(1,*m)) { + *info = -5; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORGL2", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*m <= 0) { + return 0; + } + + if (*k < *m) { + +/* Initialise rows k+1:m to rows of the unit matrix */ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (l = *k + 1; l <= i__2; ++l) { + a[l + j * a_dim1] = 0.f; +/* L10: */ + } + if (j > *k && j <= *m) { + a[j + j * a_dim1] = 1.f; + } +/* L20: */ + } + } + + for (i__ = *k; i__ >= 1; --i__) { + +/* Apply H(i) to A(i:m,i:n) from the right */ + + if (i__ < *n) { + if (i__ < *m) { + a[i__ + i__ * a_dim1] = 1.f; + i__1 = *m - i__; + i__2 = *n - i__ + 1; + slarf_("Right", &i__1, &i__2, &a[i__ + i__ * a_dim1], lda, & + tau[i__], &a[i__ + 1 + i__ * a_dim1], lda, &work[1]); + } + i__1 = *n - i__; + r__1 = -tau[i__]; + sscal_(&i__1, &r__1, &a[i__ + (i__ + 1) * a_dim1], lda); + } + a[i__ + i__ * a_dim1] = 1.f - tau[i__]; + +/* Set A(i,1:i-1) to zero */ + + i__1 = i__ - 1; + for (l = 1; l <= i__1; ++l) { + a[i__ + l * a_dim1] = 0.f; +/* L30: */ + } +/* L40: */ + } + return 0; + +/* End of SORGL2 */ + +} /* sorgl2_ */ + +/* Subroutine */ int sorglq_(integer *m, integer *n, integer *k, real *a, + integer *lda, real *tau, real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + + /* Local variables */ + static integer i__, j, l, ib, nb, ki, kk, nx, iws, nbmin, iinfo; + extern /* Subroutine */ int sorgl2_(integer *, integer *, integer *, real + *, integer *, real *, real *, integer *), slarfb_(char *, char *, + char *, char *, integer *, integer *, integer *, real *, integer * + , real *, integer *, real *, integer *, real *, integer *), xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slarft_(char *, char *, integer *, integer *, + real *, integer *, real *, real *, integer *); + static integer ldwork, lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SORGLQ generates an M-by-N real matrix Q with orthonormal rows, + which is defined as the first M rows of a product of K elementary + reflectors of order N + + Q = H(k) . . . H(2) H(1) + + as returned by SGELQF. + + Arguments + ========= + + M (input) INTEGER + The number of rows of the matrix Q. M >= 0. + + N (input) INTEGER + The number of columns of the matrix Q. N >= M. + + K (input) INTEGER + The number of elementary reflectors whose product defines the + matrix Q. M >= K >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the i-th row must contain the vector which defines + the elementary reflector H(i), for i = 1,2,...,k, as returned + by SGELQF in the first k rows of its array argument A. + On exit, the M-by-N matrix Q. + + LDA (input) INTEGER + The first dimension of the array A. LDA >= max(1,M). + + TAU (input) REAL array, dimension (K) + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SGELQF. + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. LWORK >= max(1,M). + For optimum performance LWORK >= M*NB, where NB is + the optimal blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument has an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; + nb = ilaenv_(&c__1, "SORGLQ", " ", m, n, k, &c_n1, (ftnlen)6, (ftnlen)1); + lwkopt = max(1,*m) * nb; + work[1] = (real) lwkopt; + lquery = *lwork == -1; + if (*m < 0) { + *info = -1; + } else if (*n < *m) { + *info = -2; + } else if (*k < 0 || *k > *m) { + *info = -3; + } else if (*lda < max(1,*m)) { + *info = -5; + } else if (*lwork < max(1,*m) && ! lquery) { + *info = -8; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORGLQ", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*m <= 0) { + work[1] = 1.f; + return 0; + } + + nbmin = 2; + nx = 0; + iws = *m; + if (nb > 1 && nb < *k) { + +/* + Determine when to cross over from blocked to unblocked code. + + Computing MAX +*/ + i__1 = 0, i__2 = ilaenv_(&c__3, "SORGLQ", " ", m, n, k, &c_n1, ( + ftnlen)6, (ftnlen)1); + nx = max(i__1,i__2); + if (nx < *k) { + +/* Determine if workspace is large enough for blocked code. */ + + ldwork = *m; + iws = ldwork * nb; + if (*lwork < iws) { + +/* + Not enough workspace to use optimal NB: reduce NB and + determine the minimum value of NB. +*/ + + nb = *lwork / ldwork; +/* Computing MAX */ + i__1 = 2, i__2 = ilaenv_(&c__2, "SORGLQ", " ", m, n, k, &c_n1, + (ftnlen)6, (ftnlen)1); + nbmin = max(i__1,i__2); + } + } + } + + if (nb >= nbmin && nb < *k && nx < *k) { + +/* + Use blocked code after the last block. + The first kk rows are handled by the block method. +*/ + + ki = (*k - nx - 1) / nb * nb; +/* Computing MIN */ + i__1 = *k, i__2 = ki + nb; + kk = min(i__1,i__2); + +/* Set A(kk+1:m,1:kk) to zero. */ + + i__1 = kk; + for (j = 1; j <= i__1; ++j) { + i__2 = *m; + for (i__ = kk + 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] = 0.f; +/* L10: */ + } +/* L20: */ + } + } else { + kk = 0; + } + +/* Use unblocked code for the last or only block. */ + + if (kk < *m) { + i__1 = *m - kk; + i__2 = *n - kk; + i__3 = *k - kk; + sorgl2_(&i__1, &i__2, &i__3, &a[kk + 1 + (kk + 1) * a_dim1], lda, & + tau[kk + 1], &work[1], &iinfo); + } + + if (kk > 0) { + +/* Use blocked code */ + + i__1 = -nb; + for (i__ = ki + 1; i__1 < 0 ? i__ >= 1 : i__ <= 1; i__ += i__1) { +/* Computing MIN */ + i__2 = nb, i__3 = *k - i__ + 1; + ib = min(i__2,i__3); + if (i__ + ib <= *m) { + +/* + Form the triangular factor of the block reflector + H = H(i) H(i+1) . . . H(i+ib-1) +*/ + + i__2 = *n - i__ + 1; + slarft_("Forward", "Rowwise", &i__2, &ib, &a[i__ + i__ * + a_dim1], lda, &tau[i__], &work[1], &ldwork); + +/* Apply H' to A(i+ib:m,i:n) from the right */ + + i__2 = *m - i__ - ib + 1; + i__3 = *n - i__ + 1; + slarfb_("Right", "Transpose", "Forward", "Rowwise", &i__2, & + i__3, &ib, &a[i__ + i__ * a_dim1], lda, &work[1], & + ldwork, &a[i__ + ib + i__ * a_dim1], lda, &work[ib + + 1], &ldwork); + } + +/* Apply H' to columns i:n of current block */ + + i__2 = *n - i__ + 1; + sorgl2_(&ib, &i__2, &ib, &a[i__ + i__ * a_dim1], lda, &tau[i__], & + work[1], &iinfo); + +/* Set columns 1:i-1 of current block to zero */ + + i__2 = i__ - 1; + for (j = 1; j <= i__2; ++j) { + i__3 = i__ + ib - 1; + for (l = i__; l <= i__3; ++l) { + a[l + j * a_dim1] = 0.f; +/* L30: */ + } +/* L40: */ + } +/* L50: */ + } + } + + work[1] = (real) iws; + return 0; + +/* End of SORGLQ */ + +} /* sorglq_ */ + +/* Subroutine */ int sorgqr_(integer *m, integer *n, integer *k, real *a, + integer *lda, real *tau, real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + + /* Local variables */ + static integer i__, j, l, ib, nb, ki, kk, nx, iws, nbmin, iinfo; + extern /* Subroutine */ int sorg2r_(integer *, integer *, integer *, real + *, integer *, real *, real *, integer *), slarfb_(char *, char *, + char *, char *, integer *, integer *, integer *, real *, integer * + , real *, integer *, real *, integer *, real *, integer *), xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slarft_(char *, char *, integer *, integer *, + real *, integer *, real *, real *, integer *); + static integer ldwork, lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SORGQR generates an M-by-N real matrix Q with orthonormal columns, + which is defined as the first N columns of a product of K elementary + reflectors of order M + + Q = H(1) H(2) . . . H(k) + + as returned by SGEQRF. + + Arguments + ========= + + M (input) INTEGER + The number of rows of the matrix Q. M >= 0. + + N (input) INTEGER + The number of columns of the matrix Q. M >= N >= 0. + + K (input) INTEGER + The number of elementary reflectors whose product defines the + matrix Q. N >= K >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the i-th column must contain the vector which + defines the elementary reflector H(i), for i = 1,2,...,k, as + returned by SGEQRF in the first k columns of its array + argument A. + On exit, the M-by-N matrix Q. + + LDA (input) INTEGER + The first dimension of the array A. LDA >= max(1,M). + + TAU (input) REAL array, dimension (K) + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SGEQRF. + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. LWORK >= max(1,N). + For optimum performance LWORK >= N*NB, where NB is the + optimal blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument has an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + --work; + + /* Function Body */ + *info = 0; + nb = ilaenv_(&c__1, "SORGQR", " ", m, n, k, &c_n1, (ftnlen)6, (ftnlen)1); + lwkopt = max(1,*n) * nb; + work[1] = (real) lwkopt; + lquery = *lwork == -1; + if (*m < 0) { + *info = -1; + } else if (*n < 0 || *n > *m) { + *info = -2; + } else if (*k < 0 || *k > *n) { + *info = -3; + } else if (*lda < max(1,*m)) { + *info = -5; + } else if (*lwork < max(1,*n) && ! lquery) { + *info = -8; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORGQR", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*n <= 0) { + work[1] = 1.f; + return 0; + } + + nbmin = 2; + nx = 0; + iws = *n; + if (nb > 1 && nb < *k) { + +/* + Determine when to cross over from blocked to unblocked code. + + Computing MAX +*/ + i__1 = 0, i__2 = ilaenv_(&c__3, "SORGQR", " ", m, n, k, &c_n1, ( + ftnlen)6, (ftnlen)1); + nx = max(i__1,i__2); + if (nx < *k) { + +/* Determine if workspace is large enough for blocked code. */ + + ldwork = *n; + iws = ldwork * nb; + if (*lwork < iws) { + +/* + Not enough workspace to use optimal NB: reduce NB and + determine the minimum value of NB. +*/ + + nb = *lwork / ldwork; +/* Computing MAX */ + i__1 = 2, i__2 = ilaenv_(&c__2, "SORGQR", " ", m, n, k, &c_n1, + (ftnlen)6, (ftnlen)1); + nbmin = max(i__1,i__2); + } + } + } + + if (nb >= nbmin && nb < *k && nx < *k) { + +/* + Use blocked code after the last block. + The first kk columns are handled by the block method. +*/ + + ki = (*k - nx - 1) / nb * nb; +/* Computing MIN */ + i__1 = *k, i__2 = ki + nb; + kk = min(i__1,i__2); + +/* Set A(1:kk,kk+1:n) to zero. */ + + i__1 = *n; + for (j = kk + 1; j <= i__1; ++j) { + i__2 = kk; + for (i__ = 1; i__ <= i__2; ++i__) { + a[i__ + j * a_dim1] = 0.f; +/* L10: */ + } +/* L20: */ + } + } else { + kk = 0; + } + +/* Use unblocked code for the last or only block. */ + + if (kk < *n) { + i__1 = *m - kk; + i__2 = *n - kk; + i__3 = *k - kk; + sorg2r_(&i__1, &i__2, &i__3, &a[kk + 1 + (kk + 1) * a_dim1], lda, & + tau[kk + 1], &work[1], &iinfo); + } + + if (kk > 0) { + +/* Use blocked code */ + + i__1 = -nb; + for (i__ = ki + 1; i__1 < 0 ? i__ >= 1 : i__ <= 1; i__ += i__1) { +/* Computing MIN */ + i__2 = nb, i__3 = *k - i__ + 1; + ib = min(i__2,i__3); + if (i__ + ib <= *n) { + +/* + Form the triangular factor of the block reflector + H = H(i) H(i+1) . . . H(i+ib-1) +*/ + + i__2 = *m - i__ + 1; + slarft_("Forward", "Columnwise", &i__2, &ib, &a[i__ + i__ * + a_dim1], lda, &tau[i__], &work[1], &ldwork); + +/* Apply H to A(i:m,i+ib:n) from the left */ + + i__2 = *m - i__ + 1; + i__3 = *n - i__ - ib + 1; + slarfb_("Left", "No transpose", "Forward", "Columnwise", & + i__2, &i__3, &ib, &a[i__ + i__ * a_dim1], lda, &work[ + 1], &ldwork, &a[i__ + (i__ + ib) * a_dim1], lda, & + work[ib + 1], &ldwork); + } + +/* Apply H to rows i:m of current block */ + + i__2 = *m - i__ + 1; + sorg2r_(&i__2, &ib, &ib, &a[i__ + i__ * a_dim1], lda, &tau[i__], & + work[1], &iinfo); + +/* Set rows 1:i-1 of current block to zero */ + + i__2 = i__ + ib - 1; + for (j = i__; j <= i__2; ++j) { + i__3 = i__ - 1; + for (l = 1; l <= i__3; ++l) { + a[l + j * a_dim1] = 0.f; +/* L30: */ + } +/* L40: */ + } +/* L50: */ + } + } + + work[1] = (real) iws; + return 0; + +/* End of SORGQR */ + +} /* sorgqr_ */ + +/* Subroutine */ int sorm2l_(char *side, char *trans, integer *m, integer *n, + integer *k, real *a, integer *lda, real *tau, real *c__, integer *ldc, + real *work, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, c_dim1, c_offset, i__1, i__2; + + /* Local variables */ + static integer i__, i1, i2, i3, mi, ni, nq; + static real aii; + static logical left; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int slarf_(char *, integer *, integer *, real *, + integer *, real *, real *, integer *, real *), xerbla_( + char *, integer *); + static logical notran; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SORM2L overwrites the general real m by n matrix C with + + Q * C if SIDE = 'L' and TRANS = 'N', or + + Q'* C if SIDE = 'L' and TRANS = 'T', or + + C * Q if SIDE = 'R' and TRANS = 'N', or + + C * Q' if SIDE = 'R' and TRANS = 'T', + + where Q is a real orthogonal matrix defined as the product of k + elementary reflectors + + Q = H(k) . . . H(2) H(1) + + as returned by SGEQLF. Q is of order m if SIDE = 'L' and of order n + if SIDE = 'R'. + + Arguments + ========= + + SIDE (input) CHARACTER*1 + = 'L': apply Q or Q' from the Left + = 'R': apply Q or Q' from the Right + + TRANS (input) CHARACTER*1 + = 'N': apply Q (No transpose) + = 'T': apply Q' (Transpose) + + M (input) INTEGER + The number of rows of the matrix C. M >= 0. + + N (input) INTEGER + The number of columns of the matrix C. N >= 0. + + K (input) INTEGER + The number of elementary reflectors whose product defines + the matrix Q. + If SIDE = 'L', M >= K >= 0; + if SIDE = 'R', N >= K >= 0. + + A (input) REAL array, dimension (LDA,K) + The i-th column must contain the vector which defines the + elementary reflector H(i), for i = 1,2,...,k, as returned by + SGEQLF in the last k columns of its array argument A. + A is modified by the routine but restored on exit. + + LDA (input) INTEGER + The leading dimension of the array A. + If SIDE = 'L', LDA >= max(1,M); + if SIDE = 'R', LDA >= max(1,N). + + TAU (input) REAL array, dimension (K) + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SGEQLF. + + C (input/output) REAL array, dimension (LDC,N) + On entry, the m by n matrix C. + On exit, C is overwritten by Q*C or Q'*C or C*Q' or C*Q. + + LDC (input) INTEGER + The leading dimension of the array C. LDC >= max(1,M). + + WORK (workspace) REAL array, dimension + (N) if SIDE = 'L', + (M) if SIDE = 'R' + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + *info = 0; + left = lsame_(side, "L"); + notran = lsame_(trans, "N"); + +/* NQ is the order of Q */ + + if (left) { + nq = *m; + } else { + nq = *n; + } + if (! left && ! lsame_(side, "R")) { + *info = -1; + } else if (! notran && ! lsame_(trans, "T")) { + *info = -2; + } else if (*m < 0) { + *info = -3; + } else if (*n < 0) { + *info = -4; + } else if (*k < 0 || *k > nq) { + *info = -5; + } else if (*lda < max(1,nq)) { + *info = -7; + } else if (*ldc < max(1,*m)) { + *info = -10; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORM2L", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0 || *k == 0) { + return 0; + } + + if (left && notran || ! left && ! notran) { + i1 = 1; + i2 = *k; + i3 = 1; + } else { + i1 = *k; + i2 = 1; + i3 = -1; + } + + if (left) { + ni = *n; + } else { + mi = *m; + } + + i__1 = i2; + i__2 = i3; + for (i__ = i1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { + if (left) { + +/* H(i) is applied to C(1:m-k+i,1:n) */ + + mi = *m - *k + i__; + } else { + +/* H(i) is applied to C(1:m,1:n-k+i) */ + + ni = *n - *k + i__; + } + +/* Apply H(i) */ + + aii = a[nq - *k + i__ + i__ * a_dim1]; + a[nq - *k + i__ + i__ * a_dim1] = 1.f; + slarf_(side, &mi, &ni, &a[i__ * a_dim1 + 1], &c__1, &tau[i__], &c__[ + c_offset], ldc, &work[1]); + a[nq - *k + i__ + i__ * a_dim1] = aii; +/* L10: */ + } + return 0; + +/* End of SORM2L */ + +} /* sorm2l_ */ + +/* Subroutine */ int sorm2r_(char *side, char *trans, integer *m, integer *n, + integer *k, real *a, integer *lda, real *tau, real *c__, integer *ldc, + real *work, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, c_dim1, c_offset, i__1, i__2; + + /* Local variables */ + static integer i__, i1, i2, i3, ic, jc, mi, ni, nq; + static real aii; + static logical left; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int slarf_(char *, integer *, integer *, real *, + integer *, real *, real *, integer *, real *), xerbla_( + char *, integer *); + static logical notran; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SORM2R overwrites the general real m by n matrix C with + + Q * C if SIDE = 'L' and TRANS = 'N', or + + Q'* C if SIDE = 'L' and TRANS = 'T', or + + C * Q if SIDE = 'R' and TRANS = 'N', or + + C * Q' if SIDE = 'R' and TRANS = 'T', + + where Q is a real orthogonal matrix defined as the product of k + elementary reflectors + + Q = H(1) H(2) . . . H(k) + + as returned by SGEQRF. Q is of order m if SIDE = 'L' and of order n + if SIDE = 'R'. + + Arguments + ========= + + SIDE (input) CHARACTER*1 + = 'L': apply Q or Q' from the Left + = 'R': apply Q or Q' from the Right + + TRANS (input) CHARACTER*1 + = 'N': apply Q (No transpose) + = 'T': apply Q' (Transpose) + + M (input) INTEGER + The number of rows of the matrix C. M >= 0. + + N (input) INTEGER + The number of columns of the matrix C. N >= 0. + + K (input) INTEGER + The number of elementary reflectors whose product defines + the matrix Q. + If SIDE = 'L', M >= K >= 0; + if SIDE = 'R', N >= K >= 0. + + A (input) REAL array, dimension (LDA,K) + The i-th column must contain the vector which defines the + elementary reflector H(i), for i = 1,2,...,k, as returned by + SGEQRF in the first k columns of its array argument A. + A is modified by the routine but restored on exit. + + LDA (input) INTEGER + The leading dimension of the array A. + If SIDE = 'L', LDA >= max(1,M); + if SIDE = 'R', LDA >= max(1,N). + + TAU (input) REAL array, dimension (K) + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SGEQRF. + + C (input/output) REAL array, dimension (LDC,N) + On entry, the m by n matrix C. + On exit, C is overwritten by Q*C or Q'*C or C*Q' or C*Q. + + LDC (input) INTEGER + The leading dimension of the array C. LDC >= max(1,M). + + WORK (workspace) REAL array, dimension + (N) if SIDE = 'L', + (M) if SIDE = 'R' + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + *info = 0; + left = lsame_(side, "L"); + notran = lsame_(trans, "N"); + +/* NQ is the order of Q */ + + if (left) { + nq = *m; + } else { + nq = *n; + } + if (! left && ! lsame_(side, "R")) { + *info = -1; + } else if (! notran && ! lsame_(trans, "T")) { + *info = -2; + } else if (*m < 0) { + *info = -3; + } else if (*n < 0) { + *info = -4; + } else if (*k < 0 || *k > nq) { + *info = -5; + } else if (*lda < max(1,nq)) { + *info = -7; + } else if (*ldc < max(1,*m)) { + *info = -10; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORM2R", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0 || *k == 0) { + return 0; + } + + if (left && ! notran || ! left && notran) { + i1 = 1; + i2 = *k; + i3 = 1; + } else { + i1 = *k; + i2 = 1; + i3 = -1; + } + + if (left) { + ni = *n; + jc = 1; + } else { + mi = *m; + ic = 1; + } + + i__1 = i2; + i__2 = i3; + for (i__ = i1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { + if (left) { + +/* H(i) is applied to C(i:m,1:n) */ + + mi = *m - i__ + 1; + ic = i__; + } else { + +/* H(i) is applied to C(1:m,i:n) */ + + ni = *n - i__ + 1; + jc = i__; + } + +/* Apply H(i) */ + + aii = a[i__ + i__ * a_dim1]; + a[i__ + i__ * a_dim1] = 1.f; + slarf_(side, &mi, &ni, &a[i__ + i__ * a_dim1], &c__1, &tau[i__], &c__[ + ic + jc * c_dim1], ldc, &work[1]); + a[i__ + i__ * a_dim1] = aii; +/* L10: */ + } + return 0; + +/* End of SORM2R */ + +} /* sorm2r_ */ + +/* Subroutine */ int sormbr_(char *vect, char *side, char *trans, integer *m, + integer *n, integer *k, real *a, integer *lda, real *tau, real *c__, + integer *ldc, real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + address a__1[2]; + integer a_dim1, a_offset, c_dim1, c_offset, i__1, i__2, i__3[2]; + char ch__1[2]; + + /* Builtin functions */ + /* Subroutine */ int s_cat(char *, char **, integer *, integer *, ftnlen); + + /* Local variables */ + static integer i1, i2, nb, mi, ni, nq, nw; + static logical left; + extern logical lsame_(char *, char *); + static integer iinfo; + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + static logical notran, applyq; + static char transt[1]; + extern /* Subroutine */ int sormlq_(char *, char *, integer *, integer *, + integer *, real *, integer *, real *, real *, integer *, real *, + integer *, integer *); + static integer lwkopt; + static logical lquery; + extern /* Subroutine */ int sormqr_(char *, char *, integer *, integer *, + integer *, real *, integer *, real *, real *, integer *, real *, + integer *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + If VECT = 'Q', SORMBR overwrites the general real M-by-N matrix C + with + SIDE = 'L' SIDE = 'R' + TRANS = 'N': Q * C C * Q + TRANS = 'T': Q**T * C C * Q**T + + If VECT = 'P', SORMBR overwrites the general real M-by-N matrix C + with + SIDE = 'L' SIDE = 'R' + TRANS = 'N': P * C C * P + TRANS = 'T': P**T * C C * P**T + + Here Q and P**T are the orthogonal matrices determined by SGEBRD when + reducing a real matrix A to bidiagonal form: A = Q * B * P**T. Q and + P**T are defined as products of elementary reflectors H(i) and G(i) + respectively. + + Let nq = m if SIDE = 'L' and nq = n if SIDE = 'R'. Thus nq is the + order of the orthogonal matrix Q or P**T that is applied. + + If VECT = 'Q', A is assumed to have been an NQ-by-K matrix: + if nq >= k, Q = H(1) H(2) . . . H(k); + if nq < k, Q = H(1) H(2) . . . H(nq-1). + + If VECT = 'P', A is assumed to have been a K-by-NQ matrix: + if k < nq, P = G(1) G(2) . . . G(k); + if k >= nq, P = G(1) G(2) . . . G(nq-1). + + Arguments + ========= + + VECT (input) CHARACTER*1 + = 'Q': apply Q or Q**T; + = 'P': apply P or P**T. + + SIDE (input) CHARACTER*1 + = 'L': apply Q, Q**T, P or P**T from the Left; + = 'R': apply Q, Q**T, P or P**T from the Right. + + TRANS (input) CHARACTER*1 + = 'N': No transpose, apply Q or P; + = 'T': Transpose, apply Q**T or P**T. + + M (input) INTEGER + The number of rows of the matrix C. M >= 0. + + N (input) INTEGER + The number of columns of the matrix C. N >= 0. + + K (input) INTEGER + If VECT = 'Q', the number of columns in the original + matrix reduced by SGEBRD. + If VECT = 'P', the number of rows in the original + matrix reduced by SGEBRD. + K >= 0. + + A (input) REAL array, dimension + (LDA,min(nq,K)) if VECT = 'Q' + (LDA,nq) if VECT = 'P' + The vectors which define the elementary reflectors H(i) and + G(i), whose products determine the matrices Q and P, as + returned by SGEBRD. + + LDA (input) INTEGER + The leading dimension of the array A. + If VECT = 'Q', LDA >= max(1,nq); + if VECT = 'P', LDA >= max(1,min(nq,K)). + + TAU (input) REAL array, dimension (min(nq,K)) + TAU(i) must contain the scalar factor of the elementary + reflector H(i) or G(i) which determines Q or P, as returned + by SGEBRD in the array argument TAUQ or TAUP. + + C (input/output) REAL array, dimension (LDC,N) + On entry, the M-by-N matrix C. + On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q + or P*C or P**T*C or C*P or C*P**T. + + LDC (input) INTEGER + The leading dimension of the array C. LDC >= max(1,M). + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. + If SIDE = 'L', LWORK >= max(1,N); + if SIDE = 'R', LWORK >= max(1,M). + For optimum performance LWORK >= N*NB if SIDE = 'L', and + LWORK >= M*NB if SIDE = 'R', where NB is the optimal + blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + *info = 0; + applyq = lsame_(vect, "Q"); + left = lsame_(side, "L"); + notran = lsame_(trans, "N"); + lquery = *lwork == -1; + +/* NQ is the order of Q or P and NW is the minimum dimension of WORK */ + + if (left) { + nq = *m; + nw = *n; + } else { + nq = *n; + nw = *m; + } + if (! applyq && ! lsame_(vect, "P")) { + *info = -1; + } else if (! left && ! lsame_(side, "R")) { + *info = -2; + } else if (! notran && ! lsame_(trans, "T")) { + *info = -3; + } else if (*m < 0) { + *info = -4; + } else if (*n < 0) { + *info = -5; + } else if (*k < 0) { + *info = -6; + } else /* if(complicated condition) */ { +/* Computing MAX */ + i__1 = 1, i__2 = min(nq,*k); + if (applyq && *lda < max(1,nq) || ! applyq && *lda < max(i__1,i__2)) { + *info = -8; + } else if (*ldc < max(1,*m)) { + *info = -11; + } else if (*lwork < max(1,nw) && ! lquery) { + *info = -13; + } + } + + if (*info == 0) { + if (applyq) { + if (left) { +/* Writing concatenation */ + i__3[0] = 1, a__1[0] = side; + i__3[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + i__1 = *m - 1; + i__2 = *m - 1; + nb = ilaenv_(&c__1, "SORMQR", ch__1, &i__1, n, &i__2, &c_n1, ( + ftnlen)6, (ftnlen)2); + } else { +/* Writing concatenation */ + i__3[0] = 1, a__1[0] = side; + i__3[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + i__1 = *n - 1; + i__2 = *n - 1; + nb = ilaenv_(&c__1, "SORMQR", ch__1, m, &i__1, &i__2, &c_n1, ( + ftnlen)6, (ftnlen)2); + } + } else { + if (left) { +/* Writing concatenation */ + i__3[0] = 1, a__1[0] = side; + i__3[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + i__1 = *m - 1; + i__2 = *m - 1; + nb = ilaenv_(&c__1, "SORMLQ", ch__1, &i__1, n, &i__2, &c_n1, ( + ftnlen)6, (ftnlen)2); + } else { +/* Writing concatenation */ + i__3[0] = 1, a__1[0] = side; + i__3[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + i__1 = *n - 1; + i__2 = *n - 1; + nb = ilaenv_(&c__1, "SORMLQ", ch__1, m, &i__1, &i__2, &c_n1, ( + ftnlen)6, (ftnlen)2); + } + } + lwkopt = max(1,nw) * nb; + work[1] = (real) lwkopt; + } + + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORMBR", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + work[1] = 1.f; + if (*m == 0 || *n == 0) { + return 0; + } + + if (applyq) { + +/* Apply Q */ + + if (nq >= *k) { + +/* Q was determined by a call to SGEBRD with nq >= k */ + + sormqr_(side, trans, m, n, k, &a[a_offset], lda, &tau[1], &c__[ + c_offset], ldc, &work[1], lwork, &iinfo); + } else if (nq > 1) { + +/* Q was determined by a call to SGEBRD with nq < k */ + + if (left) { + mi = *m - 1; + ni = *n; + i1 = 2; + i2 = 1; + } else { + mi = *m; + ni = *n - 1; + i1 = 1; + i2 = 2; + } + i__1 = nq - 1; + sormqr_(side, trans, &mi, &ni, &i__1, &a[a_dim1 + 2], lda, &tau[1] + , &c__[i1 + i2 * c_dim1], ldc, &work[1], lwork, &iinfo); + } + } else { + +/* Apply P */ + + if (notran) { + *(unsigned char *)transt = 'T'; + } else { + *(unsigned char *)transt = 'N'; + } + if (nq > *k) { + +/* P was determined by a call to SGEBRD with nq > k */ + + sormlq_(side, transt, m, n, k, &a[a_offset], lda, &tau[1], &c__[ + c_offset], ldc, &work[1], lwork, &iinfo); + } else if (nq > 1) { + +/* P was determined by a call to SGEBRD with nq <= k */ + + if (left) { + mi = *m - 1; + ni = *n; + i1 = 2; + i2 = 1; + } else { + mi = *m; + ni = *n - 1; + i1 = 1; + i2 = 2; + } + i__1 = nq - 1; + sormlq_(side, transt, &mi, &ni, &i__1, &a[(a_dim1 << 1) + 1], lda, + &tau[1], &c__[i1 + i2 * c_dim1], ldc, &work[1], lwork, & + iinfo); + } + } + work[1] = (real) lwkopt; + return 0; + +/* End of SORMBR */ + +} /* sormbr_ */ + +/* Subroutine */ int sorml2_(char *side, char *trans, integer *m, integer *n, + integer *k, real *a, integer *lda, real *tau, real *c__, integer *ldc, + real *work, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, c_dim1, c_offset, i__1, i__2; + + /* Local variables */ + static integer i__, i1, i2, i3, ic, jc, mi, ni, nq; + static real aii; + static logical left; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int slarf_(char *, integer *, integer *, real *, + integer *, real *, real *, integer *, real *), xerbla_( + char *, integer *); + static logical notran; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SORML2 overwrites the general real m by n matrix C with + + Q * C if SIDE = 'L' and TRANS = 'N', or + + Q'* C if SIDE = 'L' and TRANS = 'T', or + + C * Q if SIDE = 'R' and TRANS = 'N', or + + C * Q' if SIDE = 'R' and TRANS = 'T', + + where Q is a real orthogonal matrix defined as the product of k + elementary reflectors + + Q = H(k) . . . H(2) H(1) + + as returned by SGELQF. Q is of order m if SIDE = 'L' and of order n + if SIDE = 'R'. + + Arguments + ========= + + SIDE (input) CHARACTER*1 + = 'L': apply Q or Q' from the Left + = 'R': apply Q or Q' from the Right + + TRANS (input) CHARACTER*1 + = 'N': apply Q (No transpose) + = 'T': apply Q' (Transpose) + + M (input) INTEGER + The number of rows of the matrix C. M >= 0. + + N (input) INTEGER + The number of columns of the matrix C. N >= 0. + + K (input) INTEGER + The number of elementary reflectors whose product defines + the matrix Q. + If SIDE = 'L', M >= K >= 0; + if SIDE = 'R', N >= K >= 0. + + A (input) REAL array, dimension + (LDA,M) if SIDE = 'L', + (LDA,N) if SIDE = 'R' + The i-th row must contain the vector which defines the + elementary reflector H(i), for i = 1,2,...,k, as returned by + SGELQF in the first k rows of its array argument A. + A is modified by the routine but restored on exit. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,K). + + TAU (input) REAL array, dimension (K) + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SGELQF. + + C (input/output) REAL array, dimension (LDC,N) + On entry, the m by n matrix C. + On exit, C is overwritten by Q*C or Q'*C or C*Q' or C*Q. + + LDC (input) INTEGER + The leading dimension of the array C. LDC >= max(1,M). + + WORK (workspace) REAL array, dimension + (N) if SIDE = 'L', + (M) if SIDE = 'R' + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + *info = 0; + left = lsame_(side, "L"); + notran = lsame_(trans, "N"); + +/* NQ is the order of Q */ + + if (left) { + nq = *m; + } else { + nq = *n; + } + if (! left && ! lsame_(side, "R")) { + *info = -1; + } else if (! notran && ! lsame_(trans, "T")) { + *info = -2; + } else if (*m < 0) { + *info = -3; + } else if (*n < 0) { + *info = -4; + } else if (*k < 0 || *k > nq) { + *info = -5; + } else if (*lda < max(1,*k)) { + *info = -7; + } else if (*ldc < max(1,*m)) { + *info = -10; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORML2", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0 || *k == 0) { + return 0; + } + + if (left && notran || ! left && ! notran) { + i1 = 1; + i2 = *k; + i3 = 1; + } else { + i1 = *k; + i2 = 1; + i3 = -1; + } + + if (left) { + ni = *n; + jc = 1; + } else { + mi = *m; + ic = 1; + } + + i__1 = i2; + i__2 = i3; + for (i__ = i1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { + if (left) { + +/* H(i) is applied to C(i:m,1:n) */ + + mi = *m - i__ + 1; + ic = i__; + } else { + +/* H(i) is applied to C(1:m,i:n) */ + + ni = *n - i__ + 1; + jc = i__; + } + +/* Apply H(i) */ + + aii = a[i__ + i__ * a_dim1]; + a[i__ + i__ * a_dim1] = 1.f; + slarf_(side, &mi, &ni, &a[i__ + i__ * a_dim1], lda, &tau[i__], &c__[ + ic + jc * c_dim1], ldc, &work[1]); + a[i__ + i__ * a_dim1] = aii; +/* L10: */ + } + return 0; + +/* End of SORML2 */ + +} /* sorml2_ */ + +/* Subroutine */ int sormlq_(char *side, char *trans, integer *m, integer *n, + integer *k, real *a, integer *lda, real *tau, real *c__, integer *ldc, + real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + address a__1[2]; + integer a_dim1, a_offset, c_dim1, c_offset, i__1, i__2, i__3[2], i__4, + i__5; + char ch__1[2]; + + /* Builtin functions */ + /* Subroutine */ int s_cat(char *, char **, integer *, integer *, ftnlen); + + /* Local variables */ + static integer i__; + static real t[4160] /* was [65][64] */; + static integer i1, i2, i3, ib, ic, jc, nb, mi, ni, nq, nw, iws; + static logical left; + extern logical lsame_(char *, char *); + static integer nbmin, iinfo; + extern /* Subroutine */ int sorml2_(char *, char *, integer *, integer *, + integer *, real *, integer *, real *, real *, integer *, real *, + integer *), slarfb_(char *, char *, char *, char * + , integer *, integer *, integer *, real *, integer *, real *, + integer *, real *, integer *, real *, integer *), xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slarft_(char *, char *, integer *, integer *, + real *, integer *, real *, real *, integer *); + static logical notran; + static integer ldwork; + static char transt[1]; + static integer lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SORMLQ overwrites the general real M-by-N matrix C with + + SIDE = 'L' SIDE = 'R' + TRANS = 'N': Q * C C * Q + TRANS = 'T': Q**T * C C * Q**T + + where Q is a real orthogonal matrix defined as the product of k + elementary reflectors + + Q = H(k) . . . H(2) H(1) + + as returned by SGELQF. Q is of order M if SIDE = 'L' and of order N + if SIDE = 'R'. + + Arguments + ========= + + SIDE (input) CHARACTER*1 + = 'L': apply Q or Q**T from the Left; + = 'R': apply Q or Q**T from the Right. + + TRANS (input) CHARACTER*1 + = 'N': No transpose, apply Q; + = 'T': Transpose, apply Q**T. + + M (input) INTEGER + The number of rows of the matrix C. M >= 0. + + N (input) INTEGER + The number of columns of the matrix C. N >= 0. + + K (input) INTEGER + The number of elementary reflectors whose product defines + the matrix Q. + If SIDE = 'L', M >= K >= 0; + if SIDE = 'R', N >= K >= 0. + + A (input) REAL array, dimension + (LDA,M) if SIDE = 'L', + (LDA,N) if SIDE = 'R' + The i-th row must contain the vector which defines the + elementary reflector H(i), for i = 1,2,...,k, as returned by + SGELQF in the first k rows of its array argument A. + A is modified by the routine but restored on exit. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,K). + + TAU (input) REAL array, dimension (K) + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SGELQF. + + C (input/output) REAL array, dimension (LDC,N) + On entry, the M-by-N matrix C. + On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q. + + LDC (input) INTEGER + The leading dimension of the array C. LDC >= max(1,M). + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. + If SIDE = 'L', LWORK >= max(1,N); + if SIDE = 'R', LWORK >= max(1,M). + For optimum performance LWORK >= N*NB if SIDE = 'L', and + LWORK >= M*NB if SIDE = 'R', where NB is the optimal + blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + *info = 0; + left = lsame_(side, "L"); + notran = lsame_(trans, "N"); + lquery = *lwork == -1; + +/* NQ is the order of Q and NW is the minimum dimension of WORK */ + + if (left) { + nq = *m; + nw = *n; + } else { + nq = *n; + nw = *m; + } + if (! left && ! lsame_(side, "R")) { + *info = -1; + } else if (! notran && ! lsame_(trans, "T")) { + *info = -2; + } else if (*m < 0) { + *info = -3; + } else if (*n < 0) { + *info = -4; + } else if (*k < 0 || *k > nq) { + *info = -5; + } else if (*lda < max(1,*k)) { + *info = -7; + } else if (*ldc < max(1,*m)) { + *info = -10; + } else if (*lwork < max(1,nw) && ! lquery) { + *info = -12; + } + + if (*info == 0) { + +/* + Determine the block size. NB may be at most NBMAX, where NBMAX + is used to define the local array T. + + Computing MIN + Writing concatenation +*/ + i__3[0] = 1, a__1[0] = side; + i__3[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + i__1 = 64, i__2 = ilaenv_(&c__1, "SORMLQ", ch__1, m, n, k, &c_n1, ( + ftnlen)6, (ftnlen)2); + nb = min(i__1,i__2); + lwkopt = max(1,nw) * nb; + work[1] = (real) lwkopt; + } + + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORMLQ", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0 || *k == 0) { + work[1] = 1.f; + return 0; + } + + nbmin = 2; + ldwork = nw; + if (nb > 1 && nb < *k) { + iws = nw * nb; + if (*lwork < iws) { + nb = *lwork / ldwork; +/* + Computing MAX + Writing concatenation +*/ + i__3[0] = 1, a__1[0] = side; + i__3[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + i__1 = 2, i__2 = ilaenv_(&c__2, "SORMLQ", ch__1, m, n, k, &c_n1, ( + ftnlen)6, (ftnlen)2); + nbmin = max(i__1,i__2); + } + } else { + iws = nw; + } + + if (nb < nbmin || nb >= *k) { + +/* Use unblocked code */ + + sorml2_(side, trans, m, n, k, &a[a_offset], lda, &tau[1], &c__[ + c_offset], ldc, &work[1], &iinfo); + } else { + +/* Use blocked code */ + + if (left && notran || ! left && ! notran) { + i1 = 1; + i2 = *k; + i3 = nb; + } else { + i1 = (*k - 1) / nb * nb + 1; + i2 = 1; + i3 = -nb; + } + + if (left) { + ni = *n; + jc = 1; + } else { + mi = *m; + ic = 1; + } + + if (notran) { + *(unsigned char *)transt = 'T'; + } else { + *(unsigned char *)transt = 'N'; + } + + i__1 = i2; + i__2 = i3; + for (i__ = i1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { +/* Computing MIN */ + i__4 = nb, i__5 = *k - i__ + 1; + ib = min(i__4,i__5); + +/* + Form the triangular factor of the block reflector + H = H(i) H(i+1) . . . H(i+ib-1) +*/ + + i__4 = nq - i__ + 1; + slarft_("Forward", "Rowwise", &i__4, &ib, &a[i__ + i__ * a_dim1], + lda, &tau[i__], t, &c__65); + if (left) { + +/* H or H' is applied to C(i:m,1:n) */ + + mi = *m - i__ + 1; + ic = i__; + } else { + +/* H or H' is applied to C(1:m,i:n) */ + + ni = *n - i__ + 1; + jc = i__; + } + +/* Apply H or H' */ + + slarfb_(side, transt, "Forward", "Rowwise", &mi, &ni, &ib, &a[i__ + + i__ * a_dim1], lda, t, &c__65, &c__[ic + jc * c_dim1], + ldc, &work[1], &ldwork); +/* L10: */ + } + } + work[1] = (real) lwkopt; + return 0; + +/* End of SORMLQ */ + +} /* sormlq_ */ + +/* Subroutine */ int sormql_(char *side, char *trans, integer *m, integer *n, + integer *k, real *a, integer *lda, real *tau, real *c__, integer *ldc, + real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + address a__1[2]; + integer a_dim1, a_offset, c_dim1, c_offset, i__1, i__2, i__3[2], i__4, + i__5; + char ch__1[2]; + + /* Builtin functions */ + /* Subroutine */ int s_cat(char *, char **, integer *, integer *, ftnlen); + + /* Local variables */ + static integer i__; + static real t[4160] /* was [65][64] */; + static integer i1, i2, i3, ib, nb, mi, ni, nq, nw, iws; + static logical left; + extern logical lsame_(char *, char *); + static integer nbmin, iinfo; + extern /* Subroutine */ int sorm2l_(char *, char *, integer *, integer *, + integer *, real *, integer *, real *, real *, integer *, real *, + integer *), slarfb_(char *, char *, char *, char * + , integer *, integer *, integer *, real *, integer *, real *, + integer *, real *, integer *, real *, integer *), xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slarft_(char *, char *, integer *, integer *, + real *, integer *, real *, real *, integer *); + static logical notran; + static integer ldwork, lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SORMQL overwrites the general real M-by-N matrix C with + + SIDE = 'L' SIDE = 'R' + TRANS = 'N': Q * C C * Q + TRANS = 'T': Q**T * C C * Q**T + + where Q is a real orthogonal matrix defined as the product of k + elementary reflectors + + Q = H(k) . . . H(2) H(1) + + as returned by SGEQLF. Q is of order M if SIDE = 'L' and of order N + if SIDE = 'R'. + + Arguments + ========= + + SIDE (input) CHARACTER*1 + = 'L': apply Q or Q**T from the Left; + = 'R': apply Q or Q**T from the Right. + + TRANS (input) CHARACTER*1 + = 'N': No transpose, apply Q; + = 'T': Transpose, apply Q**T. + + M (input) INTEGER + The number of rows of the matrix C. M >= 0. + + N (input) INTEGER + The number of columns of the matrix C. N >= 0. + + K (input) INTEGER + The number of elementary reflectors whose product defines + the matrix Q. + If SIDE = 'L', M >= K >= 0; + if SIDE = 'R', N >= K >= 0. + + A (input) REAL array, dimension (LDA,K) + The i-th column must contain the vector which defines the + elementary reflector H(i), for i = 1,2,...,k, as returned by + SGEQLF in the last k columns of its array argument A. + A is modified by the routine but restored on exit. + + LDA (input) INTEGER + The leading dimension of the array A. + If SIDE = 'L', LDA >= max(1,M); + if SIDE = 'R', LDA >= max(1,N). + + TAU (input) REAL array, dimension (K) + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SGEQLF. + + C (input/output) REAL array, dimension (LDC,N) + On entry, the M-by-N matrix C. + On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q. + + LDC (input) INTEGER + The leading dimension of the array C. LDC >= max(1,M). + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. + If SIDE = 'L', LWORK >= max(1,N); + if SIDE = 'R', LWORK >= max(1,M). + For optimum performance LWORK >= N*NB if SIDE = 'L', and + LWORK >= M*NB if SIDE = 'R', where NB is the optimal + blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + *info = 0; + left = lsame_(side, "L"); + notran = lsame_(trans, "N"); + lquery = *lwork == -1; + +/* NQ is the order of Q and NW is the minimum dimension of WORK */ + + if (left) { + nq = *m; + nw = *n; + } else { + nq = *n; + nw = *m; + } + if (! left && ! lsame_(side, "R")) { + *info = -1; + } else if (! notran && ! lsame_(trans, "T")) { + *info = -2; + } else if (*m < 0) { + *info = -3; + } else if (*n < 0) { + *info = -4; + } else if (*k < 0 || *k > nq) { + *info = -5; + } else if (*lda < max(1,nq)) { + *info = -7; + } else if (*ldc < max(1,*m)) { + *info = -10; + } else if (*lwork < max(1,nw) && ! lquery) { + *info = -12; + } + + if (*info == 0) { + +/* + Determine the block size. NB may be at most NBMAX, where NBMAX + is used to define the local array T. + + Computing MIN + Writing concatenation +*/ + i__3[0] = 1, a__1[0] = side; + i__3[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + i__1 = 64, i__2 = ilaenv_(&c__1, "SORMQL", ch__1, m, n, k, &c_n1, ( + ftnlen)6, (ftnlen)2); + nb = min(i__1,i__2); + lwkopt = max(1,nw) * nb; + work[1] = (real) lwkopt; + } + + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORMQL", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0 || *k == 0) { + work[1] = 1.f; + return 0; + } + + nbmin = 2; + ldwork = nw; + if (nb > 1 && nb < *k) { + iws = nw * nb; + if (*lwork < iws) { + nb = *lwork / ldwork; +/* + Computing MAX + Writing concatenation +*/ + i__3[0] = 1, a__1[0] = side; + i__3[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + i__1 = 2, i__2 = ilaenv_(&c__2, "SORMQL", ch__1, m, n, k, &c_n1, ( + ftnlen)6, (ftnlen)2); + nbmin = max(i__1,i__2); + } + } else { + iws = nw; + } + + if (nb < nbmin || nb >= *k) { + +/* Use unblocked code */ + + sorm2l_(side, trans, m, n, k, &a[a_offset], lda, &tau[1], &c__[ + c_offset], ldc, &work[1], &iinfo); + } else { + +/* Use blocked code */ + + if (left && notran || ! left && ! notran) { + i1 = 1; + i2 = *k; + i3 = nb; + } else { + i1 = (*k - 1) / nb * nb + 1; + i2 = 1; + i3 = -nb; + } + + if (left) { + ni = *n; + } else { + mi = *m; + } + + i__1 = i2; + i__2 = i3; + for (i__ = i1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { +/* Computing MIN */ + i__4 = nb, i__5 = *k - i__ + 1; + ib = min(i__4,i__5); + +/* + Form the triangular factor of the block reflector + H = H(i+ib-1) . . . H(i+1) H(i) +*/ + + i__4 = nq - *k + i__ + ib - 1; + slarft_("Backward", "Columnwise", &i__4, &ib, &a[i__ * a_dim1 + 1] + , lda, &tau[i__], t, &c__65); + if (left) { + +/* H or H' is applied to C(1:m-k+i+ib-1,1:n) */ + + mi = *m - *k + i__ + ib - 1; + } else { + +/* H or H' is applied to C(1:m,1:n-k+i+ib-1) */ + + ni = *n - *k + i__ + ib - 1; + } + +/* Apply H or H' */ + + slarfb_(side, trans, "Backward", "Columnwise", &mi, &ni, &ib, &a[ + i__ * a_dim1 + 1], lda, t, &c__65, &c__[c_offset], ldc, & + work[1], &ldwork); +/* L10: */ + } + } + work[1] = (real) lwkopt; + return 0; + +/* End of SORMQL */ + +} /* sormql_ */ + +/* Subroutine */ int sormqr_(char *side, char *trans, integer *m, integer *n, + integer *k, real *a, integer *lda, real *tau, real *c__, integer *ldc, + real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + address a__1[2]; + integer a_dim1, a_offset, c_dim1, c_offset, i__1, i__2, i__3[2], i__4, + i__5; + char ch__1[2]; + + /* Builtin functions */ + /* Subroutine */ int s_cat(char *, char **, integer *, integer *, ftnlen); + + /* Local variables */ + static integer i__; + static real t[4160] /* was [65][64] */; + static integer i1, i2, i3, ib, ic, jc, nb, mi, ni, nq, nw, iws; + static logical left; + extern logical lsame_(char *, char *); + static integer nbmin, iinfo; + extern /* Subroutine */ int sorm2r_(char *, char *, integer *, integer *, + integer *, real *, integer *, real *, real *, integer *, real *, + integer *), slarfb_(char *, char *, char *, char * + , integer *, integer *, integer *, real *, integer *, real *, + integer *, real *, integer *, real *, integer *), xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slarft_(char *, char *, integer *, integer *, + real *, integer *, real *, real *, integer *); + static logical notran; + static integer ldwork, lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SORMQR overwrites the general real M-by-N matrix C with + + SIDE = 'L' SIDE = 'R' + TRANS = 'N': Q * C C * Q + TRANS = 'T': Q**T * C C * Q**T + + where Q is a real orthogonal matrix defined as the product of k + elementary reflectors + + Q = H(1) H(2) . . . H(k) + + as returned by SGEQRF. Q is of order M if SIDE = 'L' and of order N + if SIDE = 'R'. + + Arguments + ========= + + SIDE (input) CHARACTER*1 + = 'L': apply Q or Q**T from the Left; + = 'R': apply Q or Q**T from the Right. + + TRANS (input) CHARACTER*1 + = 'N': No transpose, apply Q; + = 'T': Transpose, apply Q**T. + + M (input) INTEGER + The number of rows of the matrix C. M >= 0. + + N (input) INTEGER + The number of columns of the matrix C. N >= 0. + + K (input) INTEGER + The number of elementary reflectors whose product defines + the matrix Q. + If SIDE = 'L', M >= K >= 0; + if SIDE = 'R', N >= K >= 0. + + A (input) REAL array, dimension (LDA,K) + The i-th column must contain the vector which defines the + elementary reflector H(i), for i = 1,2,...,k, as returned by + SGEQRF in the first k columns of its array argument A. + A is modified by the routine but restored on exit. + + LDA (input) INTEGER + The leading dimension of the array A. + If SIDE = 'L', LDA >= max(1,M); + if SIDE = 'R', LDA >= max(1,N). + + TAU (input) REAL array, dimension (K) + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SGEQRF. + + C (input/output) REAL array, dimension (LDC,N) + On entry, the M-by-N matrix C. + On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q. + + LDC (input) INTEGER + The leading dimension of the array C. LDC >= max(1,M). + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. + If SIDE = 'L', LWORK >= max(1,N); + if SIDE = 'R', LWORK >= max(1,M). + For optimum performance LWORK >= N*NB if SIDE = 'L', and + LWORK >= M*NB if SIDE = 'R', where NB is the optimal + blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + *info = 0; + left = lsame_(side, "L"); + notran = lsame_(trans, "N"); + lquery = *lwork == -1; + +/* NQ is the order of Q and NW is the minimum dimension of WORK */ + + if (left) { + nq = *m; + nw = *n; + } else { + nq = *n; + nw = *m; + } + if (! left && ! lsame_(side, "R")) { + *info = -1; + } else if (! notran && ! lsame_(trans, "T")) { + *info = -2; + } else if (*m < 0) { + *info = -3; + } else if (*n < 0) { + *info = -4; + } else if (*k < 0 || *k > nq) { + *info = -5; + } else if (*lda < max(1,nq)) { + *info = -7; + } else if (*ldc < max(1,*m)) { + *info = -10; + } else if (*lwork < max(1,nw) && ! lquery) { + *info = -12; + } + + if (*info == 0) { + +/* + Determine the block size. NB may be at most NBMAX, where NBMAX + is used to define the local array T. + + Computing MIN + Writing concatenation +*/ + i__3[0] = 1, a__1[0] = side; + i__3[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + i__1 = 64, i__2 = ilaenv_(&c__1, "SORMQR", ch__1, m, n, k, &c_n1, ( + ftnlen)6, (ftnlen)2); + nb = min(i__1,i__2); + lwkopt = max(1,nw) * nb; + work[1] = (real) lwkopt; + } + + if (*info != 0) { + i__1 = -(*info); + xerbla_("SORMQR", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0 || *k == 0) { + work[1] = 1.f; + return 0; + } + + nbmin = 2; + ldwork = nw; + if (nb > 1 && nb < *k) { + iws = nw * nb; + if (*lwork < iws) { + nb = *lwork / ldwork; +/* + Computing MAX + Writing concatenation +*/ + i__3[0] = 1, a__1[0] = side; + i__3[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__3, &c__2, (ftnlen)2); + i__1 = 2, i__2 = ilaenv_(&c__2, "SORMQR", ch__1, m, n, k, &c_n1, ( + ftnlen)6, (ftnlen)2); + nbmin = max(i__1,i__2); + } + } else { + iws = nw; + } + + if (nb < nbmin || nb >= *k) { + +/* Use unblocked code */ + + sorm2r_(side, trans, m, n, k, &a[a_offset], lda, &tau[1], &c__[ + c_offset], ldc, &work[1], &iinfo); + } else { + +/* Use blocked code */ + + if (left && ! notran || ! left && notran) { + i1 = 1; + i2 = *k; + i3 = nb; + } else { + i1 = (*k - 1) / nb * nb + 1; + i2 = 1; + i3 = -nb; + } + + if (left) { + ni = *n; + jc = 1; + } else { + mi = *m; + ic = 1; + } + + i__1 = i2; + i__2 = i3; + for (i__ = i1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) { +/* Computing MIN */ + i__4 = nb, i__5 = *k - i__ + 1; + ib = min(i__4,i__5); + +/* + Form the triangular factor of the block reflector + H = H(i) H(i+1) . . . H(i+ib-1) +*/ + + i__4 = nq - i__ + 1; + slarft_("Forward", "Columnwise", &i__4, &ib, &a[i__ + i__ * + a_dim1], lda, &tau[i__], t, &c__65) + ; + if (left) { + +/* H or H' is applied to C(i:m,1:n) */ + + mi = *m - i__ + 1; + ic = i__; + } else { + +/* H or H' is applied to C(1:m,i:n) */ + + ni = *n - i__ + 1; + jc = i__; + } + +/* Apply H or H' */ + + slarfb_(side, trans, "Forward", "Columnwise", &mi, &ni, &ib, &a[ + i__ + i__ * a_dim1], lda, t, &c__65, &c__[ic + jc * + c_dim1], ldc, &work[1], &ldwork); +/* L10: */ + } + } + work[1] = (real) lwkopt; + return 0; + +/* End of SORMQR */ + +} /* sormqr_ */ + +/* Subroutine */ int sormtr_(char *side, char *uplo, char *trans, integer *m, + integer *n, real *a, integer *lda, real *tau, real *c__, integer *ldc, + real *work, integer *lwork, integer *info) +{ + /* System generated locals */ + address a__1[2]; + integer a_dim1, a_offset, c_dim1, c_offset, i__1[2], i__2, i__3; + char ch__1[2]; + + /* Builtin functions */ + /* Subroutine */ int s_cat(char *, char **, integer *, integer *, ftnlen); + + /* Local variables */ + static integer i1, i2, nb, mi, ni, nq, nw; + static logical left; + extern logical lsame_(char *, char *); + static integer iinfo; + static logical upper; + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int sormql_(char *, char *, integer *, integer *, + integer *, real *, integer *, real *, real *, integer *, real *, + integer *, integer *); + static integer lwkopt; + static logical lquery; + extern /* Subroutine */ int sormqr_(char *, char *, integer *, integer *, + integer *, real *, integer *, real *, real *, integer *, real *, + integer *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SORMTR overwrites the general real M-by-N matrix C with + + SIDE = 'L' SIDE = 'R' + TRANS = 'N': Q * C C * Q + TRANS = 'T': Q**T * C C * Q**T + + where Q is a real orthogonal matrix of order nq, with nq = m if + SIDE = 'L' and nq = n if SIDE = 'R'. Q is defined as the product of + nq-1 elementary reflectors, as returned by SSYTRD: + + if UPLO = 'U', Q = H(nq-1) . . . H(2) H(1); + + if UPLO = 'L', Q = H(1) H(2) . . . H(nq-1). + + Arguments + ========= + + SIDE (input) CHARACTER*1 + = 'L': apply Q or Q**T from the Left; + = 'R': apply Q or Q**T from the Right. + + UPLO (input) CHARACTER*1 + = 'U': Upper triangle of A contains elementary reflectors + from SSYTRD; + = 'L': Lower triangle of A contains elementary reflectors + from SSYTRD. + + TRANS (input) CHARACTER*1 + = 'N': No transpose, apply Q; + = 'T': Transpose, apply Q**T. + + M (input) INTEGER + The number of rows of the matrix C. M >= 0. + + N (input) INTEGER + The number of columns of the matrix C. N >= 0. + + A (input) REAL array, dimension + (LDA,M) if SIDE = 'L' + (LDA,N) if SIDE = 'R' + The vectors which define the elementary reflectors, as + returned by SSYTRD. + + LDA (input) INTEGER + The leading dimension of the array A. + LDA >= max(1,M) if SIDE = 'L'; LDA >= max(1,N) if SIDE = 'R'. + + TAU (input) REAL array, dimension + (M-1) if SIDE = 'L' + (N-1) if SIDE = 'R' + TAU(i) must contain the scalar factor of the elementary + reflector H(i), as returned by SSYTRD. + + C (input/output) REAL array, dimension (LDC,N) + On entry, the M-by-N matrix C. + On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q. + + LDC (input) INTEGER + The leading dimension of the array C. LDC >= max(1,M). + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. + If SIDE = 'L', LWORK >= max(1,N); + if SIDE = 'R', LWORK >= max(1,M). + For optimum performance LWORK >= N*NB if SIDE = 'L', and + LWORK >= M*NB if SIDE = 'R', where NB is the optimal + blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input arguments +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --tau; + c_dim1 = *ldc; + c_offset = 1 + c_dim1; + c__ -= c_offset; + --work; + + /* Function Body */ + *info = 0; + left = lsame_(side, "L"); + upper = lsame_(uplo, "U"); + lquery = *lwork == -1; + +/* NQ is the order of Q and NW is the minimum dimension of WORK */ + + if (left) { + nq = *m; + nw = *n; + } else { + nq = *n; + nw = *m; + } + if (! left && ! lsame_(side, "R")) { + *info = -1; + } else if (! upper && ! lsame_(uplo, "L")) { + *info = -2; + } else if (! lsame_(trans, "N") && ! lsame_(trans, + "T")) { + *info = -3; + } else if (*m < 0) { + *info = -4; + } else if (*n < 0) { + *info = -5; + } else if (*lda < max(1,nq)) { + *info = -7; + } else if (*ldc < max(1,*m)) { + *info = -10; + } else if (*lwork < max(1,nw) && ! lquery) { + *info = -12; + } + + if (*info == 0) { + if (upper) { + if (left) { +/* Writing concatenation */ + i__1[0] = 1, a__1[0] = side; + i__1[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__1, &c__2, (ftnlen)2); + i__2 = *m - 1; + i__3 = *m - 1; + nb = ilaenv_(&c__1, "SORMQL", ch__1, &i__2, n, &i__3, &c_n1, ( + ftnlen)6, (ftnlen)2); + } else { +/* Writing concatenation */ + i__1[0] = 1, a__1[0] = side; + i__1[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__1, &c__2, (ftnlen)2); + i__2 = *n - 1; + i__3 = *n - 1; + nb = ilaenv_(&c__1, "SORMQL", ch__1, m, &i__2, &i__3, &c_n1, ( + ftnlen)6, (ftnlen)2); + } + } else { + if (left) { +/* Writing concatenation */ + i__1[0] = 1, a__1[0] = side; + i__1[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__1, &c__2, (ftnlen)2); + i__2 = *m - 1; + i__3 = *m - 1; + nb = ilaenv_(&c__1, "SORMQR", ch__1, &i__2, n, &i__3, &c_n1, ( + ftnlen)6, (ftnlen)2); + } else { +/* Writing concatenation */ + i__1[0] = 1, a__1[0] = side; + i__1[1] = 1, a__1[1] = trans; + s_cat(ch__1, a__1, i__1, &c__2, (ftnlen)2); + i__2 = *n - 1; + i__3 = *n - 1; + nb = ilaenv_(&c__1, "SORMQR", ch__1, m, &i__2, &i__3, &c_n1, ( + ftnlen)6, (ftnlen)2); + } + } + lwkopt = max(1,nw) * nb; + work[1] = (real) lwkopt; + } + + if (*info != 0) { + i__2 = -(*info); + xerbla_("SORMTR", &i__2); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*m == 0 || *n == 0 || nq == 1) { + work[1] = 1.f; + return 0; + } + + if (left) { + mi = *m - 1; + ni = *n; + } else { + mi = *m; + ni = *n - 1; + } + + if (upper) { + +/* Q was determined by a call to SSYTRD with UPLO = 'U' */ + + i__2 = nq - 1; + sormql_(side, trans, &mi, &ni, &i__2, &a[(a_dim1 << 1) + 1], lda, & + tau[1], &c__[c_offset], ldc, &work[1], lwork, &iinfo); + } else { + +/* Q was determined by a call to SSYTRD with UPLO = 'L' */ + + if (left) { + i1 = 2; + i2 = 1; + } else { + i1 = 1; + i2 = 2; + } + i__2 = nq - 1; + sormqr_(side, trans, &mi, &ni, &i__2, &a[a_dim1 + 2], lda, &tau[1], & + c__[i1 + i2 * c_dim1], ldc, &work[1], lwork, &iinfo); + } + work[1] = (real) lwkopt; + return 0; + +/* End of SORMTR */ + +} /* sormtr_ */ + +/* Subroutine */ int spotf2_(char *uplo, integer *n, real *a, integer *lda, + integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + real r__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static integer j; + static real ajj; + extern doublereal sdot_(integer *, real *, integer *, real *, integer *); + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *), + sgemv_(char *, integer *, integer *, real *, real *, integer *, + real *, integer *, real *, real *, integer *); + static logical upper; + extern /* Subroutine */ int xerbla_(char *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + SPOTF2 computes the Cholesky factorization of a real symmetric + positive definite matrix A. + + The factorization has the form + A = U' * U , if UPLO = 'U', or + A = L * L', if UPLO = 'L', + where U is an upper triangular matrix and L is lower triangular. + + This is the unblocked version of the algorithm, calling Level 2 BLAS. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + Specifies whether the upper or lower triangular part of the + symmetric matrix A is stored. + = 'U': Upper triangular + = 'L': Lower triangular + + N (input) INTEGER + The order of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the symmetric matrix A. If UPLO = 'U', the leading + n by n upper triangular part of A contains the upper + triangular part of the matrix A, and the strictly lower + triangular part of A is not referenced. If UPLO = 'L', the + leading n by n lower triangular part of A contains the lower + triangular part of the matrix A, and the strictly upper + triangular part of A is not referenced. + + On exit, if INFO = 0, the factor U or L from the Cholesky + factorization A = U'*U or A = L*L'. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -k, the k-th argument had an illegal value + > 0: if INFO = k, the leading minor of order k is not + positive definite, and the factorization could not be + completed. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + + /* Function Body */ + *info = 0; + upper = lsame_(uplo, "U"); + if (! upper && ! lsame_(uplo, "L")) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*n)) { + *info = -4; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SPOTF2", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + + if (upper) { + +/* Compute the Cholesky factorization A = U'*U. */ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + +/* Compute U(J,J) and test for non-positive-definiteness. */ + + i__2 = j - 1; + ajj = a[j + j * a_dim1] - sdot_(&i__2, &a[j * a_dim1 + 1], &c__1, + &a[j * a_dim1 + 1], &c__1); + if (ajj <= 0.f) { + a[j + j * a_dim1] = ajj; + goto L30; + } + ajj = sqrt(ajj); + a[j + j * a_dim1] = ajj; + +/* Compute elements J+1:N of row J. */ + + if (j < *n) { + i__2 = j - 1; + i__3 = *n - j; + sgemv_("Transpose", &i__2, &i__3, &c_b151, &a[(j + 1) * + a_dim1 + 1], lda, &a[j * a_dim1 + 1], &c__1, &c_b15, & + a[j + (j + 1) * a_dim1], lda); + i__2 = *n - j; + r__1 = 1.f / ajj; + sscal_(&i__2, &r__1, &a[j + (j + 1) * a_dim1], lda); + } +/* L10: */ + } + } else { + +/* Compute the Cholesky factorization A = L*L'. */ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + +/* Compute L(J,J) and test for non-positive-definiteness. */ + + i__2 = j - 1; + ajj = a[j + j * a_dim1] - sdot_(&i__2, &a[j + a_dim1], lda, &a[j + + a_dim1], lda); + if (ajj <= 0.f) { + a[j + j * a_dim1] = ajj; + goto L30; + } + ajj = sqrt(ajj); + a[j + j * a_dim1] = ajj; + +/* Compute elements J+1:N of column J. */ + + if (j < *n) { + i__2 = *n - j; + i__3 = j - 1; + sgemv_("No transpose", &i__2, &i__3, &c_b151, &a[j + 1 + + a_dim1], lda, &a[j + a_dim1], lda, &c_b15, &a[j + 1 + + j * a_dim1], &c__1); + i__2 = *n - j; + r__1 = 1.f / ajj; + sscal_(&i__2, &r__1, &a[j + 1 + j * a_dim1], &c__1); + } +/* L20: */ + } + } + goto L40; + +L30: + *info = j; + +L40: + return 0; + +/* End of SPOTF2 */ + +} /* spotf2_ */ + +/* Subroutine */ int spotrf_(char *uplo, integer *n, real *a, integer *lda, + integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3, i__4; + + /* Local variables */ + static integer j, jb, nb; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *); + static logical upper; + extern /* Subroutine */ int strsm_(char *, char *, char *, char *, + integer *, integer *, real *, real *, integer *, real *, integer * + ), ssyrk_(char *, char *, integer + *, integer *, real *, real *, integer *, real *, real *, integer * + ), spotf2_(char *, integer *, real *, integer *, + integer *), xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + March 31, 1993 + + + Purpose + ======= + + SPOTRF computes the Cholesky factorization of a real symmetric + positive definite matrix A. + + The factorization has the form + A = U**T * U, if UPLO = 'U', or + A = L * L**T, if UPLO = 'L', + where U is an upper triangular matrix and L is lower triangular. + + This is the block version of the algorithm, calling Level 3 BLAS. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + = 'U': Upper triangle of A is stored; + = 'L': Lower triangle of A is stored. + + N (input) INTEGER + The order of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the symmetric matrix A. If UPLO = 'U', the leading + N-by-N upper triangular part of A contains the upper + triangular part of the matrix A, and the strictly lower + triangular part of A is not referenced. If UPLO = 'L', the + leading N-by-N lower triangular part of A contains the lower + triangular part of the matrix A, and the strictly upper + triangular part of A is not referenced. + + On exit, if INFO = 0, the factor U or L from the Cholesky + factorization A = U**T*U or A = L*L**T. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + > 0: if INFO = i, the leading minor of order i is not + positive definite, and the factorization could not be + completed. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + + /* Function Body */ + *info = 0; + upper = lsame_(uplo, "U"); + if (! upper && ! lsame_(uplo, "L")) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*n)) { + *info = -4; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SPOTRF", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + +/* Determine the block size for this environment. */ + + nb = ilaenv_(&c__1, "SPOTRF", uplo, n, &c_n1, &c_n1, &c_n1, (ftnlen)6, ( + ftnlen)1); + if (nb <= 1 || nb >= *n) { + +/* Use unblocked code. */ + + spotf2_(uplo, n, &a[a_offset], lda, info); + } else { + +/* Use blocked code. */ + + if (upper) { + +/* Compute the Cholesky factorization A = U'*U. */ + + i__1 = *n; + i__2 = nb; + for (j = 1; i__2 < 0 ? j >= i__1 : j <= i__1; j += i__2) { + +/* + Update and factorize the current diagonal block and test + for non-positive-definiteness. + + Computing MIN +*/ + i__3 = nb, i__4 = *n - j + 1; + jb = min(i__3,i__4); + i__3 = j - 1; + ssyrk_("Upper", "Transpose", &jb, &i__3, &c_b151, &a[j * + a_dim1 + 1], lda, &c_b15, &a[j + j * a_dim1], lda); + spotf2_("Upper", &jb, &a[j + j * a_dim1], lda, info); + if (*info != 0) { + goto L30; + } + if (j + jb <= *n) { + +/* Compute the current block row. */ + + i__3 = *n - j - jb + 1; + i__4 = j - 1; + sgemm_("Transpose", "No transpose", &jb, &i__3, &i__4, & + c_b151, &a[j * a_dim1 + 1], lda, &a[(j + jb) * + a_dim1 + 1], lda, &c_b15, &a[j + (j + jb) * + a_dim1], lda); + i__3 = *n - j - jb + 1; + strsm_("Left", "Upper", "Transpose", "Non-unit", &jb, & + i__3, &c_b15, &a[j + j * a_dim1], lda, &a[j + (j + + jb) * a_dim1], lda); + } +/* L10: */ + } + + } else { + +/* Compute the Cholesky factorization A = L*L'. */ + + i__2 = *n; + i__1 = nb; + for (j = 1; i__1 < 0 ? j >= i__2 : j <= i__2; j += i__1) { + +/* + Update and factorize the current diagonal block and test + for non-positive-definiteness. + + Computing MIN +*/ + i__3 = nb, i__4 = *n - j + 1; + jb = min(i__3,i__4); + i__3 = j - 1; + ssyrk_("Lower", "No transpose", &jb, &i__3, &c_b151, &a[j + + a_dim1], lda, &c_b15, &a[j + j * a_dim1], lda); + spotf2_("Lower", &jb, &a[j + j * a_dim1], lda, info); + if (*info != 0) { + goto L30; + } + if (j + jb <= *n) { + +/* Compute the current block column. */ + + i__3 = *n - j - jb + 1; + i__4 = j - 1; + sgemm_("No transpose", "Transpose", &i__3, &jb, &i__4, & + c_b151, &a[j + jb + a_dim1], lda, &a[j + a_dim1], + lda, &c_b15, &a[j + jb + j * a_dim1], lda); + i__3 = *n - j - jb + 1; + strsm_("Right", "Lower", "Transpose", "Non-unit", &i__3, & + jb, &c_b15, &a[j + j * a_dim1], lda, &a[j + jb + + j * a_dim1], lda); + } +/* L20: */ + } + } + } + goto L40; + +L30: + *info = *info + j - 1; + +L40: + return 0; + +/* End of SPOTRF */ + +} /* spotrf_ */ + +/* Subroutine */ int spotri_(char *uplo, integer *n, real *a, integer *lda, + integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1; + + /* Local variables */ + extern logical lsame_(char *, char *); + extern /* Subroutine */ int xerbla_(char *, integer *), slauum_( + char *, integer *, real *, integer *, integer *), strtri_( + char *, char *, integer *, real *, integer *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + March 31, 1993 + + + Purpose + ======= + + SPOTRI computes the inverse of a real symmetric positive definite + matrix A using the Cholesky factorization A = U**T*U or A = L*L**T + computed by SPOTRF. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + = 'U': Upper triangle of A is stored; + = 'L': Lower triangle of A is stored. + + N (input) INTEGER + The order of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the triangular factor U or L from the Cholesky + factorization A = U**T*U or A = L*L**T, as computed by + SPOTRF. + On exit, the upper or lower triangle of the (symmetric) + inverse of A, overwriting the input factor U or L. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + > 0: if INFO = i, the (i,i) element of the factor U or L is + zero, and the inverse could not be computed. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + + /* Function Body */ + *info = 0; + if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*n)) { + *info = -4; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SPOTRI", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + +/* Invert the triangular Cholesky factor U or L. */ + + strtri_(uplo, "Non-unit", n, &a[a_offset], lda, info); + if (*info > 0) { + return 0; + } + +/* Form inv(U)*inv(U)' or inv(L)'*inv(L). */ + + slauum_(uplo, n, &a[a_offset], lda, info); + + return 0; + +/* End of SPOTRI */ + +} /* spotri_ */ + +/* Subroutine */ int spotrs_(char *uplo, integer *n, integer *nrhs, real *a, + integer *lda, real *b, integer *ldb, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, b_dim1, b_offset, i__1; + + /* Local variables */ + extern logical lsame_(char *, char *); + static logical upper; + extern /* Subroutine */ int strsm_(char *, char *, char *, char *, + integer *, integer *, real *, real *, integer *, real *, integer * + ), xerbla_(char *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + March 31, 1993 + + + Purpose + ======= + + SPOTRS solves a system of linear equations A*X = B with a symmetric + positive definite matrix A using the Cholesky factorization + A = U**T*U or A = L*L**T computed by SPOTRF. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + = 'U': Upper triangle of A is stored; + = 'L': Lower triangle of A is stored. + + N (input) INTEGER + The order of the matrix A. N >= 0. + + NRHS (input) INTEGER + The number of right hand sides, i.e., the number of columns + of the matrix B. NRHS >= 0. + + A (input) REAL array, dimension (LDA,N) + The triangular factor U or L from the Cholesky factorization + A = U**T*U or A = L*L**T, as computed by SPOTRF. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + B (input/output) REAL array, dimension (LDB,NRHS) + On entry, the right hand side matrix B. + On exit, the solution matrix X. + + LDB (input) INTEGER + The leading dimension of the array B. LDB >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + b_dim1 = *ldb; + b_offset = 1 + b_dim1; + b -= b_offset; + + /* Function Body */ + *info = 0; + upper = lsame_(uplo, "U"); + if (! upper && ! lsame_(uplo, "L")) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*nrhs < 0) { + *info = -3; + } else if (*lda < max(1,*n)) { + *info = -5; + } else if (*ldb < max(1,*n)) { + *info = -7; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SPOTRS", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0 || *nrhs == 0) { + return 0; + } + + if (upper) { + +/* + Solve A*X = B where A = U'*U. + + Solve U'*X = B, overwriting B with X. +*/ + + strsm_("Left", "Upper", "Transpose", "Non-unit", n, nrhs, &c_b15, &a[ + a_offset], lda, &b[b_offset], ldb); + +/* Solve U*X = B, overwriting B with X. */ + + strsm_("Left", "Upper", "No transpose", "Non-unit", n, nrhs, &c_b15, & + a[a_offset], lda, &b[b_offset], ldb); + } else { + +/* + Solve A*X = B where A = L*L'. + + Solve L*X = B, overwriting B with X. +*/ + + strsm_("Left", "Lower", "No transpose", "Non-unit", n, nrhs, &c_b15, & + a[a_offset], lda, &b[b_offset], ldb); + +/* Solve L'*X = B, overwriting B with X. */ + + strsm_("Left", "Lower", "Transpose", "Non-unit", n, nrhs, &c_b15, &a[ + a_offset], lda, &b[b_offset], ldb); + } + + return 0; + +/* End of SPOTRS */ + +} /* spotrs_ */ + +/* Subroutine */ int sstedc_(char *compz, integer *n, real *d__, real *e, + real *z__, integer *ldz, real *work, integer *lwork, integer *iwork, + integer *liwork, integer *info) +{ + /* System generated locals */ + integer z_dim1, z_offset, i__1, i__2; + real r__1, r__2; + + /* Builtin functions */ + double log(doublereal); + integer pow_ii(integer *, integer *); + double sqrt(doublereal); + + /* Local variables */ + static integer i__, j, k, m; + static real p; + static integer ii, end, lgn; + static real eps, tiny; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, + integer *, real *, real *, integer *, real *, integer *, real *, + real *, integer *); + static integer lwmin, start; + extern /* Subroutine */ int sswap_(integer *, real *, integer *, real *, + integer *), slaed0_(integer *, integer *, integer *, real *, real + *, real *, integer *, real *, integer *, real *, integer *, + integer *); + extern doublereal slamch_(char *); + extern /* Subroutine */ int xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *, + real *, integer *, integer *, real *, integer *, integer *), slacpy_(char *, integer *, integer *, real *, integer *, + real *, integer *), slaset_(char *, integer *, integer *, + real *, real *, real *, integer *); + static integer liwmin, icompz; + static real orgnrm; + extern doublereal slanst_(char *, integer *, real *, real *); + extern /* Subroutine */ int ssterf_(integer *, real *, real *, integer *), + slasrt_(char *, integer *, real *, integer *); + static logical lquery; + static integer smlsiz; + extern /* Subroutine */ int ssteqr_(char *, integer *, real *, real *, + real *, integer *, real *, integer *); + static integer storez, strtrw; + + +/* + -- LAPACK driver routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SSTEDC computes all eigenvalues and, optionally, eigenvectors of a + symmetric tridiagonal matrix using the divide and conquer method. + The eigenvectors of a full or band real symmetric matrix can also be + found if SSYTRD or SSPTRD or SSBTRD has been used to reduce this + matrix to tridiagonal form. + + This code makes very mild assumptions about floating point + arithmetic. It will work on machines with a guard digit in + add/subtract, or on those binary machines without guard digits + which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or Cray-2. + It could conceivably fail on hexadecimal or decimal machines + without guard digits, but we know of none. See SLAED3 for details. + + Arguments + ========= + + COMPZ (input) CHARACTER*1 + = 'N': Compute eigenvalues only. + = 'I': Compute eigenvectors of tridiagonal matrix also. + = 'V': Compute eigenvectors of original dense symmetric + matrix also. On entry, Z contains the orthogonal + matrix used to reduce the original matrix to + tridiagonal form. + + N (input) INTEGER + The dimension of the symmetric tridiagonal matrix. N >= 0. + + D (input/output) REAL array, dimension (N) + On entry, the diagonal elements of the tridiagonal matrix. + On exit, if INFO = 0, the eigenvalues in ascending order. + + E (input/output) REAL array, dimension (N-1) + On entry, the subdiagonal elements of the tridiagonal matrix. + On exit, E has been destroyed. + + Z (input/output) REAL array, dimension (LDZ,N) + On entry, if COMPZ = 'V', then Z contains the orthogonal + matrix used in the reduction to tridiagonal form. + On exit, if INFO = 0, then if COMPZ = 'V', Z contains the + orthonormal eigenvectors of the original symmetric matrix, + and if COMPZ = 'I', Z contains the orthonormal eigenvectors + of the symmetric tridiagonal matrix. + If COMPZ = 'N', then Z is not referenced. + + LDZ (input) INTEGER + The leading dimension of the array Z. LDZ >= 1. + If eigenvectors are desired, then LDZ >= max(1,N). + + WORK (workspace/output) REAL array, + dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. + If COMPZ = 'N' or N <= 1 then LWORK must be at least 1. + If COMPZ = 'V' and N > 1 then LWORK must be at least + ( 1 + 3*N + 2*N*lg N + 3*N**2 ), + where lg( N ) = smallest integer k such + that 2**k >= N. + If COMPZ = 'I' and N > 1 then LWORK must be at least + ( 1 + 4*N + N**2 ). + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + IWORK (workspace/output) INTEGER array, dimension (LIWORK) + On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK. + + LIWORK (input) INTEGER + The dimension of the array IWORK. + If COMPZ = 'N' or N <= 1 then LIWORK must be at least 1. + If COMPZ = 'V' and N > 1 then LIWORK must be at least + ( 6 + 6*N + 5*N*lg N ). + If COMPZ = 'I' and N > 1 then LIWORK must be at least + ( 3 + 5*N ). + + If LIWORK = -1, then a workspace query is assumed; the + routine only calculates the optimal size of the IWORK array, + returns this value as the first entry of the IWORK array, and + no error message related to LIWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit. + < 0: if INFO = -i, the i-th argument had an illegal value. + > 0: The algorithm failed to compute an eigenvalue while + working on the submatrix lying in rows and columns + INFO/(N+1) through mod(INFO,N+1). + + Further Details + =============== + + Based on contributions by + Jeff Rutter, Computer Science Division, University of California + at Berkeley, USA + Modified by Francoise Tisseur, University of Tennessee. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --e; + z_dim1 = *ldz; + z_offset = 1 + z_dim1; + z__ -= z_offset; + --work; + --iwork; + + /* Function Body */ + *info = 0; + lquery = *lwork == -1 || *liwork == -1; + + if (lsame_(compz, "N")) { + icompz = 0; + } else if (lsame_(compz, "V")) { + icompz = 1; + } else if (lsame_(compz, "I")) { + icompz = 2; + } else { + icompz = -1; + } + if (*n <= 1 || icompz <= 0) { + liwmin = 1; + lwmin = 1; + } else { + lgn = (integer) (log((real) (*n)) / log(2.f)); + if (pow_ii(&c__2, &lgn) < *n) { + ++lgn; + } + if (pow_ii(&c__2, &lgn) < *n) { + ++lgn; + } + if (icompz == 1) { +/* Computing 2nd power */ + i__1 = *n; + lwmin = *n * 3 + 1 + (*n << 1) * lgn + i__1 * i__1 * 3; + liwmin = *n * 6 + 6 + *n * 5 * lgn; + } else if (icompz == 2) { +/* Computing 2nd power */ + i__1 = *n; + lwmin = (*n << 2) + 1 + i__1 * i__1; + liwmin = *n * 5 + 3; + } + } + if (icompz < 0) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*ldz < 1 || icompz > 0 && *ldz < max(1,*n)) { + *info = -6; + } else if (*lwork < lwmin && ! lquery) { + *info = -8; + } else if (*liwork < liwmin && ! lquery) { + *info = -10; + } + + if (*info == 0) { + work[1] = (real) lwmin; + iwork[1] = liwmin; + } + + if (*info != 0) { + i__1 = -(*info); + xerbla_("SSTEDC", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + if (*n == 1) { + if (icompz != 0) { + z__[z_dim1 + 1] = 1.f; + } + return 0; + } + + smlsiz = ilaenv_(&c__9, "SSTEDC", " ", &c__0, &c__0, &c__0, &c__0, ( + ftnlen)6, (ftnlen)1); + +/* + If the following conditional clause is removed, then the routine + will use the Divide and Conquer routine to compute only the + eigenvalues, which requires (3N + 3N**2) real workspace and + (2 + 5N + 2N lg(N)) integer workspace. + Since on many architectures SSTERF is much faster than any other + algorithm for finding eigenvalues only, it is used here + as the default. + + If COMPZ = 'N', use SSTERF to compute the eigenvalues. +*/ + + if (icompz == 0) { + ssterf_(n, &d__[1], &e[1], info); + return 0; + } + +/* + If N is smaller than the minimum divide size (SMLSIZ+1), then + solve the problem with another solver. +*/ + + if (*n <= smlsiz) { + if (icompz == 0) { + ssterf_(n, &d__[1], &e[1], info); + return 0; + } else if (icompz == 2) { + ssteqr_("I", n, &d__[1], &e[1], &z__[z_offset], ldz, &work[1], + info); + return 0; + } else { + ssteqr_("V", n, &d__[1], &e[1], &z__[z_offset], ldz, &work[1], + info); + return 0; + } + } + +/* + If COMPZ = 'V', the Z matrix must be stored elsewhere for later + use. +*/ + + if (icompz == 1) { + storez = *n * *n + 1; + } else { + storez = 1; + } + + if (icompz == 2) { + slaset_("Full", n, n, &c_b29, &c_b15, &z__[z_offset], ldz); + } + +/* Scale. */ + + orgnrm = slanst_("M", n, &d__[1], &e[1]); + if (orgnrm == 0.f) { + return 0; + } + + eps = slamch_("Epsilon"); + + start = 1; + +/* while ( START <= N ) */ + +L10: + if (start <= *n) { + +/* + Let END be the position of the next subdiagonal entry such that + E( END ) <= TINY or END = N if no such subdiagonal exists. The + matrix identified by the elements between START and END + constitutes an independent sub-problem. +*/ + + end = start; +L20: + if (end < *n) { + tiny = eps * sqrt((r__1 = d__[end], dabs(r__1))) * sqrt((r__2 = + d__[end + 1], dabs(r__2))); + if ((r__1 = e[end], dabs(r__1)) > tiny) { + ++end; + goto L20; + } + } + +/* (Sub) Problem determined. Compute its size and solve it. */ + + m = end - start + 1; + if (m == 1) { + start = end + 1; + goto L10; + } + if (m > smlsiz) { + *info = smlsiz; + +/* Scale. */ + + orgnrm = slanst_("M", &m, &d__[start], &e[start]); + slascl_("G", &c__0, &c__0, &orgnrm, &c_b15, &m, &c__1, &d__[start] + , &m, info); + i__1 = m - 1; + i__2 = m - 1; + slascl_("G", &c__0, &c__0, &orgnrm, &c_b15, &i__1, &c__1, &e[ + start], &i__2, info); + + if (icompz == 1) { + strtrw = 1; + } else { + strtrw = start; + } + slaed0_(&icompz, n, &m, &d__[start], &e[start], &z__[strtrw + + start * z_dim1], ldz, &work[1], n, &work[storez], &iwork[ + 1], info); + if (*info != 0) { + *info = (*info / (m + 1) + start - 1) * (*n + 1) + *info % (m + + 1) + start - 1; + return 0; + } + +/* Scale back. */ + + slascl_("G", &c__0, &c__0, &c_b15, &orgnrm, &m, &c__1, &d__[start] + , &m, info); + + } else { + if (icompz == 1) { + +/* + Since QR won't update a Z matrix which is larger than the + length of D, we must solve the sub-problem in a workspace and + then multiply back into Z. +*/ + + ssteqr_("I", &m, &d__[start], &e[start], &work[1], &m, &work[ + m * m + 1], info); + slacpy_("A", n, &m, &z__[start * z_dim1 + 1], ldz, &work[ + storez], n); + sgemm_("N", "N", n, &m, &m, &c_b15, &work[storez], ldz, &work[ + 1], &m, &c_b29, &z__[start * z_dim1 + 1], ldz); + } else if (icompz == 2) { + ssteqr_("I", &m, &d__[start], &e[start], &z__[start + start * + z_dim1], ldz, &work[1], info); + } else { + ssterf_(&m, &d__[start], &e[start], info); + } + if (*info != 0) { + *info = start * (*n + 1) + end; + return 0; + } + } + + start = end + 1; + goto L10; + } + +/* + endwhile + + If the problem split any number of times, then the eigenvalues + will not be properly ordered. Here we permute the eigenvalues + (and the associated eigenvectors) into ascending order. +*/ + + if (m != *n) { + if (icompz == 0) { + +/* Use Quick Sort */ + + slasrt_("I", n, &d__[1], info); + + } else { + +/* Use Selection Sort to minimize swaps of eigenvectors */ + + i__1 = *n; + for (ii = 2; ii <= i__1; ++ii) { + i__ = ii - 1; + k = i__; + p = d__[i__]; + i__2 = *n; + for (j = ii; j <= i__2; ++j) { + if (d__[j] < p) { + k = j; + p = d__[j]; + } +/* L30: */ + } + if (k != i__) { + d__[k] = d__[i__]; + d__[i__] = p; + sswap_(n, &z__[i__ * z_dim1 + 1], &c__1, &z__[k * z_dim1 + + 1], &c__1); + } +/* L40: */ + } + } + } + + work[1] = (real) lwmin; + iwork[1] = liwmin; + + return 0; + +/* End of SSTEDC */ + +} /* sstedc_ */ + +/* Subroutine */ int ssteqr_(char *compz, integer *n, real *d__, real *e, + real *z__, integer *ldz, real *work, integer *info) +{ + /* System generated locals */ + integer z_dim1, z_offset, i__1, i__2; + real r__1, r__2; + + /* Builtin functions */ + double sqrt(doublereal), r_sign(real *, real *); + + /* Local variables */ + static real b, c__, f, g; + static integer i__, j, k, l, m; + static real p, r__, s; + static integer l1, ii, mm, lm1, mm1, nm1; + static real rt1, rt2, eps; + static integer lsv; + static real tst, eps2; + static integer lend, jtot; + extern /* Subroutine */ int slae2_(real *, real *, real *, real *, real *) + ; + extern logical lsame_(char *, char *); + static real anorm; + extern /* Subroutine */ int slasr_(char *, char *, char *, integer *, + integer *, real *, real *, real *, integer *), sswap_(integer *, real *, integer *, real *, integer *); + static integer lendm1, lendp1; + extern /* Subroutine */ int slaev2_(real *, real *, real *, real *, real * + , real *, real *); + extern doublereal slapy2_(real *, real *); + static integer iscale; + extern doublereal slamch_(char *); + static real safmin; + extern /* Subroutine */ int xerbla_(char *, integer *); + static real safmax; + extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *, + real *, integer *, integer *, real *, integer *, integer *); + static integer lendsv; + extern /* Subroutine */ int slartg_(real *, real *, real *, real *, real * + ), slaset_(char *, integer *, integer *, real *, real *, real *, + integer *); + static real ssfmin; + static integer nmaxit, icompz; + static real ssfmax; + extern doublereal slanst_(char *, integer *, real *, real *); + extern /* Subroutine */ int slasrt_(char *, integer *, real *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + September 30, 1994 + + + Purpose + ======= + + SSTEQR computes all eigenvalues and, optionally, eigenvectors of a + symmetric tridiagonal matrix using the implicit QL or QR method. + The eigenvectors of a full or band symmetric matrix can also be found + if SSYTRD or SSPTRD or SSBTRD has been used to reduce this matrix to + tridiagonal form. + + Arguments + ========= + + COMPZ (input) CHARACTER*1 + = 'N': Compute eigenvalues only. + = 'V': Compute eigenvalues and eigenvectors of the original + symmetric matrix. On entry, Z must contain the + orthogonal matrix used to reduce the original matrix + to tridiagonal form. + = 'I': Compute eigenvalues and eigenvectors of the + tridiagonal matrix. Z is initialized to the identity + matrix. + + N (input) INTEGER + The order of the matrix. N >= 0. + + D (input/output) REAL array, dimension (N) + On entry, the diagonal elements of the tridiagonal matrix. + On exit, if INFO = 0, the eigenvalues in ascending order. + + E (input/output) REAL array, dimension (N-1) + On entry, the (n-1) subdiagonal elements of the tridiagonal + matrix. + On exit, E has been destroyed. + + Z (input/output) REAL array, dimension (LDZ, N) + On entry, if COMPZ = 'V', then Z contains the orthogonal + matrix used in the reduction to tridiagonal form. + On exit, if INFO = 0, then if COMPZ = 'V', Z contains the + orthonormal eigenvectors of the original symmetric matrix, + and if COMPZ = 'I', Z contains the orthonormal eigenvectors + of the symmetric tridiagonal matrix. + If COMPZ = 'N', then Z is not referenced. + + LDZ (input) INTEGER + The leading dimension of the array Z. LDZ >= 1, and if + eigenvectors are desired, then LDZ >= max(1,N). + + WORK (workspace) REAL array, dimension (max(1,2*N-2)) + If COMPZ = 'N', then WORK is not referenced. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + > 0: the algorithm has failed to find all the eigenvalues in + a total of 30*N iterations; if INFO = i, then i + elements of E have not converged to zero; on exit, D + and E contain the elements of a symmetric tridiagonal + matrix which is orthogonally similar to the original + matrix. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --d__; + --e; + z_dim1 = *ldz; + z_offset = 1 + z_dim1; + z__ -= z_offset; + --work; + + /* Function Body */ + *info = 0; + + if (lsame_(compz, "N")) { + icompz = 0; + } else if (lsame_(compz, "V")) { + icompz = 1; + } else if (lsame_(compz, "I")) { + icompz = 2; + } else { + icompz = -1; + } + if (icompz < 0) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*ldz < 1 || icompz > 0 && *ldz < max(1,*n)) { + *info = -6; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SSTEQR", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + + if (*n == 1) { + if (icompz == 2) { + z__[z_dim1 + 1] = 1.f; + } + return 0; + } + +/* Determine the unit roundoff and over/underflow thresholds. */ + + eps = slamch_("E"); +/* Computing 2nd power */ + r__1 = eps; + eps2 = r__1 * r__1; + safmin = slamch_("S"); + safmax = 1.f / safmin; + ssfmax = sqrt(safmax) / 3.f; + ssfmin = sqrt(safmin) / eps2; + +/* + Compute the eigenvalues and eigenvectors of the tridiagonal + matrix. +*/ + + if (icompz == 2) { + slaset_("Full", n, n, &c_b29, &c_b15, &z__[z_offset], ldz); + } + + nmaxit = *n * 30; + jtot = 0; + +/* + Determine where the matrix splits and choose QL or QR iteration + for each block, according to whether top or bottom diagonal + element is smaller. +*/ + + l1 = 1; + nm1 = *n - 1; + +L10: + if (l1 > *n) { + goto L160; + } + if (l1 > 1) { + e[l1 - 1] = 0.f; + } + if (l1 <= nm1) { + i__1 = nm1; + for (m = l1; m <= i__1; ++m) { + tst = (r__1 = e[m], dabs(r__1)); + if (tst == 0.f) { + goto L30; + } + if (tst <= sqrt((r__1 = d__[m], dabs(r__1))) * sqrt((r__2 = d__[m + + 1], dabs(r__2))) * eps) { + e[m] = 0.f; + goto L30; + } +/* L20: */ + } + } + m = *n; + +L30: + l = l1; + lsv = l; + lend = m; + lendsv = lend; + l1 = m + 1; + if (lend == l) { + goto L10; + } + +/* Scale submatrix in rows and columns L to LEND */ + + i__1 = lend - l + 1; + anorm = slanst_("I", &i__1, &d__[l], &e[l]); + iscale = 0; + if (anorm == 0.f) { + goto L10; + } + if (anorm > ssfmax) { + iscale = 1; + i__1 = lend - l + 1; + slascl_("G", &c__0, &c__0, &anorm, &ssfmax, &i__1, &c__1, &d__[l], n, + info); + i__1 = lend - l; + slascl_("G", &c__0, &c__0, &anorm, &ssfmax, &i__1, &c__1, &e[l], n, + info); + } else if (anorm < ssfmin) { + iscale = 2; + i__1 = lend - l + 1; + slascl_("G", &c__0, &c__0, &anorm, &ssfmin, &i__1, &c__1, &d__[l], n, + info); + i__1 = lend - l; + slascl_("G", &c__0, &c__0, &anorm, &ssfmin, &i__1, &c__1, &e[l], n, + info); + } + +/* Choose between QL and QR iteration */ + + if ((r__1 = d__[lend], dabs(r__1)) < (r__2 = d__[l], dabs(r__2))) { + lend = lsv; + l = lendsv; + } + + if (lend > l) { + +/* + QL Iteration + + Look for small subdiagonal element. +*/ + +L40: + if (l != lend) { + lendm1 = lend - 1; + i__1 = lendm1; + for (m = l; m <= i__1; ++m) { +/* Computing 2nd power */ + r__2 = (r__1 = e[m], dabs(r__1)); + tst = r__2 * r__2; + if (tst <= eps2 * (r__1 = d__[m], dabs(r__1)) * (r__2 = d__[m + + 1], dabs(r__2)) + safmin) { + goto L60; + } +/* L50: */ + } + } + + m = lend; + +L60: + if (m < lend) { + e[m] = 0.f; + } + p = d__[l]; + if (m == l) { + goto L80; + } + +/* + If remaining matrix is 2-by-2, use SLAE2 or SLAEV2 + to compute its eigensystem. +*/ + + if (m == l + 1) { + if (icompz > 0) { + slaev2_(&d__[l], &e[l], &d__[l + 1], &rt1, &rt2, &c__, &s); + work[l] = c__; + work[*n - 1 + l] = s; + slasr_("R", "V", "B", n, &c__2, &work[l], &work[*n - 1 + l], & + z__[l * z_dim1 + 1], ldz); + } else { + slae2_(&d__[l], &e[l], &d__[l + 1], &rt1, &rt2); + } + d__[l] = rt1; + d__[l + 1] = rt2; + e[l] = 0.f; + l += 2; + if (l <= lend) { + goto L40; + } + goto L140; + } + + if (jtot == nmaxit) { + goto L140; + } + ++jtot; + +/* Form shift. */ + + g = (d__[l + 1] - p) / (e[l] * 2.f); + r__ = slapy2_(&g, &c_b15); + g = d__[m] - p + e[l] / (g + r_sign(&r__, &g)); + + s = 1.f; + c__ = 1.f; + p = 0.f; + +/* Inner loop */ + + mm1 = m - 1; + i__1 = l; + for (i__ = mm1; i__ >= i__1; --i__) { + f = s * e[i__]; + b = c__ * e[i__]; + slartg_(&g, &f, &c__, &s, &r__); + if (i__ != m - 1) { + e[i__ + 1] = r__; + } + g = d__[i__ + 1] - p; + r__ = (d__[i__] - g) * s + c__ * 2.f * b; + p = s * r__; + d__[i__ + 1] = g + p; + g = c__ * r__ - b; + +/* If eigenvectors are desired, then save rotations. */ + + if (icompz > 0) { + work[i__] = c__; + work[*n - 1 + i__] = -s; + } + +/* L70: */ + } + +/* If eigenvectors are desired, then apply saved rotations. */ + + if (icompz > 0) { + mm = m - l + 1; + slasr_("R", "V", "B", n, &mm, &work[l], &work[*n - 1 + l], &z__[l + * z_dim1 + 1], ldz); + } + + d__[l] -= p; + e[l] = g; + goto L40; + +/* Eigenvalue found. */ + +L80: + d__[l] = p; + + ++l; + if (l <= lend) { + goto L40; + } + goto L140; + + } else { + +/* + QR Iteration + + Look for small superdiagonal element. +*/ + +L90: + if (l != lend) { + lendp1 = lend + 1; + i__1 = lendp1; + for (m = l; m >= i__1; --m) { +/* Computing 2nd power */ + r__2 = (r__1 = e[m - 1], dabs(r__1)); + tst = r__2 * r__2; + if (tst <= eps2 * (r__1 = d__[m], dabs(r__1)) * (r__2 = d__[m + - 1], dabs(r__2)) + safmin) { + goto L110; + } +/* L100: */ + } + } + + m = lend; + +L110: + if (m > lend) { + e[m - 1] = 0.f; + } + p = d__[l]; + if (m == l) { + goto L130; + } + +/* + If remaining matrix is 2-by-2, use SLAE2 or SLAEV2 + to compute its eigensystem. +*/ + + if (m == l - 1) { + if (icompz > 0) { + slaev2_(&d__[l - 1], &e[l - 1], &d__[l], &rt1, &rt2, &c__, &s) + ; + work[m] = c__; + work[*n - 1 + m] = s; + slasr_("R", "V", "F", n, &c__2, &work[m], &work[*n - 1 + m], & + z__[(l - 1) * z_dim1 + 1], ldz); + } else { + slae2_(&d__[l - 1], &e[l - 1], &d__[l], &rt1, &rt2); + } + d__[l - 1] = rt1; + d__[l] = rt2; + e[l - 1] = 0.f; + l += -2; + if (l >= lend) { + goto L90; + } + goto L140; + } + + if (jtot == nmaxit) { + goto L140; + } + ++jtot; + +/* Form shift. */ + + g = (d__[l - 1] - p) / (e[l - 1] * 2.f); + r__ = slapy2_(&g, &c_b15); + g = d__[m] - p + e[l - 1] / (g + r_sign(&r__, &g)); + + s = 1.f; + c__ = 1.f; + p = 0.f; + +/* Inner loop */ + + lm1 = l - 1; + i__1 = lm1; + for (i__ = m; i__ <= i__1; ++i__) { + f = s * e[i__]; + b = c__ * e[i__]; + slartg_(&g, &f, &c__, &s, &r__); + if (i__ != m) { + e[i__ - 1] = r__; + } + g = d__[i__] - p; + r__ = (d__[i__ + 1] - g) * s + c__ * 2.f * b; + p = s * r__; + d__[i__] = g + p; + g = c__ * r__ - b; + +/* If eigenvectors are desired, then save rotations. */ + + if (icompz > 0) { + work[i__] = c__; + work[*n - 1 + i__] = s; + } + +/* L120: */ + } + +/* If eigenvectors are desired, then apply saved rotations. */ + + if (icompz > 0) { + mm = l - m + 1; + slasr_("R", "V", "F", n, &mm, &work[m], &work[*n - 1 + m], &z__[m + * z_dim1 + 1], ldz); + } + + d__[l] -= p; + e[lm1] = g; + goto L90; + +/* Eigenvalue found. */ + +L130: + d__[l] = p; + + --l; + if (l >= lend) { + goto L90; + } + goto L140; + + } + +/* Undo scaling if necessary */ + +L140: + if (iscale == 1) { + i__1 = lendsv - lsv + 1; + slascl_("G", &c__0, &c__0, &ssfmax, &anorm, &i__1, &c__1, &d__[lsv], + n, info); + i__1 = lendsv - lsv; + slascl_("G", &c__0, &c__0, &ssfmax, &anorm, &i__1, &c__1, &e[lsv], n, + info); + } else if (iscale == 2) { + i__1 = lendsv - lsv + 1; + slascl_("G", &c__0, &c__0, &ssfmin, &anorm, &i__1, &c__1, &d__[lsv], + n, info); + i__1 = lendsv - lsv; + slascl_("G", &c__0, &c__0, &ssfmin, &anorm, &i__1, &c__1, &e[lsv], n, + info); + } + +/* + Check for no convergence to an eigenvalue after a total + of N*MAXIT iterations. +*/ + + if (jtot < nmaxit) { + goto L10; + } + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + if (e[i__] != 0.f) { + ++(*info); + } +/* L150: */ + } + goto L190; + +/* Order eigenvalues and eigenvectors. */ + +L160: + if (icompz == 0) { + +/* Use Quick Sort */ + + slasrt_("I", n, &d__[1], info); + + } else { + +/* Use Selection Sort to minimize swaps of eigenvectors */ + + i__1 = *n; + for (ii = 2; ii <= i__1; ++ii) { + i__ = ii - 1; + k = i__; + p = d__[i__]; + i__2 = *n; + for (j = ii; j <= i__2; ++j) { + if (d__[j] < p) { + k = j; + p = d__[j]; + } +/* L170: */ + } + if (k != i__) { + d__[k] = d__[i__]; + d__[i__] = p; + sswap_(n, &z__[i__ * z_dim1 + 1], &c__1, &z__[k * z_dim1 + 1], + &c__1); + } +/* L180: */ + } + } + +L190: + return 0; + +/* End of SSTEQR */ + +} /* ssteqr_ */ + +/* Subroutine */ int ssterf_(integer *n, real *d__, real *e, integer *info) +{ + /* System generated locals */ + integer i__1; + real r__1, r__2, r__3; + + /* Builtin functions */ + double sqrt(doublereal), r_sign(real *, real *); + + /* Local variables */ + static real c__; + static integer i__, l, m; + static real p, r__, s; + static integer l1; + static real bb, rt1, rt2, eps, rte; + static integer lsv; + static real eps2, oldc; + static integer lend, jtot; + extern /* Subroutine */ int slae2_(real *, real *, real *, real *, real *) + ; + static real gamma, alpha, sigma, anorm; + extern doublereal slapy2_(real *, real *); + static integer iscale; + static real oldgam; + extern doublereal slamch_(char *); + static real safmin; + extern /* Subroutine */ int xerbla_(char *, integer *); + static real safmax; + extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *, + real *, integer *, integer *, real *, integer *, integer *); + static integer lendsv; + static real ssfmin; + static integer nmaxit; + static real ssfmax; + extern doublereal slanst_(char *, integer *, real *, real *); + extern /* Subroutine */ int slasrt_(char *, integer *, real *, integer *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SSTERF computes all eigenvalues of a symmetric tridiagonal matrix + using the Pal-Walker-Kahan variant of the QL or QR algorithm. + + Arguments + ========= + + N (input) INTEGER + The order of the matrix. N >= 0. + + D (input/output) REAL array, dimension (N) + On entry, the n diagonal elements of the tridiagonal matrix. + On exit, if INFO = 0, the eigenvalues in ascending order. + + E (input/output) REAL array, dimension (N-1) + On entry, the (n-1) subdiagonal elements of the tridiagonal + matrix. + On exit, E has been destroyed. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + > 0: the algorithm failed to find all of the eigenvalues in + a total of 30*N iterations; if INFO = i, then i + elements of E have not converged to zero. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + --e; + --d__; + + /* Function Body */ + *info = 0; + +/* Quick return if possible */ + + if (*n < 0) { + *info = -1; + i__1 = -(*info); + xerbla_("SSTERF", &i__1); + return 0; + } + if (*n <= 1) { + return 0; + } + +/* Determine the unit roundoff for this environment. */ + + eps = slamch_("E"); +/* Computing 2nd power */ + r__1 = eps; + eps2 = r__1 * r__1; + safmin = slamch_("S"); + safmax = 1.f / safmin; + ssfmax = sqrt(safmax) / 3.f; + ssfmin = sqrt(safmin) / eps2; + +/* Compute the eigenvalues of the tridiagonal matrix. */ + + nmaxit = *n * 30; + sigma = 0.f; + jtot = 0; + +/* + Determine where the matrix splits and choose QL or QR iteration + for each block, according to whether top or bottom diagonal + element is smaller. +*/ + + l1 = 1; + +L10: + if (l1 > *n) { + goto L170; + } + if (l1 > 1) { + e[l1 - 1] = 0.f; + } + i__1 = *n - 1; + for (m = l1; m <= i__1; ++m) { + if ((r__3 = e[m], dabs(r__3)) <= sqrt((r__1 = d__[m], dabs(r__1))) * + sqrt((r__2 = d__[m + 1], dabs(r__2))) * eps) { + e[m] = 0.f; + goto L30; + } +/* L20: */ + } + m = *n; + +L30: + l = l1; + lsv = l; + lend = m; + lendsv = lend; + l1 = m + 1; + if (lend == l) { + goto L10; + } + +/* Scale submatrix in rows and columns L to LEND */ + + i__1 = lend - l + 1; + anorm = slanst_("I", &i__1, &d__[l], &e[l]); + iscale = 0; + if (anorm > ssfmax) { + iscale = 1; + i__1 = lend - l + 1; + slascl_("G", &c__0, &c__0, &anorm, &ssfmax, &i__1, &c__1, &d__[l], n, + info); + i__1 = lend - l; + slascl_("G", &c__0, &c__0, &anorm, &ssfmax, &i__1, &c__1, &e[l], n, + info); + } else if (anorm < ssfmin) { + iscale = 2; + i__1 = lend - l + 1; + slascl_("G", &c__0, &c__0, &anorm, &ssfmin, &i__1, &c__1, &d__[l], n, + info); + i__1 = lend - l; + slascl_("G", &c__0, &c__0, &anorm, &ssfmin, &i__1, &c__1, &e[l], n, + info); + } + + i__1 = lend - 1; + for (i__ = l; i__ <= i__1; ++i__) { +/* Computing 2nd power */ + r__1 = e[i__]; + e[i__] = r__1 * r__1; +/* L40: */ + } + +/* Choose between QL and QR iteration */ + + if ((r__1 = d__[lend], dabs(r__1)) < (r__2 = d__[l], dabs(r__2))) { + lend = lsv; + l = lendsv; + } + + if (lend >= l) { + +/* + QL Iteration + + Look for small subdiagonal element. +*/ + +L50: + if (l != lend) { + i__1 = lend - 1; + for (m = l; m <= i__1; ++m) { + if ((r__2 = e[m], dabs(r__2)) <= eps2 * (r__1 = d__[m] * d__[ + m + 1], dabs(r__1))) { + goto L70; + } +/* L60: */ + } + } + m = lend; + +L70: + if (m < lend) { + e[m] = 0.f; + } + p = d__[l]; + if (m == l) { + goto L90; + } + +/* + If remaining matrix is 2 by 2, use SLAE2 to compute its + eigenvalues. +*/ + + if (m == l + 1) { + rte = sqrt(e[l]); + slae2_(&d__[l], &rte, &d__[l + 1], &rt1, &rt2); + d__[l] = rt1; + d__[l + 1] = rt2; + e[l] = 0.f; + l += 2; + if (l <= lend) { + goto L50; + } + goto L150; + } + + if (jtot == nmaxit) { + goto L150; + } + ++jtot; + +/* Form shift. */ + + rte = sqrt(e[l]); + sigma = (d__[l + 1] - p) / (rte * 2.f); + r__ = slapy2_(&sigma, &c_b15); + sigma = p - rte / (sigma + r_sign(&r__, &sigma)); + + c__ = 1.f; + s = 0.f; + gamma = d__[m] - sigma; + p = gamma * gamma; + +/* Inner loop */ + + i__1 = l; + for (i__ = m - 1; i__ >= i__1; --i__) { + bb = e[i__]; + r__ = p + bb; + if (i__ != m - 1) { + e[i__ + 1] = s * r__; + } + oldc = c__; + c__ = p / r__; + s = bb / r__; + oldgam = gamma; + alpha = d__[i__]; + gamma = c__ * (alpha - sigma) - s * oldgam; + d__[i__ + 1] = oldgam + (alpha - gamma); + if (c__ != 0.f) { + p = gamma * gamma / c__; + } else { + p = oldc * bb; + } +/* L80: */ + } + + e[l] = s * p; + d__[l] = sigma + gamma; + goto L50; + +/* Eigenvalue found. */ + +L90: + d__[l] = p; + + ++l; + if (l <= lend) { + goto L50; + } + goto L150; + + } else { + +/* + QR Iteration + + Look for small superdiagonal element. +*/ + +L100: + i__1 = lend + 1; + for (m = l; m >= i__1; --m) { + if ((r__2 = e[m - 1], dabs(r__2)) <= eps2 * (r__1 = d__[m] * d__[ + m - 1], dabs(r__1))) { + goto L120; + } +/* L110: */ + } + m = lend; + +L120: + if (m > lend) { + e[m - 1] = 0.f; + } + p = d__[l]; + if (m == l) { + goto L140; + } + +/* + If remaining matrix is 2 by 2, use SLAE2 to compute its + eigenvalues. +*/ + + if (m == l - 1) { + rte = sqrt(e[l - 1]); + slae2_(&d__[l], &rte, &d__[l - 1], &rt1, &rt2); + d__[l] = rt1; + d__[l - 1] = rt2; + e[l - 1] = 0.f; + l += -2; + if (l >= lend) { + goto L100; + } + goto L150; + } + + if (jtot == nmaxit) { + goto L150; + } + ++jtot; + +/* Form shift. */ + + rte = sqrt(e[l - 1]); + sigma = (d__[l - 1] - p) / (rte * 2.f); + r__ = slapy2_(&sigma, &c_b15); + sigma = p - rte / (sigma + r_sign(&r__, &sigma)); + + c__ = 1.f; + s = 0.f; + gamma = d__[m] - sigma; + p = gamma * gamma; + +/* Inner loop */ + + i__1 = l - 1; + for (i__ = m; i__ <= i__1; ++i__) { + bb = e[i__]; + r__ = p + bb; + if (i__ != m) { + e[i__ - 1] = s * r__; + } + oldc = c__; + c__ = p / r__; + s = bb / r__; + oldgam = gamma; + alpha = d__[i__ + 1]; + gamma = c__ * (alpha - sigma) - s * oldgam; + d__[i__] = oldgam + (alpha - gamma); + if (c__ != 0.f) { + p = gamma * gamma / c__; + } else { + p = oldc * bb; + } +/* L130: */ + } + + e[l - 1] = s * p; + d__[l] = sigma + gamma; + goto L100; + +/* Eigenvalue found. */ + +L140: + d__[l] = p; + + --l; + if (l >= lend) { + goto L100; + } + goto L150; + + } + +/* Undo scaling if necessary */ + +L150: + if (iscale == 1) { + i__1 = lendsv - lsv + 1; + slascl_("G", &c__0, &c__0, &ssfmax, &anorm, &i__1, &c__1, &d__[lsv], + n, info); + } + if (iscale == 2) { + i__1 = lendsv - lsv + 1; + slascl_("G", &c__0, &c__0, &ssfmin, &anorm, &i__1, &c__1, &d__[lsv], + n, info); + } + +/* + Check for no convergence to an eigenvalue after a total + of N*MAXIT iterations. +*/ + + if (jtot < nmaxit) { + goto L10; + } + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + if (e[i__] != 0.f) { + ++(*info); + } +/* L160: */ + } + goto L180; + +/* Sort eigenvalues in increasing order. */ + +L170: + slasrt_("I", n, &d__[1], info); + +L180: + return 0; + +/* End of SSTERF */ + +} /* ssterf_ */ + +/* Subroutine */ int ssyevd_(char *jobz, char *uplo, integer *n, real *a, + integer *lda, real *w, real *work, integer *lwork, integer *iwork, + integer *liwork, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + real r__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static real eps; + static integer inde; + static real anrm, rmin, rmax; + static integer lopt; + static real sigma; + extern logical lsame_(char *, char *); + static integer iinfo; + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *); + static integer lwmin, liopt; + static logical lower, wantz; + static integer indwk2, llwrk2, iscale; + extern doublereal slamch_(char *); + static real safmin; + extern /* Subroutine */ int xerbla_(char *, integer *); + static real bignum; + extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *, + real *, integer *, integer *, real *, integer *, integer *); + static integer indtau; + extern /* Subroutine */ int sstedc_(char *, integer *, real *, real *, + real *, integer *, real *, integer *, integer *, integer *, + integer *), slacpy_(char *, integer *, integer *, real *, + integer *, real *, integer *); + static integer indwrk, liwmin; + extern /* Subroutine */ int ssterf_(integer *, real *, real *, integer *); + extern doublereal slansy_(char *, char *, integer *, real *, integer *, + real *); + static integer llwork; + static real smlnum; + static logical lquery; + extern /* Subroutine */ int sormtr_(char *, char *, char *, integer *, + integer *, real *, integer *, real *, real *, integer *, real *, + integer *, integer *), ssytrd_(char *, + integer *, real *, integer *, real *, real *, real *, real *, + integer *, integer *); + + +/* + -- LAPACK driver routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SSYEVD computes all eigenvalues and, optionally, eigenvectors of a + real symmetric matrix A. If eigenvectors are desired, it uses a + divide and conquer algorithm. + + The divide and conquer algorithm makes very mild assumptions about + floating point arithmetic. It will work on machines with a guard + digit in add/subtract, or on those binary machines without guard + digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or + Cray-2. It could conceivably fail on hexadecimal or decimal machines + without guard digits, but we know of none. + + Because of large use of BLAS of level 3, SSYEVD needs N**2 more + workspace than SSYEVX. + + Arguments + ========= + + JOBZ (input) CHARACTER*1 + = 'N': Compute eigenvalues only; + = 'V': Compute eigenvalues and eigenvectors. + + UPLO (input) CHARACTER*1 + = 'U': Upper triangle of A is stored; + = 'L': Lower triangle of A is stored. + + N (input) INTEGER + The order of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA, N) + On entry, the symmetric matrix A. If UPLO = 'U', the + leading N-by-N upper triangular part of A contains the + upper triangular part of the matrix A. If UPLO = 'L', + the leading N-by-N lower triangular part of A contains + the lower triangular part of the matrix A. + On exit, if JOBZ = 'V', then if INFO = 0, A contains the + orthonormal eigenvectors of the matrix A. + If JOBZ = 'N', then on exit the lower triangle (if UPLO='L') + or the upper triangle (if UPLO='U') of A, including the + diagonal, is destroyed. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + W (output) REAL array, dimension (N) + If INFO = 0, the eigenvalues in ascending order. + + WORK (workspace/output) REAL array, + dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. + If N <= 1, LWORK must be at least 1. + If JOBZ = 'N' and N > 1, LWORK must be at least 2*N+1. + If JOBZ = 'V' and N > 1, LWORK must be at least + 1 + 6*N + 2*N**2. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + IWORK (workspace/output) INTEGER array, dimension (LIWORK) + On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK. + + LIWORK (input) INTEGER + The dimension of the array IWORK. + If N <= 1, LIWORK must be at least 1. + If JOBZ = 'N' and N > 1, LIWORK must be at least 1. + If JOBZ = 'V' and N > 1, LIWORK must be at least 3 + 5*N. + + If LIWORK = -1, then a workspace query is assumed; the + routine only calculates the optimal size of the IWORK array, + returns this value as the first entry of the IWORK array, and + no error message related to LIWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + > 0: if INFO = i, the algorithm failed to converge; i + off-diagonal elements of an intermediate tridiagonal + form did not converge to zero. + + Further Details + =============== + + Based on contributions by + Jeff Rutter, Computer Science Division, University of California + at Berkeley, USA + Modified by Francoise Tisseur, University of Tennessee. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --w; + --work; + --iwork; + + /* Function Body */ + wantz = lsame_(jobz, "V"); + lower = lsame_(uplo, "L"); + lquery = *lwork == -1 || *liwork == -1; + + *info = 0; + if (*n <= 1) { + liwmin = 1; + lwmin = 1; + lopt = lwmin; + liopt = liwmin; + } else { + if (wantz) { + liwmin = *n * 5 + 3; +/* Computing 2nd power */ + i__1 = *n; + lwmin = *n * 6 + 1 + (i__1 * i__1 << 1); + } else { + liwmin = 1; + lwmin = (*n << 1) + 1; + } + lopt = lwmin; + liopt = liwmin; + } + if (! (wantz || lsame_(jobz, "N"))) { + *info = -1; + } else if (! (lower || lsame_(uplo, "U"))) { + *info = -2; + } else if (*n < 0) { + *info = -3; + } else if (*lda < max(1,*n)) { + *info = -5; + } else if (*lwork < lwmin && ! lquery) { + *info = -8; + } else if (*liwork < liwmin && ! lquery) { + *info = -10; + } + + if (*info == 0) { + work[1] = (real) lopt; + iwork[1] = liopt; + } + + if (*info != 0) { + i__1 = -(*info); + xerbla_("SSYEVD", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + + if (*n == 1) { + w[1] = a[a_dim1 + 1]; + if (wantz) { + a[a_dim1 + 1] = 1.f; + } + return 0; + } + +/* Get machine constants. */ + + safmin = slamch_("Safe minimum"); + eps = slamch_("Precision"); + smlnum = safmin / eps; + bignum = 1.f / smlnum; + rmin = sqrt(smlnum); + rmax = sqrt(bignum); + +/* Scale matrix to allowable range, if necessary. */ + + anrm = slansy_("M", uplo, n, &a[a_offset], lda, &work[1]); + iscale = 0; + if (anrm > 0.f && anrm < rmin) { + iscale = 1; + sigma = rmin / anrm; + } else if (anrm > rmax) { + iscale = 1; + sigma = rmax / anrm; + } + if (iscale == 1) { + slascl_(uplo, &c__0, &c__0, &c_b15, &sigma, n, n, &a[a_offset], lda, + info); + } + +/* Call SSYTRD to reduce symmetric matrix to tridiagonal form. */ + + inde = 1; + indtau = inde + *n; + indwrk = indtau + *n; + llwork = *lwork - indwrk + 1; + indwk2 = indwrk + *n * *n; + llwrk2 = *lwork - indwk2 + 1; + + ssytrd_(uplo, n, &a[a_offset], lda, &w[1], &work[inde], &work[indtau], & + work[indwrk], &llwork, &iinfo); + lopt = (*n << 1) + work[indwrk]; + +/* + For eigenvalues only, call SSTERF. For eigenvectors, first call + SSTEDC to generate the eigenvector matrix, WORK(INDWRK), of the + tridiagonal matrix, then call SORMTR to multiply it by the + Householder transformations stored in A. +*/ + + if (! wantz) { + ssterf_(n, &w[1], &work[inde], info); + } else { + sstedc_("I", n, &w[1], &work[inde], &work[indwrk], n, &work[indwk2], & + llwrk2, &iwork[1], liwork, info); + sormtr_("L", uplo, "N", n, n, &a[a_offset], lda, &work[indtau], &work[ + indwrk], n, &work[indwk2], &llwrk2, &iinfo); + slacpy_("A", n, n, &work[indwrk], n, &a[a_offset], lda); +/* + Computing MAX + Computing 2nd power +*/ + i__3 = *n; + i__1 = lopt, i__2 = *n * 6 + 1 + (i__3 * i__3 << 1); + lopt = max(i__1,i__2); + } + +/* If matrix was scaled, then rescale eigenvalues appropriately. */ + + if (iscale == 1) { + r__1 = 1.f / sigma; + sscal_(n, &r__1, &w[1], &c__1); + } + + work[1] = (real) lopt; + iwork[1] = liopt; + + return 0; + +/* End of SSYEVD */ + +} /* ssyevd_ */ + +/* Subroutine */ int ssytd2_(char *uplo, integer *n, real *a, integer *lda, + real *d__, real *e, real *tau, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + + /* Local variables */ + static integer i__; + static real taui; + extern doublereal sdot_(integer *, real *, integer *, real *, integer *); + extern /* Subroutine */ int ssyr2_(char *, integer *, real *, real *, + integer *, real *, integer *, real *, integer *); + static real alpha; + extern logical lsame_(char *, char *); + static logical upper; + extern /* Subroutine */ int saxpy_(integer *, real *, real *, integer *, + real *, integer *), ssymv_(char *, integer *, real *, real *, + integer *, real *, integer *, real *, real *, integer *), + xerbla_(char *, integer *), slarfg_(integer *, real *, + real *, integer *, real *); + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + October 31, 1992 + + + Purpose + ======= + + SSYTD2 reduces a real symmetric matrix A to symmetric tridiagonal + form T by an orthogonal similarity transformation: Q' * A * Q = T. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + Specifies whether the upper or lower triangular part of the + symmetric matrix A is stored: + = 'U': Upper triangular + = 'L': Lower triangular + + N (input) INTEGER + The order of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the symmetric matrix A. If UPLO = 'U', the leading + n-by-n upper triangular part of A contains the upper + triangular part of the matrix A, and the strictly lower + triangular part of A is not referenced. If UPLO = 'L', the + leading n-by-n lower triangular part of A contains the lower + triangular part of the matrix A, and the strictly upper + triangular part of A is not referenced. + On exit, if UPLO = 'U', the diagonal and first superdiagonal + of A are overwritten by the corresponding elements of the + tridiagonal matrix T, and the elements above the first + superdiagonal, with the array TAU, represent the orthogonal + matrix Q as a product of elementary reflectors; if UPLO + = 'L', the diagonal and first subdiagonal of A are over- + written by the corresponding elements of the tridiagonal + matrix T, and the elements below the first subdiagonal, with + the array TAU, represent the orthogonal matrix Q as a product + of elementary reflectors. See Further Details. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + D (output) REAL array, dimension (N) + The diagonal elements of the tridiagonal matrix T: + D(i) = A(i,i). + + E (output) REAL array, dimension (N-1) + The off-diagonal elements of the tridiagonal matrix T: + E(i) = A(i,i+1) if UPLO = 'U', E(i) = A(i+1,i) if UPLO = 'L'. + + TAU (output) REAL array, dimension (N-1) + The scalar factors of the elementary reflectors (see Further + Details). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value. + + Further Details + =============== + + If UPLO = 'U', the matrix Q is represented as a product of elementary + reflectors + + Q = H(n-1) . . . H(2) H(1). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(i+1:n) = 0 and v(i) = 1; v(1:i-1) is stored on exit in + A(1:i-1,i+1), and tau in TAU(i). + + If UPLO = 'L', the matrix Q is represented as a product of elementary + reflectors + + Q = H(1) H(2) . . . H(n-1). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(1:i) = 0 and v(i+1) = 1; v(i+2:n) is stored on exit in A(i+2:n,i), + and tau in TAU(i). + + The contents of A on exit are illustrated by the following examples + with n = 5: + + if UPLO = 'U': if UPLO = 'L': + + ( d e v2 v3 v4 ) ( d ) + ( d e v3 v4 ) ( e d ) + ( d e v4 ) ( v1 e d ) + ( d e ) ( v1 v2 e d ) + ( d ) ( v1 v2 v3 e d ) + + where d and e denote diagonal and off-diagonal elements of T, and vi + denotes an element of the vector defining H(i). + + ===================================================================== + + + Test the input parameters +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --d__; + --e; + --tau; + + /* Function Body */ + *info = 0; + upper = lsame_(uplo, "U"); + if (! upper && ! lsame_(uplo, "L")) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*n)) { + *info = -4; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("SSYTD2", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n <= 0) { + return 0; + } + + if (upper) { + +/* Reduce the upper triangle of A */ + + for (i__ = *n - 1; i__ >= 1; --i__) { + +/* + Generate elementary reflector H(i) = I - tau * v * v' + to annihilate A(1:i-1,i+1) +*/ + + slarfg_(&i__, &a[i__ + (i__ + 1) * a_dim1], &a[(i__ + 1) * a_dim1 + + 1], &c__1, &taui); + e[i__] = a[i__ + (i__ + 1) * a_dim1]; + + if (taui != 0.f) { + +/* Apply H(i) from both sides to A(1:i,1:i) */ + + a[i__ + (i__ + 1) * a_dim1] = 1.f; + +/* Compute x := tau * A * v storing x in TAU(1:i) */ + + ssymv_(uplo, &i__, &taui, &a[a_offset], lda, &a[(i__ + 1) * + a_dim1 + 1], &c__1, &c_b29, &tau[1], &c__1) + ; + +/* Compute w := x - 1/2 * tau * (x'*v) * v */ + + alpha = taui * -.5f * sdot_(&i__, &tau[1], &c__1, &a[(i__ + 1) + * a_dim1 + 1], &c__1); + saxpy_(&i__, &alpha, &a[(i__ + 1) * a_dim1 + 1], &c__1, &tau[ + 1], &c__1); + +/* + Apply the transformation as a rank-2 update: + A := A - v * w' - w * v' +*/ + + ssyr2_(uplo, &i__, &c_b151, &a[(i__ + 1) * a_dim1 + 1], &c__1, + &tau[1], &c__1, &a[a_offset], lda); + + a[i__ + (i__ + 1) * a_dim1] = e[i__]; + } + d__[i__ + 1] = a[i__ + 1 + (i__ + 1) * a_dim1]; + tau[i__] = taui; +/* L10: */ + } + d__[1] = a[a_dim1 + 1]; + } else { + +/* Reduce the lower triangle of A */ + + i__1 = *n - 1; + for (i__ = 1; i__ <= i__1; ++i__) { + +/* + Generate elementary reflector H(i) = I - tau * v * v' + to annihilate A(i+2:n,i) +*/ + + i__2 = *n - i__; +/* Computing MIN */ + i__3 = i__ + 2; + slarfg_(&i__2, &a[i__ + 1 + i__ * a_dim1], &a[min(i__3,*n) + i__ * + a_dim1], &c__1, &taui); + e[i__] = a[i__ + 1 + i__ * a_dim1]; + + if (taui != 0.f) { + +/* Apply H(i) from both sides to A(i+1:n,i+1:n) */ + + a[i__ + 1 + i__ * a_dim1] = 1.f; + +/* Compute x := tau * A * v storing y in TAU(i:n-1) */ + + i__2 = *n - i__; + ssymv_(uplo, &i__2, &taui, &a[i__ + 1 + (i__ + 1) * a_dim1], + lda, &a[i__ + 1 + i__ * a_dim1], &c__1, &c_b29, &tau[ + i__], &c__1); + +/* Compute w := x - 1/2 * tau * (x'*v) * v */ + + i__2 = *n - i__; + alpha = taui * -.5f * sdot_(&i__2, &tau[i__], &c__1, &a[i__ + + 1 + i__ * a_dim1], &c__1); + i__2 = *n - i__; + saxpy_(&i__2, &alpha, &a[i__ + 1 + i__ * a_dim1], &c__1, &tau[ + i__], &c__1); + +/* + Apply the transformation as a rank-2 update: + A := A - v * w' - w * v' +*/ + + i__2 = *n - i__; + ssyr2_(uplo, &i__2, &c_b151, &a[i__ + 1 + i__ * a_dim1], & + c__1, &tau[i__], &c__1, &a[i__ + 1 + (i__ + 1) * + a_dim1], lda); + + a[i__ + 1 + i__ * a_dim1] = e[i__]; + } + d__[i__] = a[i__ + i__ * a_dim1]; + tau[i__] = taui; +/* L20: */ + } + d__[*n] = a[*n + *n * a_dim1]; + } + + return 0; + +/* End of SSYTD2 */ + +} /* ssytd2_ */ + +/* Subroutine */ int ssytrd_(char *uplo, integer *n, real *a, integer *lda, + real *d__, real *e, real *tau, real *work, integer *lwork, integer * + info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2, i__3; + + /* Local variables */ + static integer i__, j, nb, kk, nx, iws; + extern logical lsame_(char *, char *); + static integer nbmin, iinfo; + static logical upper; + extern /* Subroutine */ int ssytd2_(char *, integer *, real *, integer *, + real *, real *, real *, integer *), ssyr2k_(char *, char * + , integer *, integer *, real *, real *, integer *, real *, + integer *, real *, real *, integer *), xerbla_( + char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + extern /* Subroutine */ int slatrd_(char *, integer *, integer *, real *, + integer *, real *, real *, real *, integer *); + static integer ldwork, lwkopt; + static logical lquery; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + SSYTRD reduces a real symmetric matrix A to real symmetric + tridiagonal form T by an orthogonal similarity transformation: + Q**T * A * Q = T. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + = 'U': Upper triangle of A is stored; + = 'L': Lower triangle of A is stored. + + N (input) INTEGER + The order of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the symmetric matrix A. If UPLO = 'U', the leading + N-by-N upper triangular part of A contains the upper + triangular part of the matrix A, and the strictly lower + triangular part of A is not referenced. If UPLO = 'L', the + leading N-by-N lower triangular part of A contains the lower + triangular part of the matrix A, and the strictly upper + triangular part of A is not referenced. + On exit, if UPLO = 'U', the diagonal and first superdiagonal + of A are overwritten by the corresponding elements of the + tridiagonal matrix T, and the elements above the first + superdiagonal, with the array TAU, represent the orthogonal + matrix Q as a product of elementary reflectors; if UPLO + = 'L', the diagonal and first subdiagonal of A are over- + written by the corresponding elements of the tridiagonal + matrix T, and the elements below the first subdiagonal, with + the array TAU, represent the orthogonal matrix Q as a product + of elementary reflectors. See Further Details. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + D (output) REAL array, dimension (N) + The diagonal elements of the tridiagonal matrix T: + D(i) = A(i,i). + + E (output) REAL array, dimension (N-1) + The off-diagonal elements of the tridiagonal matrix T: + E(i) = A(i,i+1) if UPLO = 'U', E(i) = A(i+1,i) if UPLO = 'L'. + + TAU (output) REAL array, dimension (N-1) + The scalar factors of the elementary reflectors (see Further + Details). + + WORK (workspace/output) REAL array, dimension (LWORK) + On exit, if INFO = 0, WORK(1) returns the optimal LWORK. + + LWORK (input) INTEGER + The dimension of the array WORK. LWORK >= 1. + For optimum performance LWORK >= N*NB, where NB is the + optimal blocksize. + + If LWORK = -1, then a workspace query is assumed; the routine + only calculates the optimal size of the WORK array, returns + this value as the first entry of the WORK array, and no error + message related to LWORK is issued by XERBLA. + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + Further Details + =============== + + If UPLO = 'U', the matrix Q is represented as a product of elementary + reflectors + + Q = H(n-1) . . . H(2) H(1). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(i+1:n) = 0 and v(i) = 1; v(1:i-1) is stored on exit in + A(1:i-1,i+1), and tau in TAU(i). + + If UPLO = 'L', the matrix Q is represented as a product of elementary + reflectors + + Q = H(1) H(2) . . . H(n-1). + + Each H(i) has the form + + H(i) = I - tau * v * v' + + where tau is a real scalar, and v is a real vector with + v(1:i) = 0 and v(i+1) = 1; v(i+2:n) is stored on exit in A(i+2:n,i), + and tau in TAU(i). + + The contents of A on exit are illustrated by the following examples + with n = 5: + + if UPLO = 'U': if UPLO = 'L': + + ( d e v2 v3 v4 ) ( d ) + ( d e v3 v4 ) ( e d ) + ( d e v4 ) ( v1 e d ) + ( d e ) ( v1 v2 e d ) + ( d ) ( v1 v2 v3 e d ) + + where d and e denote diagonal and off-diagonal elements of T, and vi + denotes an element of the vector defining H(i). + + ===================================================================== + + + Test the input parameters +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + --d__; + --e; + --tau; + --work; + + /* Function Body */ + *info = 0; + upper = lsame_(uplo, "U"); + lquery = *lwork == -1; + if (! upper && ! lsame_(uplo, "L")) { + *info = -1; + } else if (*n < 0) { + *info = -2; + } else if (*lda < max(1,*n)) { + *info = -4; + } else if (*lwork < 1 && ! lquery) { + *info = -9; + } + + if (*info == 0) { + +/* Determine the block size. */ + + nb = ilaenv_(&c__1, "SSYTRD", uplo, n, &c_n1, &c_n1, &c_n1, (ftnlen)6, + (ftnlen)1); + lwkopt = *n * nb; + work[1] = (real) lwkopt; + } + + if (*info != 0) { + i__1 = -(*info); + xerbla_("SSYTRD", &i__1); + return 0; + } else if (lquery) { + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + work[1] = 1.f; + return 0; + } + + nx = *n; + iws = 1; + if (nb > 1 && nb < *n) { + +/* + Determine when to cross over from blocked to unblocked code + (last block is always handled by unblocked code). + + Computing MAX +*/ + i__1 = nb, i__2 = ilaenv_(&c__3, "SSYTRD", uplo, n, &c_n1, &c_n1, & + c_n1, (ftnlen)6, (ftnlen)1); + nx = max(i__1,i__2); + if (nx < *n) { + +/* Determine if workspace is large enough for blocked code. */ + + ldwork = *n; + iws = ldwork * nb; + if (*lwork < iws) { + +/* + Not enough workspace to use optimal NB: determine the + minimum value of NB, and reduce NB or force use of + unblocked code by setting NX = N. + + Computing MAX +*/ + i__1 = *lwork / ldwork; + nb = max(i__1,1); + nbmin = ilaenv_(&c__2, "SSYTRD", uplo, n, &c_n1, &c_n1, &c_n1, + (ftnlen)6, (ftnlen)1); + if (nb < nbmin) { + nx = *n; + } + } + } else { + nx = *n; + } + } else { + nb = 1; + } + + if (upper) { + +/* + Reduce the upper triangle of A. + Columns 1:kk are handled by the unblocked method. +*/ + + kk = *n - (*n - nx + nb - 1) / nb * nb; + i__1 = kk + 1; + i__2 = -nb; + for (i__ = *n - nb + 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += + i__2) { + +/* + Reduce columns i:i+nb-1 to tridiagonal form and form the + matrix W which is needed to update the unreduced part of + the matrix +*/ + + i__3 = i__ + nb - 1; + slatrd_(uplo, &i__3, &nb, &a[a_offset], lda, &e[1], &tau[1], & + work[1], &ldwork); + +/* + Update the unreduced submatrix A(1:i-1,1:i-1), using an + update of the form: A := A - V*W' - W*V' +*/ + + i__3 = i__ - 1; + ssyr2k_(uplo, "No transpose", &i__3, &nb, &c_b151, &a[i__ * + a_dim1 + 1], lda, &work[1], &ldwork, &c_b15, &a[a_offset], + lda); + +/* + Copy superdiagonal elements back into A, and diagonal + elements into D +*/ + + i__3 = i__ + nb - 1; + for (j = i__; j <= i__3; ++j) { + a[j - 1 + j * a_dim1] = e[j - 1]; + d__[j] = a[j + j * a_dim1]; +/* L10: */ + } +/* L20: */ + } + +/* Use unblocked code to reduce the last or only block */ + + ssytd2_(uplo, &kk, &a[a_offset], lda, &d__[1], &e[1], &tau[1], &iinfo); + } else { + +/* Reduce the lower triangle of A */ + + i__2 = *n - nx; + i__1 = nb; + for (i__ = 1; i__1 < 0 ? i__ >= i__2 : i__ <= i__2; i__ += i__1) { + +/* + Reduce columns i:i+nb-1 to tridiagonal form and form the + matrix W which is needed to update the unreduced part of + the matrix +*/ + + i__3 = *n - i__ + 1; + slatrd_(uplo, &i__3, &nb, &a[i__ + i__ * a_dim1], lda, &e[i__], & + tau[i__], &work[1], &ldwork); + +/* + Update the unreduced submatrix A(i+ib:n,i+ib:n), using + an update of the form: A := A - V*W' - W*V' +*/ + + i__3 = *n - i__ - nb + 1; + ssyr2k_(uplo, "No transpose", &i__3, &nb, &c_b151, &a[i__ + nb + + i__ * a_dim1], lda, &work[nb + 1], &ldwork, &c_b15, &a[ + i__ + nb + (i__ + nb) * a_dim1], lda); + +/* + Copy subdiagonal elements back into A, and diagonal + elements into D +*/ + + i__3 = i__ + nb - 1; + for (j = i__; j <= i__3; ++j) { + a[j + 1 + j * a_dim1] = e[j]; + d__[j] = a[j + j * a_dim1]; +/* L30: */ + } +/* L40: */ + } + +/* Use unblocked code to reduce the last or only block */ + + i__1 = *n - i__ + 1; + ssytd2_(uplo, &i__1, &a[i__ + i__ * a_dim1], lda, &d__[i__], &e[i__], + &tau[i__], &iinfo); + } + + work[1] = (real) lwkopt; + return 0; + +/* End of SSYTRD */ + +} /* ssytrd_ */ + +/* Subroutine */ int strevc_(char *side, char *howmny, logical *select, + integer *n, real *t, integer *ldt, real *vl, integer *ldvl, real *vr, + integer *ldvr, integer *mm, integer *m, real *work, integer *info) +{ + /* System generated locals */ + integer t_dim1, t_offset, vl_dim1, vl_offset, vr_dim1, vr_offset, i__1, + i__2, i__3; + real r__1, r__2, r__3, r__4; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + static integer i__, j, k; + static real x[4] /* was [2][2] */; + static integer j1, j2, n2, ii, ki, ip, is; + static real wi, wr, rec, ulp, beta, emax; + static logical pair, allv; + static integer ierr; + static real unfl, ovfl, smin; + extern doublereal sdot_(integer *, real *, integer *, real *, integer *); + static logical over; + static real vmax; + static integer jnxt; + static real scale; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *); + static real remax; + static logical leftv; + extern /* Subroutine */ int sgemv_(char *, integer *, integer *, real *, + real *, integer *, real *, integer *, real *, real *, integer *); + static logical bothv; + static real vcrit; + static logical somev; + extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, + integer *); + static real xnorm; + extern /* Subroutine */ int saxpy_(integer *, real *, real *, integer *, + real *, integer *), slaln2_(logical *, integer *, integer *, real + *, real *, real *, integer *, real *, real *, real *, integer *, + real *, real *, real *, integer *, real *, real *, integer *), + slabad_(real *, real *); + extern doublereal slamch_(char *); + extern /* Subroutine */ int xerbla_(char *, integer *); + static real bignum; + extern integer isamax_(integer *, real *, integer *); + static logical rightv; + static real smlnum; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + June 30, 1999 + + + Purpose + ======= + + STREVC computes some or all of the right and/or left eigenvectors of + a real upper quasi-triangular matrix T. + + The right eigenvector x and the left eigenvector y of T corresponding + to an eigenvalue w are defined by: + + T*x = w*x, y'*T = w*y' + + where y' denotes the conjugate transpose of the vector y. + + If all eigenvectors are requested, the routine may either return the + matrices X and/or Y of right or left eigenvectors of T, or the + products Q*X and/or Q*Y, where Q is an input orthogonal + matrix. If T was obtained from the real-Schur factorization of an + original matrix A = Q*T*Q', then Q*X and Q*Y are the matrices of + right or left eigenvectors of A. + + T must be in Schur canonical form (as returned by SHSEQR), that is, + block upper triangular with 1-by-1 and 2-by-2 diagonal blocks; each + 2-by-2 diagonal block has its diagonal elements equal and its + off-diagonal elements of opposite sign. Corresponding to each 2-by-2 + diagonal block is a complex conjugate pair of eigenvalues and + eigenvectors; only one eigenvector of the pair is computed, namely + the one corresponding to the eigenvalue with positive imaginary part. + + Arguments + ========= + + SIDE (input) CHARACTER*1 + = 'R': compute right eigenvectors only; + = 'L': compute left eigenvectors only; + = 'B': compute both right and left eigenvectors. + + HOWMNY (input) CHARACTER*1 + = 'A': compute all right and/or left eigenvectors; + = 'B': compute all right and/or left eigenvectors, + and backtransform them using the input matrices + supplied in VR and/or VL; + = 'S': compute selected right and/or left eigenvectors, + specified by the logical array SELECT. + + SELECT (input/output) LOGICAL array, dimension (N) + If HOWMNY = 'S', SELECT specifies the eigenvectors to be + computed. + If HOWMNY = 'A' or 'B', SELECT is not referenced. + To select the real eigenvector corresponding to a real + eigenvalue w(j), SELECT(j) must be set to .TRUE.. To select + the complex eigenvector corresponding to a complex conjugate + pair w(j) and w(j+1), either SELECT(j) or SELECT(j+1) must be + set to .TRUE.; then on exit SELECT(j) is .TRUE. and + SELECT(j+1) is .FALSE.. + + N (input) INTEGER + The order of the matrix T. N >= 0. + + T (input) REAL array, dimension (LDT,N) + The upper quasi-triangular matrix T in Schur canonical form. + + LDT (input) INTEGER + The leading dimension of the array T. LDT >= max(1,N). + + VL (input/output) REAL array, dimension (LDVL,MM) + On entry, if SIDE = 'L' or 'B' and HOWMNY = 'B', VL must + contain an N-by-N matrix Q (usually the orthogonal matrix Q + of Schur vectors returned by SHSEQR). + On exit, if SIDE = 'L' or 'B', VL contains: + if HOWMNY = 'A', the matrix Y of left eigenvectors of T; + VL has the same quasi-lower triangular form + as T'. If T(i,i) is a real eigenvalue, then + the i-th column VL(i) of VL is its + corresponding eigenvector. If T(i:i+1,i:i+1) + is a 2-by-2 block whose eigenvalues are + complex-conjugate eigenvalues of T, then + VL(i)+sqrt(-1)*VL(i+1) is the complex + eigenvector corresponding to the eigenvalue + with positive real part. + if HOWMNY = 'B', the matrix Q*Y; + if HOWMNY = 'S', the left eigenvectors of T specified by + SELECT, stored consecutively in the columns + of VL, in the same order as their + eigenvalues. + A complex eigenvector corresponding to a complex eigenvalue + is stored in two consecutive columns, the first holding the + real part, and the second the imaginary part. + If SIDE = 'R', VL is not referenced. + + LDVL (input) INTEGER + The leading dimension of the array VL. LDVL >= max(1,N) if + SIDE = 'L' or 'B'; LDVL >= 1 otherwise. + + VR (input/output) REAL array, dimension (LDVR,MM) + On entry, if SIDE = 'R' or 'B' and HOWMNY = 'B', VR must + contain an N-by-N matrix Q (usually the orthogonal matrix Q + of Schur vectors returned by SHSEQR). + On exit, if SIDE = 'R' or 'B', VR contains: + if HOWMNY = 'A', the matrix X of right eigenvectors of T; + VR has the same quasi-upper triangular form + as T. If T(i,i) is a real eigenvalue, then + the i-th column VR(i) of VR is its + corresponding eigenvector. If T(i:i+1,i:i+1) + is a 2-by-2 block whose eigenvalues are + complex-conjugate eigenvalues of T, then + VR(i)+sqrt(-1)*VR(i+1) is the complex + eigenvector corresponding to the eigenvalue + with positive real part. + if HOWMNY = 'B', the matrix Q*X; + if HOWMNY = 'S', the right eigenvectors of T specified by + SELECT, stored consecutively in the columns + of VR, in the same order as their + eigenvalues. + A complex eigenvector corresponding to a complex eigenvalue + is stored in two consecutive columns, the first holding the + real part and the second the imaginary part. + If SIDE = 'L', VR is not referenced. + + LDVR (input) INTEGER + The leading dimension of the array VR. LDVR >= max(1,N) if + SIDE = 'R' or 'B'; LDVR >= 1 otherwise. + + MM (input) INTEGER + The number of columns in the arrays VL and/or VR. MM >= M. + + M (output) INTEGER + The number of columns in the arrays VL and/or VR actually + used to store the eigenvectors. + If HOWMNY = 'A' or 'B', M is set to N. + Each selected real eigenvector occupies one column and each + selected complex eigenvector occupies two columns. + + WORK (workspace) REAL array, dimension (3*N) + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + + Further Details + =============== + + The algorithm used in this program is basically backward (forward) + substitution, with scaling to make the the code robust against + possible overflow. + + Each eigenvector is normalized so that the element of largest + magnitude has magnitude 1; here the magnitude of a complex number + (x,y) is taken to be |x| + |y|. + + ===================================================================== + + + Decode and test the input parameters +*/ + + /* Parameter adjustments */ + --select; + t_dim1 = *ldt; + t_offset = 1 + t_dim1; + t -= t_offset; + vl_dim1 = *ldvl; + vl_offset = 1 + vl_dim1; + vl -= vl_offset; + vr_dim1 = *ldvr; + vr_offset = 1 + vr_dim1; + vr -= vr_offset; + --work; + + /* Function Body */ + bothv = lsame_(side, "B"); + rightv = lsame_(side, "R") || bothv; + leftv = lsame_(side, "L") || bothv; + + allv = lsame_(howmny, "A"); + over = lsame_(howmny, "B"); + somev = lsame_(howmny, "S"); + + *info = 0; + if (! rightv && ! leftv) { + *info = -1; + } else if (! allv && ! over && ! somev) { + *info = -2; + } else if (*n < 0) { + *info = -4; + } else if (*ldt < max(1,*n)) { + *info = -6; + } else if (*ldvl < 1 || leftv && *ldvl < *n) { + *info = -8; + } else if (*ldvr < 1 || rightv && *ldvr < *n) { + *info = -10; + } else { + +/* + Set M to the number of columns required to store the selected + eigenvectors, standardize the array SELECT if necessary, and + test MM. +*/ + + if (somev) { + *m = 0; + pair = FALSE_; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + if (pair) { + pair = FALSE_; + select[j] = FALSE_; + } else { + if (j < *n) { + if (t[j + 1 + j * t_dim1] == 0.f) { + if (select[j]) { + ++(*m); + } + } else { + pair = TRUE_; + if (select[j] || select[j + 1]) { + select[j] = TRUE_; + *m += 2; + } + } + } else { + if (select[*n]) { + ++(*m); + } + } + } +/* L10: */ + } + } else { + *m = *n; + } + + if (*mm < *m) { + *info = -11; + } + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("STREVC", &i__1); + return 0; + } + +/* Quick return if possible. */ + + if (*n == 0) { + return 0; + } + +/* Set the constants to control overflow. */ + + unfl = slamch_("Safe minimum"); + ovfl = 1.f / unfl; + slabad_(&unfl, &ovfl); + ulp = slamch_("Precision"); + smlnum = unfl * (*n / ulp); + bignum = (1.f - ulp) / smlnum; + +/* + Compute 1-norm of each column of strictly upper triangular + part of T to control overflow in triangular solver. +*/ + + work[1] = 0.f; + i__1 = *n; + for (j = 2; j <= i__1; ++j) { + work[j] = 0.f; + i__2 = j - 1; + for (i__ = 1; i__ <= i__2; ++i__) { + work[j] += (r__1 = t[i__ + j * t_dim1], dabs(r__1)); +/* L20: */ + } +/* L30: */ + } + +/* + Index IP is used to specify the real or complex eigenvalue: + IP = 0, real eigenvalue, + 1, first of conjugate complex pair: (wr,wi) + -1, second of conjugate complex pair: (wr,wi) +*/ + + n2 = *n << 1; + + if (rightv) { + +/* Compute right eigenvectors. */ + + ip = 0; + is = *m; + for (ki = *n; ki >= 1; --ki) { + + if (ip == 1) { + goto L130; + } + if (ki == 1) { + goto L40; + } + if (t[ki + (ki - 1) * t_dim1] == 0.f) { + goto L40; + } + ip = -1; + +L40: + if (somev) { + if (ip == 0) { + if (! select[ki]) { + goto L130; + } + } else { + if (! select[ki - 1]) { + goto L130; + } + } + } + +/* Compute the KI-th eigenvalue (WR,WI). */ + + wr = t[ki + ki * t_dim1]; + wi = 0.f; + if (ip != 0) { + wi = sqrt((r__1 = t[ki + (ki - 1) * t_dim1], dabs(r__1))) * + sqrt((r__2 = t[ki - 1 + ki * t_dim1], dabs(r__2))); + } +/* Computing MAX */ + r__1 = ulp * (dabs(wr) + dabs(wi)); + smin = dmax(r__1,smlnum); + + if (ip == 0) { + +/* Real right eigenvector */ + + work[ki + *n] = 1.f; + +/* Form right-hand side */ + + i__1 = ki - 1; + for (k = 1; k <= i__1; ++k) { + work[k + *n] = -t[k + ki * t_dim1]; +/* L50: */ + } + +/* + Solve the upper quasi-triangular system: + (T(1:KI-1,1:KI-1) - WR)*X = SCALE*WORK. +*/ + + jnxt = ki - 1; + for (j = ki - 1; j >= 1; --j) { + if (j > jnxt) { + goto L60; + } + j1 = j; + j2 = j; + jnxt = j - 1; + if (j > 1) { + if (t[j + (j - 1) * t_dim1] != 0.f) { + j1 = j - 1; + jnxt = j - 2; + } + } + + if (j1 == j2) { + +/* 1-by-1 diagonal block */ + + slaln2_(&c_false, &c__1, &c__1, &smin, &c_b15, &t[j + + j * t_dim1], ldt, &c_b15, &c_b15, &work[j + * + n], n, &wr, &c_b29, x, &c__2, &scale, &xnorm, + &ierr); + +/* + Scale X(1,1) to avoid overflow when updating + the right-hand side. +*/ + + if (xnorm > 1.f) { + if (work[j] > bignum / xnorm) { + x[0] /= xnorm; + scale /= xnorm; + } + } + +/* Scale if necessary */ + + if (scale != 1.f) { + sscal_(&ki, &scale, &work[*n + 1], &c__1); + } + work[j + *n] = x[0]; + +/* Update right-hand side */ + + i__1 = j - 1; + r__1 = -x[0]; + saxpy_(&i__1, &r__1, &t[j * t_dim1 + 1], &c__1, &work[ + *n + 1], &c__1); + + } else { + +/* 2-by-2 diagonal block */ + + slaln2_(&c_false, &c__2, &c__1, &smin, &c_b15, &t[j - + 1 + (j - 1) * t_dim1], ldt, &c_b15, &c_b15, & + work[j - 1 + *n], n, &wr, &c_b29, x, &c__2, & + scale, &xnorm, &ierr); + +/* + Scale X(1,1) and X(2,1) to avoid overflow when + updating the right-hand side. +*/ + + if (xnorm > 1.f) { +/* Computing MAX */ + r__1 = work[j - 1], r__2 = work[j]; + beta = dmax(r__1,r__2); + if (beta > bignum / xnorm) { + x[0] /= xnorm; + x[1] /= xnorm; + scale /= xnorm; + } + } + +/* Scale if necessary */ + + if (scale != 1.f) { + sscal_(&ki, &scale, &work[*n + 1], &c__1); + } + work[j - 1 + *n] = x[0]; + work[j + *n] = x[1]; + +/* Update right-hand side */ + + i__1 = j - 2; + r__1 = -x[0]; + saxpy_(&i__1, &r__1, &t[(j - 1) * t_dim1 + 1], &c__1, + &work[*n + 1], &c__1); + i__1 = j - 2; + r__1 = -x[1]; + saxpy_(&i__1, &r__1, &t[j * t_dim1 + 1], &c__1, &work[ + *n + 1], &c__1); + } +L60: + ; + } + +/* Copy the vector x or Q*x to VR and normalize. */ + + if (! over) { + scopy_(&ki, &work[*n + 1], &c__1, &vr[is * vr_dim1 + 1], & + c__1); + + ii = isamax_(&ki, &vr[is * vr_dim1 + 1], &c__1); + remax = 1.f / (r__1 = vr[ii + is * vr_dim1], dabs(r__1)); + sscal_(&ki, &remax, &vr[is * vr_dim1 + 1], &c__1); + + i__1 = *n; + for (k = ki + 1; k <= i__1; ++k) { + vr[k + is * vr_dim1] = 0.f; +/* L70: */ + } + } else { + if (ki > 1) { + i__1 = ki - 1; + sgemv_("N", n, &i__1, &c_b15, &vr[vr_offset], ldvr, & + work[*n + 1], &c__1, &work[ki + *n], &vr[ki * + vr_dim1 + 1], &c__1); + } + + ii = isamax_(n, &vr[ki * vr_dim1 + 1], &c__1); + remax = 1.f / (r__1 = vr[ii + ki * vr_dim1], dabs(r__1)); + sscal_(n, &remax, &vr[ki * vr_dim1 + 1], &c__1); + } + + } else { + +/* + Complex right eigenvector. + + Initial solve + [ (T(KI-1,KI-1) T(KI-1,KI) ) - (WR + I* WI)]*X = 0. + [ (T(KI,KI-1) T(KI,KI) ) ] +*/ + + if ((r__1 = t[ki - 1 + ki * t_dim1], dabs(r__1)) >= (r__2 = t[ + ki + (ki - 1) * t_dim1], dabs(r__2))) { + work[ki - 1 + *n] = 1.f; + work[ki + n2] = wi / t[ki - 1 + ki * t_dim1]; + } else { + work[ki - 1 + *n] = -wi / t[ki + (ki - 1) * t_dim1]; + work[ki + n2] = 1.f; + } + work[ki + *n] = 0.f; + work[ki - 1 + n2] = 0.f; + +/* Form right-hand side */ + + i__1 = ki - 2; + for (k = 1; k <= i__1; ++k) { + work[k + *n] = -work[ki - 1 + *n] * t[k + (ki - 1) * + t_dim1]; + work[k + n2] = -work[ki + n2] * t[k + ki * t_dim1]; +/* L80: */ + } + +/* + Solve upper quasi-triangular system: + (T(1:KI-2,1:KI-2) - (WR+i*WI))*X = SCALE*(WORK+i*WORK2) +*/ + + jnxt = ki - 2; + for (j = ki - 2; j >= 1; --j) { + if (j > jnxt) { + goto L90; + } + j1 = j; + j2 = j; + jnxt = j - 1; + if (j > 1) { + if (t[j + (j - 1) * t_dim1] != 0.f) { + j1 = j - 1; + jnxt = j - 2; + } + } + + if (j1 == j2) { + +/* 1-by-1 diagonal block */ + + slaln2_(&c_false, &c__1, &c__2, &smin, &c_b15, &t[j + + j * t_dim1], ldt, &c_b15, &c_b15, &work[j + * + n], n, &wr, &wi, x, &c__2, &scale, &xnorm, & + ierr); + +/* + Scale X(1,1) and X(1,2) to avoid overflow when + updating the right-hand side. +*/ + + if (xnorm > 1.f) { + if (work[j] > bignum / xnorm) { + x[0] /= xnorm; + x[2] /= xnorm; + scale /= xnorm; + } + } + +/* Scale if necessary */ + + if (scale != 1.f) { + sscal_(&ki, &scale, &work[*n + 1], &c__1); + sscal_(&ki, &scale, &work[n2 + 1], &c__1); + } + work[j + *n] = x[0]; + work[j + n2] = x[2]; + +/* Update the right-hand side */ + + i__1 = j - 1; + r__1 = -x[0]; + saxpy_(&i__1, &r__1, &t[j * t_dim1 + 1], &c__1, &work[ + *n + 1], &c__1); + i__1 = j - 1; + r__1 = -x[2]; + saxpy_(&i__1, &r__1, &t[j * t_dim1 + 1], &c__1, &work[ + n2 + 1], &c__1); + + } else { + +/* 2-by-2 diagonal block */ + + slaln2_(&c_false, &c__2, &c__2, &smin, &c_b15, &t[j - + 1 + (j - 1) * t_dim1], ldt, &c_b15, &c_b15, & + work[j - 1 + *n], n, &wr, &wi, x, &c__2, & + scale, &xnorm, &ierr); + +/* + Scale X to avoid overflow when updating + the right-hand side. +*/ + + if (xnorm > 1.f) { +/* Computing MAX */ + r__1 = work[j - 1], r__2 = work[j]; + beta = dmax(r__1,r__2); + if (beta > bignum / xnorm) { + rec = 1.f / xnorm; + x[0] *= rec; + x[2] *= rec; + x[1] *= rec; + x[3] *= rec; + scale *= rec; + } + } + +/* Scale if necessary */ + + if (scale != 1.f) { + sscal_(&ki, &scale, &work[*n + 1], &c__1); + sscal_(&ki, &scale, &work[n2 + 1], &c__1); + } + work[j - 1 + *n] = x[0]; + work[j + *n] = x[1]; + work[j - 1 + n2] = x[2]; + work[j + n2] = x[3]; + +/* Update the right-hand side */ + + i__1 = j - 2; + r__1 = -x[0]; + saxpy_(&i__1, &r__1, &t[(j - 1) * t_dim1 + 1], &c__1, + &work[*n + 1], &c__1); + i__1 = j - 2; + r__1 = -x[1]; + saxpy_(&i__1, &r__1, &t[j * t_dim1 + 1], &c__1, &work[ + *n + 1], &c__1); + i__1 = j - 2; + r__1 = -x[2]; + saxpy_(&i__1, &r__1, &t[(j - 1) * t_dim1 + 1], &c__1, + &work[n2 + 1], &c__1); + i__1 = j - 2; + r__1 = -x[3]; + saxpy_(&i__1, &r__1, &t[j * t_dim1 + 1], &c__1, &work[ + n2 + 1], &c__1); + } +L90: + ; + } + +/* Copy the vector x or Q*x to VR and normalize. */ + + if (! over) { + scopy_(&ki, &work[*n + 1], &c__1, &vr[(is - 1) * vr_dim1 + + 1], &c__1); + scopy_(&ki, &work[n2 + 1], &c__1, &vr[is * vr_dim1 + 1], & + c__1); + + emax = 0.f; + i__1 = ki; + for (k = 1; k <= i__1; ++k) { +/* Computing MAX */ + r__3 = emax, r__4 = (r__1 = vr[k + (is - 1) * vr_dim1] + , dabs(r__1)) + (r__2 = vr[k + is * vr_dim1], + dabs(r__2)); + emax = dmax(r__3,r__4); +/* L100: */ + } + + remax = 1.f / emax; + sscal_(&ki, &remax, &vr[(is - 1) * vr_dim1 + 1], &c__1); + sscal_(&ki, &remax, &vr[is * vr_dim1 + 1], &c__1); + + i__1 = *n; + for (k = ki + 1; k <= i__1; ++k) { + vr[k + (is - 1) * vr_dim1] = 0.f; + vr[k + is * vr_dim1] = 0.f; +/* L110: */ + } + + } else { + + if (ki > 2) { + i__1 = ki - 2; + sgemv_("N", n, &i__1, &c_b15, &vr[vr_offset], ldvr, & + work[*n + 1], &c__1, &work[ki - 1 + *n], &vr[( + ki - 1) * vr_dim1 + 1], &c__1); + i__1 = ki - 2; + sgemv_("N", n, &i__1, &c_b15, &vr[vr_offset], ldvr, & + work[n2 + 1], &c__1, &work[ki + n2], &vr[ki * + vr_dim1 + 1], &c__1); + } else { + sscal_(n, &work[ki - 1 + *n], &vr[(ki - 1) * vr_dim1 + + 1], &c__1); + sscal_(n, &work[ki + n2], &vr[ki * vr_dim1 + 1], & + c__1); + } + + emax = 0.f; + i__1 = *n; + for (k = 1; k <= i__1; ++k) { +/* Computing MAX */ + r__3 = emax, r__4 = (r__1 = vr[k + (ki - 1) * vr_dim1] + , dabs(r__1)) + (r__2 = vr[k + ki * vr_dim1], + dabs(r__2)); + emax = dmax(r__3,r__4); +/* L120: */ + } + remax = 1.f / emax; + sscal_(n, &remax, &vr[(ki - 1) * vr_dim1 + 1], &c__1); + sscal_(n, &remax, &vr[ki * vr_dim1 + 1], &c__1); + } + } + + --is; + if (ip != 0) { + --is; + } +L130: + if (ip == 1) { + ip = 0; + } + if (ip == -1) { + ip = 1; + } +/* L140: */ + } + } + + if (leftv) { + +/* Compute left eigenvectors. */ + + ip = 0; + is = 1; + i__1 = *n; + for (ki = 1; ki <= i__1; ++ki) { + + if (ip == -1) { + goto L250; + } + if (ki == *n) { + goto L150; + } + if (t[ki + 1 + ki * t_dim1] == 0.f) { + goto L150; + } + ip = 1; + +L150: + if (somev) { + if (! select[ki]) { + goto L250; + } + } + +/* Compute the KI-th eigenvalue (WR,WI). */ + + wr = t[ki + ki * t_dim1]; + wi = 0.f; + if (ip != 0) { + wi = sqrt((r__1 = t[ki + (ki + 1) * t_dim1], dabs(r__1))) * + sqrt((r__2 = t[ki + 1 + ki * t_dim1], dabs(r__2))); + } +/* Computing MAX */ + r__1 = ulp * (dabs(wr) + dabs(wi)); + smin = dmax(r__1,smlnum); + + if (ip == 0) { + +/* Real left eigenvector. */ + + work[ki + *n] = 1.f; + +/* Form right-hand side */ + + i__2 = *n; + for (k = ki + 1; k <= i__2; ++k) { + work[k + *n] = -t[ki + k * t_dim1]; +/* L160: */ + } + +/* + Solve the quasi-triangular system: + (T(KI+1:N,KI+1:N) - WR)'*X = SCALE*WORK +*/ + + vmax = 1.f; + vcrit = bignum; + + jnxt = ki + 1; + i__2 = *n; + for (j = ki + 1; j <= i__2; ++j) { + if (j < jnxt) { + goto L170; + } + j1 = j; + j2 = j; + jnxt = j + 1; + if (j < *n) { + if (t[j + 1 + j * t_dim1] != 0.f) { + j2 = j + 1; + jnxt = j + 2; + } + } + + if (j1 == j2) { + +/* + 1-by-1 diagonal block + + Scale if necessary to avoid overflow when forming + the right-hand side. +*/ + + if (work[j] > vcrit) { + rec = 1.f / vmax; + i__3 = *n - ki + 1; + sscal_(&i__3, &rec, &work[ki + *n], &c__1); + vmax = 1.f; + vcrit = bignum; + } + + i__3 = j - ki - 1; + work[j + *n] -= sdot_(&i__3, &t[ki + 1 + j * t_dim1], + &c__1, &work[ki + 1 + *n], &c__1); + +/* Solve (T(J,J)-WR)'*X = WORK */ + + slaln2_(&c_false, &c__1, &c__1, &smin, &c_b15, &t[j + + j * t_dim1], ldt, &c_b15, &c_b15, &work[j + * + n], n, &wr, &c_b29, x, &c__2, &scale, &xnorm, + &ierr); + +/* Scale if necessary */ + + if (scale != 1.f) { + i__3 = *n - ki + 1; + sscal_(&i__3, &scale, &work[ki + *n], &c__1); + } + work[j + *n] = x[0]; +/* Computing MAX */ + r__2 = (r__1 = work[j + *n], dabs(r__1)); + vmax = dmax(r__2,vmax); + vcrit = bignum / vmax; + + } else { + +/* + 2-by-2 diagonal block + + Scale if necessary to avoid overflow when forming + the right-hand side. + + Computing MAX +*/ + r__1 = work[j], r__2 = work[j + 1]; + beta = dmax(r__1,r__2); + if (beta > vcrit) { + rec = 1.f / vmax; + i__3 = *n - ki + 1; + sscal_(&i__3, &rec, &work[ki + *n], &c__1); + vmax = 1.f; + vcrit = bignum; + } + + i__3 = j - ki - 1; + work[j + *n] -= sdot_(&i__3, &t[ki + 1 + j * t_dim1], + &c__1, &work[ki + 1 + *n], &c__1); + + i__3 = j - ki - 1; + work[j + 1 + *n] -= sdot_(&i__3, &t[ki + 1 + (j + 1) * + t_dim1], &c__1, &work[ki + 1 + *n], &c__1); + +/* + Solve + [T(J,J)-WR T(J,J+1) ]'* X = SCALE*( WORK1 ) + [T(J+1,J) T(J+1,J+1)-WR] ( WORK2 ) +*/ + + slaln2_(&c_true, &c__2, &c__1, &smin, &c_b15, &t[j + + j * t_dim1], ldt, &c_b15, &c_b15, &work[j + * + n], n, &wr, &c_b29, x, &c__2, &scale, &xnorm, + &ierr); + +/* Scale if necessary */ + + if (scale != 1.f) { + i__3 = *n - ki + 1; + sscal_(&i__3, &scale, &work[ki + *n], &c__1); + } + work[j + *n] = x[0]; + work[j + 1 + *n] = x[1]; + +/* Computing MAX */ + r__3 = (r__1 = work[j + *n], dabs(r__1)), r__4 = ( + r__2 = work[j + 1 + *n], dabs(r__2)), r__3 = + max(r__3,r__4); + vmax = dmax(r__3,vmax); + vcrit = bignum / vmax; + + } +L170: + ; + } + +/* Copy the vector x or Q*x to VL and normalize. */ + + if (! over) { + i__2 = *n - ki + 1; + scopy_(&i__2, &work[ki + *n], &c__1, &vl[ki + is * + vl_dim1], &c__1); + + i__2 = *n - ki + 1; + ii = isamax_(&i__2, &vl[ki + is * vl_dim1], &c__1) + ki - + 1; + remax = 1.f / (r__1 = vl[ii + is * vl_dim1], dabs(r__1)); + i__2 = *n - ki + 1; + sscal_(&i__2, &remax, &vl[ki + is * vl_dim1], &c__1); + + i__2 = ki - 1; + for (k = 1; k <= i__2; ++k) { + vl[k + is * vl_dim1] = 0.f; +/* L180: */ + } + + } else { + + if (ki < *n) { + i__2 = *n - ki; + sgemv_("N", n, &i__2, &c_b15, &vl[(ki + 1) * vl_dim1 + + 1], ldvl, &work[ki + 1 + *n], &c__1, &work[ + ki + *n], &vl[ki * vl_dim1 + 1], &c__1); + } + + ii = isamax_(n, &vl[ki * vl_dim1 + 1], &c__1); + remax = 1.f / (r__1 = vl[ii + ki * vl_dim1], dabs(r__1)); + sscal_(n, &remax, &vl[ki * vl_dim1 + 1], &c__1); + + } + + } else { + +/* + Complex left eigenvector. + + Initial solve: + ((T(KI,KI) T(KI,KI+1) )' - (WR - I* WI))*X = 0. + ((T(KI+1,KI) T(KI+1,KI+1)) ) +*/ + + if ((r__1 = t[ki + (ki + 1) * t_dim1], dabs(r__1)) >= (r__2 = + t[ki + 1 + ki * t_dim1], dabs(r__2))) { + work[ki + *n] = wi / t[ki + (ki + 1) * t_dim1]; + work[ki + 1 + n2] = 1.f; + } else { + work[ki + *n] = 1.f; + work[ki + 1 + n2] = -wi / t[ki + 1 + ki * t_dim1]; + } + work[ki + 1 + *n] = 0.f; + work[ki + n2] = 0.f; + +/* Form right-hand side */ + + i__2 = *n; + for (k = ki + 2; k <= i__2; ++k) { + work[k + *n] = -work[ki + *n] * t[ki + k * t_dim1]; + work[k + n2] = -work[ki + 1 + n2] * t[ki + 1 + k * t_dim1] + ; +/* L190: */ + } + +/* + Solve complex quasi-triangular system: + ( T(KI+2,N:KI+2,N) - (WR-i*WI) )*X = WORK1+i*WORK2 +*/ + + vmax = 1.f; + vcrit = bignum; + + jnxt = ki + 2; + i__2 = *n; + for (j = ki + 2; j <= i__2; ++j) { + if (j < jnxt) { + goto L200; + } + j1 = j; + j2 = j; + jnxt = j + 1; + if (j < *n) { + if (t[j + 1 + j * t_dim1] != 0.f) { + j2 = j + 1; + jnxt = j + 2; + } + } + + if (j1 == j2) { + +/* + 1-by-1 diagonal block + + Scale if necessary to avoid overflow when + forming the right-hand side elements. +*/ + + if (work[j] > vcrit) { + rec = 1.f / vmax; + i__3 = *n - ki + 1; + sscal_(&i__3, &rec, &work[ki + *n], &c__1); + i__3 = *n - ki + 1; + sscal_(&i__3, &rec, &work[ki + n2], &c__1); + vmax = 1.f; + vcrit = bignum; + } + + i__3 = j - ki - 2; + work[j + *n] -= sdot_(&i__3, &t[ki + 2 + j * t_dim1], + &c__1, &work[ki + 2 + *n], &c__1); + i__3 = j - ki - 2; + work[j + n2] -= sdot_(&i__3, &t[ki + 2 + j * t_dim1], + &c__1, &work[ki + 2 + n2], &c__1); + +/* Solve (T(J,J)-(WR-i*WI))*(X11+i*X12)= WK+I*WK2 */ + + r__1 = -wi; + slaln2_(&c_false, &c__1, &c__2, &smin, &c_b15, &t[j + + j * t_dim1], ldt, &c_b15, &c_b15, &work[j + * + n], n, &wr, &r__1, x, &c__2, &scale, &xnorm, & + ierr); + +/* Scale if necessary */ + + if (scale != 1.f) { + i__3 = *n - ki + 1; + sscal_(&i__3, &scale, &work[ki + *n], &c__1); + i__3 = *n - ki + 1; + sscal_(&i__3, &scale, &work[ki + n2], &c__1); + } + work[j + *n] = x[0]; + work[j + n2] = x[2]; +/* Computing MAX */ + r__3 = (r__1 = work[j + *n], dabs(r__1)), r__4 = ( + r__2 = work[j + n2], dabs(r__2)), r__3 = max( + r__3,r__4); + vmax = dmax(r__3,vmax); + vcrit = bignum / vmax; + + } else { + +/* + 2-by-2 diagonal block + + Scale if necessary to avoid overflow when forming + the right-hand side elements. + + Computing MAX +*/ + r__1 = work[j], r__2 = work[j + 1]; + beta = dmax(r__1,r__2); + if (beta > vcrit) { + rec = 1.f / vmax; + i__3 = *n - ki + 1; + sscal_(&i__3, &rec, &work[ki + *n], &c__1); + i__3 = *n - ki + 1; + sscal_(&i__3, &rec, &work[ki + n2], &c__1); + vmax = 1.f; + vcrit = bignum; + } + + i__3 = j - ki - 2; + work[j + *n] -= sdot_(&i__3, &t[ki + 2 + j * t_dim1], + &c__1, &work[ki + 2 + *n], &c__1); + + i__3 = j - ki - 2; + work[j + n2] -= sdot_(&i__3, &t[ki + 2 + j * t_dim1], + &c__1, &work[ki + 2 + n2], &c__1); + + i__3 = j - ki - 2; + work[j + 1 + *n] -= sdot_(&i__3, &t[ki + 2 + (j + 1) * + t_dim1], &c__1, &work[ki + 2 + *n], &c__1); + + i__3 = j - ki - 2; + work[j + 1 + n2] -= sdot_(&i__3, &t[ki + 2 + (j + 1) * + t_dim1], &c__1, &work[ki + 2 + n2], &c__1); + +/* + Solve 2-by-2 complex linear equation + ([T(j,j) T(j,j+1) ]'-(wr-i*wi)*I)*X = SCALE*B + ([T(j+1,j) T(j+1,j+1)] ) +*/ + + r__1 = -wi; + slaln2_(&c_true, &c__2, &c__2, &smin, &c_b15, &t[j + + j * t_dim1], ldt, &c_b15, &c_b15, &work[j + * + n], n, &wr, &r__1, x, &c__2, &scale, &xnorm, & + ierr); + +/* Scale if necessary */ + + if (scale != 1.f) { + i__3 = *n - ki + 1; + sscal_(&i__3, &scale, &work[ki + *n], &c__1); + i__3 = *n - ki + 1; + sscal_(&i__3, &scale, &work[ki + n2], &c__1); + } + work[j + *n] = x[0]; + work[j + n2] = x[2]; + work[j + 1 + *n] = x[1]; + work[j + 1 + n2] = x[3]; +/* Computing MAX */ + r__1 = dabs(x[0]), r__2 = dabs(x[2]), r__1 = max(r__1, + r__2), r__2 = dabs(x[1]), r__1 = max(r__1, + r__2), r__2 = dabs(x[3]), r__1 = max(r__1, + r__2); + vmax = dmax(r__1,vmax); + vcrit = bignum / vmax; + + } +L200: + ; + } + +/* + Copy the vector x or Q*x to VL and normalize. + + L210: +*/ + if (! over) { + i__2 = *n - ki + 1; + scopy_(&i__2, &work[ki + *n], &c__1, &vl[ki + is * + vl_dim1], &c__1); + i__2 = *n - ki + 1; + scopy_(&i__2, &work[ki + n2], &c__1, &vl[ki + (is + 1) * + vl_dim1], &c__1); + + emax = 0.f; + i__2 = *n; + for (k = ki; k <= i__2; ++k) { +/* Computing MAX */ + r__3 = emax, r__4 = (r__1 = vl[k + is * vl_dim1], + dabs(r__1)) + (r__2 = vl[k + (is + 1) * + vl_dim1], dabs(r__2)); + emax = dmax(r__3,r__4); +/* L220: */ + } + remax = 1.f / emax; + i__2 = *n - ki + 1; + sscal_(&i__2, &remax, &vl[ki + is * vl_dim1], &c__1); + i__2 = *n - ki + 1; + sscal_(&i__2, &remax, &vl[ki + (is + 1) * vl_dim1], &c__1) + ; + + i__2 = ki - 1; + for (k = 1; k <= i__2; ++k) { + vl[k + is * vl_dim1] = 0.f; + vl[k + (is + 1) * vl_dim1] = 0.f; +/* L230: */ + } + } else { + if (ki < *n - 1) { + i__2 = *n - ki - 1; + sgemv_("N", n, &i__2, &c_b15, &vl[(ki + 2) * vl_dim1 + + 1], ldvl, &work[ki + 2 + *n], &c__1, &work[ + ki + *n], &vl[ki * vl_dim1 + 1], &c__1); + i__2 = *n - ki - 1; + sgemv_("N", n, &i__2, &c_b15, &vl[(ki + 2) * vl_dim1 + + 1], ldvl, &work[ki + 2 + n2], &c__1, &work[ + ki + 1 + n2], &vl[(ki + 1) * vl_dim1 + 1], & + c__1); + } else { + sscal_(n, &work[ki + *n], &vl[ki * vl_dim1 + 1], & + c__1); + sscal_(n, &work[ki + 1 + n2], &vl[(ki + 1) * vl_dim1 + + 1], &c__1); + } + + emax = 0.f; + i__2 = *n; + for (k = 1; k <= i__2; ++k) { +/* Computing MAX */ + r__3 = emax, r__4 = (r__1 = vl[k + ki * vl_dim1], + dabs(r__1)) + (r__2 = vl[k + (ki + 1) * + vl_dim1], dabs(r__2)); + emax = dmax(r__3,r__4); +/* L240: */ + } + remax = 1.f / emax; + sscal_(n, &remax, &vl[ki * vl_dim1 + 1], &c__1); + sscal_(n, &remax, &vl[(ki + 1) * vl_dim1 + 1], &c__1); + + } + + } + + ++is; + if (ip != 0) { + ++is; + } +L250: + if (ip == -1) { + ip = 0; + } + if (ip == 1) { + ip = -1; + } + +/* L260: */ + } + + } + + return 0; + +/* End of STREVC */ + +} /* strevc_ */ + +/* Subroutine */ int strti2_(char *uplo, char *diag, integer *n, real *a, + integer *lda, integer *info) +{ + /* System generated locals */ + integer a_dim1, a_offset, i__1, i__2; + + /* Local variables */ + static integer j; + static real ajj; + extern logical lsame_(char *, char *); + extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *); + static logical upper; + extern /* Subroutine */ int strmv_(char *, char *, char *, integer *, + real *, integer *, real *, integer *), + xerbla_(char *, integer *); + static logical nounit; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + February 29, 1992 + + + Purpose + ======= + + STRTI2 computes the inverse of a real upper or lower triangular + matrix. + + This is the Level 2 BLAS version of the algorithm. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + Specifies whether the matrix A is upper or lower triangular. + = 'U': Upper triangular + = 'L': Lower triangular + + DIAG (input) CHARACTER*1 + Specifies whether or not the matrix A is unit triangular. + = 'N': Non-unit triangular + = 'U': Unit triangular + + N (input) INTEGER + The order of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the triangular matrix A. If UPLO = 'U', the + leading n by n upper triangular part of the array A contains + the upper triangular matrix, and the strictly lower + triangular part of A is not referenced. If UPLO = 'L', the + leading n by n lower triangular part of the array A contains + the lower triangular matrix, and the strictly upper + triangular part of A is not referenced. If DIAG = 'U', the + diagonal elements of A are also not referenced and are + assumed to be 1. + + On exit, the (triangular) inverse of the original matrix, in + the same storage format. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -k, the k-th argument had an illegal value + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + + /* Function Body */ + *info = 0; + upper = lsame_(uplo, "U"); + nounit = lsame_(diag, "N"); + if (! upper && ! lsame_(uplo, "L")) { + *info = -1; + } else if (! nounit && ! lsame_(diag, "U")) { + *info = -2; + } else if (*n < 0) { + *info = -3; + } else if (*lda < max(1,*n)) { + *info = -5; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("STRTI2", &i__1); + return 0; + } + + if (upper) { + +/* Compute inverse of upper triangular matrix. */ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + if (nounit) { + a[j + j * a_dim1] = 1.f / a[j + j * a_dim1]; + ajj = -a[j + j * a_dim1]; + } else { + ajj = -1.f; + } + +/* Compute elements 1:j-1 of j-th column. */ + + i__2 = j - 1; + strmv_("Upper", "No transpose", diag, &i__2, &a[a_offset], lda, & + a[j * a_dim1 + 1], &c__1); + i__2 = j - 1; + sscal_(&i__2, &ajj, &a[j * a_dim1 + 1], &c__1); +/* L10: */ + } + } else { + +/* Compute inverse of lower triangular matrix. */ + + for (j = *n; j >= 1; --j) { + if (nounit) { + a[j + j * a_dim1] = 1.f / a[j + j * a_dim1]; + ajj = -a[j + j * a_dim1]; + } else { + ajj = -1.f; + } + if (j < *n) { + +/* Compute elements j+1:n of j-th column. */ + + i__1 = *n - j; + strmv_("Lower", "No transpose", diag, &i__1, &a[j + 1 + (j + + 1) * a_dim1], lda, &a[j + 1 + j * a_dim1], &c__1); + i__1 = *n - j; + sscal_(&i__1, &ajj, &a[j + 1 + j * a_dim1], &c__1); + } +/* L20: */ + } + } + + return 0; + +/* End of STRTI2 */ + +} /* strti2_ */ + +/* Subroutine */ int strtri_(char *uplo, char *diag, integer *n, real *a, + integer *lda, integer *info) +{ + /* System generated locals */ + address a__1[2]; + integer a_dim1, a_offset, i__1, i__2[2], i__3, i__4, i__5; + char ch__1[2]; + + /* Builtin functions */ + /* Subroutine */ int s_cat(char *, char **, integer *, integer *, ftnlen); + + /* Local variables */ + static integer j, jb, nb, nn; + extern logical lsame_(char *, char *); + static logical upper; + extern /* Subroutine */ int strmm_(char *, char *, char *, char *, + integer *, integer *, real *, real *, integer *, real *, integer * + ), strsm_(char *, char *, char *, + char *, integer *, integer *, real *, real *, integer *, real *, + integer *), strti2_(char *, char * + , integer *, real *, integer *, integer *), + xerbla_(char *, integer *); + extern integer ilaenv_(integer *, char *, char *, integer *, integer *, + integer *, integer *, ftnlen, ftnlen); + static logical nounit; + + +/* + -- LAPACK routine (version 3.0) -- + Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., + Courant Institute, Argonne National Lab, and Rice University + March 31, 1993 + + + Purpose + ======= + + STRTRI computes the inverse of a real upper or lower triangular + matrix A. + + This is the Level 3 BLAS version of the algorithm. + + Arguments + ========= + + UPLO (input) CHARACTER*1 + = 'U': A is upper triangular; + = 'L': A is lower triangular. + + DIAG (input) CHARACTER*1 + = 'N': A is non-unit triangular; + = 'U': A is unit triangular. + + N (input) INTEGER + The order of the matrix A. N >= 0. + + A (input/output) REAL array, dimension (LDA,N) + On entry, the triangular matrix A. If UPLO = 'U', the + leading N-by-N upper triangular part of the array A contains + the upper triangular matrix, and the strictly lower + triangular part of A is not referenced. If UPLO = 'L', the + leading N-by-N lower triangular part of the array A contains + the lower triangular matrix, and the strictly upper + triangular part of A is not referenced. If DIAG = 'U', the + diagonal elements of A are also not referenced and are + assumed to be 1. + On exit, the (triangular) inverse of the original matrix, in + the same storage format. + + LDA (input) INTEGER + The leading dimension of the array A. LDA >= max(1,N). + + INFO (output) INTEGER + = 0: successful exit + < 0: if INFO = -i, the i-th argument had an illegal value + > 0: if INFO = i, A(i,i) is exactly zero. The triangular + matrix is singular and its inverse can not be computed. + + ===================================================================== + + + Test the input parameters. +*/ + + /* Parameter adjustments */ + a_dim1 = *lda; + a_offset = 1 + a_dim1; + a -= a_offset; + + /* Function Body */ + *info = 0; + upper = lsame_(uplo, "U"); + nounit = lsame_(diag, "N"); + if (! upper && ! lsame_(uplo, "L")) { + *info = -1; + } else if (! nounit && ! lsame_(diag, "U")) { + *info = -2; + } else if (*n < 0) { + *info = -3; + } else if (*lda < max(1,*n)) { + *info = -5; + } + if (*info != 0) { + i__1 = -(*info); + xerbla_("STRTRI", &i__1); + return 0; + } + +/* Quick return if possible */ + + if (*n == 0) { + return 0; + } + +/* Check for singularity if non-unit. */ + + if (nounit) { + i__1 = *n; + for (*info = 1; *info <= i__1; ++(*info)) { + if (a[*info + *info * a_dim1] == 0.f) { + return 0; + } +/* L10: */ + } + *info = 0; + } + +/* + Determine the block size for this environment. + + Writing concatenation +*/ + i__2[0] = 1, a__1[0] = uplo; + i__2[1] = 1, a__1[1] = diag; + s_cat(ch__1, a__1, i__2, &c__2, (ftnlen)2); + nb = ilaenv_(&c__1, "STRTRI", ch__1, n, &c_n1, &c_n1, &c_n1, (ftnlen)6, ( + ftnlen)2); + if (nb <= 1 || nb >= *n) { + +/* Use unblocked code */ + + strti2_(uplo, diag, n, &a[a_offset], lda, info); + } else { + +/* Use blocked code */ + + if (upper) { + +/* Compute inverse of upper triangular matrix */ + + i__1 = *n; + i__3 = nb; + for (j = 1; i__3 < 0 ? j >= i__1 : j <= i__1; j += i__3) { +/* Computing MIN */ + i__4 = nb, i__5 = *n - j + 1; + jb = min(i__4,i__5); + +/* Compute rows 1:j-1 of current block column */ + + i__4 = j - 1; + strmm_("Left", "Upper", "No transpose", diag, &i__4, &jb, & + c_b15, &a[a_offset], lda, &a[j * a_dim1 + 1], lda); + i__4 = j - 1; + strsm_("Right", "Upper", "No transpose", diag, &i__4, &jb, & + c_b151, &a[j + j * a_dim1], lda, &a[j * a_dim1 + 1], + lda); + +/* Compute inverse of current diagonal block */ + + strti2_("Upper", diag, &jb, &a[j + j * a_dim1], lda, info); +/* L20: */ + } + } else { + +/* Compute inverse of lower triangular matrix */ + + nn = (*n - 1) / nb * nb + 1; + i__3 = -nb; + for (j = nn; i__3 < 0 ? j >= 1 : j <= 1; j += i__3) { +/* Computing MIN */ + i__1 = nb, i__4 = *n - j + 1; + jb = min(i__1,i__4); + if (j + jb <= *n) { + +/* Compute rows j+jb:n of current block column */ + + i__1 = *n - j - jb + 1; + strmm_("Left", "Lower", "No transpose", diag, &i__1, &jb, + &c_b15, &a[j + jb + (j + jb) * a_dim1], lda, &a[j + + jb + j * a_dim1], lda); + i__1 = *n - j - jb + 1; + strsm_("Right", "Lower", "No transpose", diag, &i__1, &jb, + &c_b151, &a[j + j * a_dim1], lda, &a[j + jb + j * + a_dim1], lda); + } + +/* Compute inverse of current diagonal block */ + + strti2_("Lower", diag, &jb, &a[j + j * a_dim1], lda, info); +/* L30: */ + } + } + } + + return 0; + +/* End of STRTRI */ + +} /* strtri_ */ + |