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| author | Andreas Enge <andreas.enge@inria.fr> | 2012-06-30 14:57:21 +0000 |
|---|---|---|
| committer | Andreas Enge <andreas.enge@inria.fr> | 2012-06-30 14:57:21 +0000 |
| commit | 071fbdde8d9e911422070f1d1fcf20be64531765 (patch) | |
| tree | 3a460cc282f2a63f599f347971f6f71a6939d695 | |
| parent | 9b3c5321ceb6f6bc404abccc86bf1e2385c61907 (diff) | |
| download | mpc-git-071fbdde8d9e911422070f1d1fcf20be64531765.tar.gz | |
log.c: corrected logical error in detection of cancellation
git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/mpc/trunk@1215 211d60ee-9f03-0410-a15a-8952a2c7a4e4
| -rw-r--r-- | src/log.c | 23 |
1 files changed, 4 insertions, 19 deletions
@@ -32,6 +32,7 @@ mpc_log (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd){ int inex_re, inex_im; int err; mpfr_exp_t expw; + int sgnw; /* special values: NaN and infinities */ if (!mpc_fin_p (op)) { @@ -114,23 +115,6 @@ mpc_log (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd){ return MPC_INEX(inex_re, inex_im); } -#define MPC_OUT(x) \ -do { \ - printf (#x "[%lu,%lu]=", (unsigned long int) MPC_PREC_RE (x), \ - (unsigned long int) MPC_PREC_IM (x)); \ - mpc_out_str (stdout, 2, 0, x, MPC_RNDNN); \ - printf ("\n"); \ -} while (0) - -#define MPFR_OUT(x) \ -do { \ - printf (#x "[%lu]=", (unsigned long int) mpfr_get_prec (x)); \ - mpfr_out_str (stdout, 2, 0, x, GMP_RNDN); \ - printf ("\t"); \ - mpfr_out_str (stdout, 10, 0, x, GMP_RNDN); \ - printf ("\n"); \ -} while (0) - prec = MPC_PREC_RE(rop); mpfr_init2 (w, 2); /* let op = x + iy; log = 1/2 log (x^2 + y^2) + i atan2 (y, x) */ @@ -188,10 +172,11 @@ do { \ mpfr_abs (w, x, GMP_RNDN); /* exact */ mpfr_log (w, w, GMP_RNDN); /* error 0.5 ulp */ expw = mpfr_get_exp (w); + sgnw = mpfr_signbit (w); mpfr_add (w, w, v, GMP_RNDN); - if (!mpfr_signbit (w)) /* v is positive, so no cancellation; - error 22.25 ulp; error counts lost bits */ + if (!sgnw) /* v is positive, so no cancellation; + error 22.25 ulp; error counts lost bits */ err = 5; else err = MPC_MAX (5 + mpfr_get_exp (v), |