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Diffstat (limited to 'libquadmath/math/ctanhq.c')
| -rw-r--r-- | libquadmath/math/ctanhq.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/libquadmath/math/ctanhq.c b/libquadmath/math/ctanhq.c new file mode 100644 index 00000000000..8934cfad59f --- /dev/null +++ b/libquadmath/math/ctanhq.c @@ -0,0 +1,120 @@ +/* Complex hyperbole tangent for __float128. + Copyright (C) 1997-2012 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include "quadmath-imp.h" + +#ifdef HAVE_FENV_H +# include <fenv.h> +#endif + + +__complex128 +ctanhq (__complex128 x) +{ + __complex128 res; + + if (__builtin_expect (!finiteq (__real__ x) || !finiteq (__imag__ x), 0)) + { + if (__quadmath_isinf_nsq (__real__ x)) + { + __real__ res = copysignq (1.0Q, __real__ x); + __imag__ res = copysignq (0.0Q, __imag__ x); + } + else if (__imag__ x == 0.0Q) + { + res = x; + } + else + { + __real__ res = nanq (""); + __imag__ res = nanq (""); + +#ifdef HAVE_FENV_H + if (__quadmath_isinf_nsq (__imag__ x)) + feraiseexcept (FE_INVALID); +#endif + } + } + else + { + __float128 sinix, cosix; + __float128 den; + const int t = (int) ((FLT128_MAX_EXP - 1) * M_LN2q / 2); + int icls = fpclassifyq (__imag__ x); + + /* tanh(x+iy) = (sinh(2x) + i*sin(2y))/(cosh(2x) + cos(2y)) + = (sinh(x)*cosh(x) + i*sin(y)*cos(y))/(sinh(x)^2 + cos(y)^2). */ + + if (__builtin_expect (icls != QUADFP_SUBNORMAL, 1)) + { + sincosq (__imag__ x, &sinix, &cosix); + } + else + { + sinix = __imag__ x; + cosix = 1.0Q; + } + + if (fabsq (__real__ x) > t) + { + /* Avoid intermediate overflow when the imaginary part of + the result may be subnormal. Ignoring negligible terms, + the real part is +/- 1, the imaginary part is + sin(y)*cos(y)/sinh(x)^2 = 4*sin(y)*cos(y)/exp(2x). */ + __float128 exp_2t = expq (2 * t); + + __real__ res = copysignq (1.0, __real__ x); + __imag__ res = 4 * sinix * cosix; + __real__ x = fabsq (__real__ x); + __real__ x -= t; + __imag__ res /= exp_2t; + if (__real__ x > t) + { + /* Underflow (original real part of x has absolute value + > 2t). */ + __imag__ res /= exp_2t; + } + else + __imag__ res /= expq (2 * __real__ x); + } + else + { + __float128 sinhrx, coshrx; + if (fabsq (__real__ x) > FLT128_MIN) + { + sinhrx = sinhq (__real__ x); + coshrx = coshq (__real__ x); + } + else + { + sinhrx = __real__ x; + coshrx = 1.0Q; + } + + if (fabsq (sinhrx) > fabsq (cosix) * FLT128_EPSILON) + den = sinhrx * sinhrx + cosix * cosix; + else + den = cosix * cosix; + __real__ res = sinhrx * coshrx / den; + __imag__ res = sinix * cosix / den; + } + } + + return res; +} |