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Diffstat (limited to 'libquadmath/math/ctanq.c')
| -rw-r--r-- | libquadmath/math/ctanq.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/libquadmath/math/ctanq.c b/libquadmath/math/ctanq.c new file mode 100644 index 0000000..d390511 --- /dev/null +++ b/libquadmath/math/ctanq.c @@ -0,0 +1,120 @@ +/* Complex tangent function for complex __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 +ctanq (__complex128 x) +{ + __complex128 res; + + if (__builtin_expect (!finiteq (__real__ x) || !finiteq (__imag__ x), 0)) + { + if (__quadmath_isinf_nsq (__imag__ x)) + { + __real__ res = copysignq (0.0Q, __real__ x); + __imag__ res = copysignq (1.0Q, __imag__ x); + } + else if (__real__ x == 0.0Q) + { + res = x; + } + else + { + __real__ res = nanq (""); + __imag__ res = nanq (""); + +#ifdef HAVE_FENV_H + if (__quadmath_isinf_nsq (__real__ x)) + feraiseexcept (FE_INVALID); +#endif + } + } + else + { + __float128 sinrx, cosrx; + __float128 den; + const int t = (int) ((FLT128_MAX_EXP - 1) * M_LN2q / 2.0Q); + int rcls = fpclassifyq (__real__ x); + + /* tan(x+iy) = (sin(2x) + i*sinh(2y))/(cos(2x) + cosh(2y)) + = (sin(x)*cos(x) + i*sinh(y)*cosh(y)/(cos(x)^2 + sinh(y)^2). */ + + if (__builtin_expect (rcls != QUADFP_SUBNORMAL, 1)) + { + sincosq (__real__ x, &sinrx, &cosrx); + } + else + { + sinrx = __real__ x; + cosrx = 1.0Q; + } + + if (fabsq (__imag__ x) > t) + { + /* Avoid intermediate overflow when the real part of the + result may be subnormal. Ignoring negligible terms, the + imaginary part is +/- 1, the real part is + sin(x)*cos(x)/sinh(y)^2 = 4*sin(x)*cos(x)/exp(2y). */ + __float128 exp_2t = expq (2 * t); + + __imag__ res = copysignq (1.0Q, __imag__ x); + __real__ res = 4 * sinrx * cosrx; + __imag__ x = fabsq (__imag__ x); + __imag__ x -= t; + __real__ res /= exp_2t; + if (__imag__ x > t) + { + /* Underflow (original imaginary part of x has absolute + value > 2t). */ + __real__ res /= exp_2t; + } + else + __real__ res /= expq (2 * __imag__ x); + } + else + { + __float128 sinhix, coshix; + if (fabsq (__imag__ x) > FLT128_MIN) + { + sinhix = sinhq (__imag__ x); + coshix = coshq (__imag__ x); + } + else + { + sinhix = __imag__ x; + coshix = 1.0Q; + } + + if (fabsq (sinhix) > fabsq (cosrx) * FLT128_EPSILON) + den = cosrx * cosrx + sinhix * sinhix; + else + den = cosrx * cosrx; + __real__ res = sinrx * cosrx / den; + __imag__ res = sinhix * coshix / den; + } + } + + return res; +} |