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Diffstat (limited to 'math/s_ctan_template.c')
| -rw-r--r-- | math/s_ctan_template.c | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/math/s_ctan_template.c b/math/s_ctan_template.c new file mode 100644 index 0000000..8e8bf2e --- /dev/null +++ b/math/s_ctan_template.c @@ -0,0 +1,129 @@ +/* Complex tangent function for double. + Copyright (C) 1997-2016 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 <complex.h> +#include <fenv.h> +#include <math.h> +#include <math_private.h> +#include <float.h> + +__complex__ double +__ctan (__complex__ double x) +{ + __complex__ double res; + + if (__glibc_unlikely (!isfinite (__real__ x) || !isfinite (__imag__ x))) + { + if (isinf (__imag__ x)) + { + if (isfinite (__real__ x) && fabs (__real__ x) > 1.0) + { + double sinrx, cosrx; + __sincos (__real__ x, &sinrx, &cosrx); + __real__ res = __copysign (0.0, sinrx * cosrx); + } + else + __real__ res = __copysign (0.0, __real__ x); + __imag__ res = __copysign (1.0, __imag__ x); + } + else if (__real__ x == 0.0) + { + res = x; + } + else + { + __real__ res = __nan (""); + __imag__ res = __nan (""); + + if (isinf (__real__ x)) + feraiseexcept (FE_INVALID); + } + } + else + { + double sinrx, cosrx; + double den; + const int t = (int) ((DBL_MAX_EXP - 1) * M_LN2 / 2); + + /* 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 (__glibc_likely (fabs (__real__ x) > DBL_MIN)) + { + __sincos (__real__ x, &sinrx, &cosrx); + } + else + { + sinrx = __real__ x; + cosrx = 1.0; + } + + if (fabs (__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). */ + double exp_2t = __ieee754_exp (2 * t); + + __imag__ res = __copysign (1.0, __imag__ x); + __real__ res = 4 * sinrx * cosrx; + __imag__ x = fabs (__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 /= __ieee754_exp (2 * __imag__ x); + } + else + { + double sinhix, coshix; + if (fabs (__imag__ x) > DBL_MIN) + { + sinhix = __ieee754_sinh (__imag__ x); + coshix = __ieee754_cosh (__imag__ x); + } + else + { + sinhix = __imag__ x; + coshix = 1.0; + } + + if (fabs (sinhix) > fabs (cosrx) * DBL_EPSILON) + den = cosrx * cosrx + sinhix * sinhix; + else + den = cosrx * cosrx; + __real__ res = sinrx * cosrx / den; + __imag__ res = sinhix * coshix / den; + } + math_check_force_underflow_complex (res); + } + + return res; +} +weak_alias (__ctan, ctan) +#ifdef NO_LONG_DOUBLE +strong_alias (__ctan, __ctanl) +weak_alias (__ctan, ctanl) +#endif |