| /* Complex tangent function for a complex float type. |
| Copyright (C) 1997-2018 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> |
| |
| CFLOAT |
| M_DECL_FUNC (__ctan) (CFLOAT x) |
| { |
| CFLOAT res; |
| |
| if (__glibc_unlikely (!isfinite (__real__ x) || !isfinite (__imag__ x))) |
| { |
| if (isinf (__imag__ x)) |
| { |
| if (isfinite (__real__ x) && M_FABS (__real__ x) > 1) |
| { |
| FLOAT sinrx, cosrx; |
| M_SINCOS (__real__ x, &sinrx, &cosrx); |
| __real__ res = M_COPYSIGN (0, sinrx * cosrx); |
| } |
| else |
| __real__ res = M_COPYSIGN (0, __real__ x); |
| __imag__ res = M_COPYSIGN (1, __imag__ x); |
| } |
| else if (__real__ x == 0) |
| { |
| res = x; |
| } |
| else |
| { |
| __real__ res = M_NAN; |
| if (__imag__ x == 0) |
| __imag__ res = __imag__ x; |
| else |
| __imag__ res = M_NAN; |
| |
| if (isinf (__real__ x)) |
| feraiseexcept (FE_INVALID); |
| } |
| } |
| else |
| { |
| FLOAT sinrx, cosrx; |
| FLOAT den; |
| const int t = (int) ((M_MAX_EXP - 1) * M_MLIT (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 (M_FABS (__real__ x) > M_MIN)) |
| { |
| M_SINCOS (__real__ x, &sinrx, &cosrx); |
| } |
| else |
| { |
| sinrx = __real__ x; |
| cosrx = 1; |
| } |
| |
| if (M_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). */ |
| FLOAT exp_2t = M_EXP (2 * t); |
| |
| __imag__ res = M_COPYSIGN (1, __imag__ x); |
| __real__ res = 4 * sinrx * cosrx; |
| __imag__ x = M_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 /= M_EXP (2 * __imag__ x); |
| } |
| else |
| { |
| FLOAT sinhix, coshix; |
| if (M_FABS (__imag__ x) > M_MIN) |
| { |
| sinhix = M_SINH (__imag__ x); |
| coshix = M_COSH (__imag__ x); |
| } |
| else |
| { |
| sinhix = __imag__ x; |
| coshix = 1; |
| } |
| |
| if (M_FABS (sinhix) > M_FABS (cosrx) * M_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; |
| } |
| |
| declare_mgen_alias (__ctan, ctan) |