math/s_cacos.c

   1 /* Return cosine of complex double value.
   2    Copyright (C) 1997-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <complex.h>
  21 #include <math.h>
  22
  23 __complex__ double
  24 __cacos (__complex__ double x)
  25 {
  26   __complex__ double y;
  27   __complex__ double res;
  28   int rcls = fpclassify (__real__ x);
  29   int icls = fpclassify (__imag__ x);
  30
  31   if (rcls <= FP_INFINITE || icls <= FP_INFINITE
  32       || (rcls == FP_ZERO && icls == FP_ZERO))
  33     {
  34       y = __casin (x);
  35
  36       __real__ res = (double) M_PI_2 - __real__ y;
  37       __imag__ res = -__imag__ y;
  38     }
  39   else
  40     {
  41       __real__ y = -__imag__ x;
  42       __imag__ y = __real__ x;
  43
  44       y = __kernel_casinh (y, 1);
  45
  46       __real__ res = __imag__ y;
  47       __imag__ res = __real__ y;
  48     }
  49
  50   return res;
  51 }
  52 weak_alias (__cacos, cacos)
  53 #ifdef NO_LONG_DOUBLE
  54 strong_alias (__cacos, __cacosl)
  55 weak_alias (__cacos, cacosl)
  56 #endif