/* Return cosine of complex double value.
   Copyright (C) 1997-2015 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 <math.h>

__complex__ double
__cacos (__complex__ double x)
{
  __complex__ double y;
  __complex__ double res;
  int rcls = fpclassify (__real__ x);
  int icls = fpclassify (__imag__ x);

  if (rcls <= FP_INFINITE || icls <= FP_INFINITE
      || (rcls == FP_ZERO && icls == FP_ZERO))
    {
      y = __casin (x);

      __real__ res = (double) M_PI_2 - __real__ y;
      if (__real__ res == 0.0)
	__real__ res = 0.0;
      __imag__ res = -__imag__ y;
    }
  else
    {
      __real__ y = -__imag__ x;
      __imag__ y = __real__ x;

      y = __kernel_casinh (y, 1);

      __real__ res = __imag__ y;
      __imag__ res = __real__ y;
    }

  return res;
}
weak_alias (__cacos, cacos)
#ifdef NO_LONG_DOUBLE
strong_alias (__cacos, __cacosl)
weak_alias (__cacos, cacosl)
#endif