/* Return cosine of a complex 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 <math.h>

CFLOAT

M_DECL_FUNC (__cacos) (CFLOAT x)

{

  CFLOAT y;

  CFLOAT 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 = M_SUF (__casin) (x);

      __real__ res = (FLOAT) M_MLIT (M_PI_2) - __real__ y;

      if (__real__ res == 0)

	__real__ res = 0;

      __imag__ res = -__imag__ y;

    }

  else

    {

      __real__ y = -__imag__ x;

      __imag__ y = __real__ x;

      y = M_SUF (__kernel_casinh) (y, 1);

      __real__ res = __imag__ y;

      __imag__ res = __real__ y;

    }

  return res;

}

declare_mgen_alias (__cacos, cacos);