/* Return arc hyperbole cosine for long double value.
   Copyright (C) 1997, 1998 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <complex.h>
#include <math.h>


__complex__ long double
__cacoshl (__complex__ long double x)
{
  __complex__ long double res;
  int rcls = fpclassify (__real__ x);
  int icls = fpclassify (__imag__ x);

  if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
    {
      if (icls == FP_INFINITE)
        {
          __real__ res = HUGE_VALL;

          if (rcls == FP_NAN)
            __imag__ res = nanl ("");
          else
            __imag__ res = copysignl ((rcls == FP_INFINITE
                                         ? (__real__ x < 0.0
                                            ? M_PIl - M_PI_4l : M_PI_4l)
                                         : M_PI_2l), __imag__ x);
        }
      else if (rcls == FP_INFINITE)
        {
          __real__ res = HUGE_VALL;

          if (icls >= FP_ZERO)
            __imag__ res = copysignl (signbit (__real__ x) ? M_PIl : 0.0,
                                        __imag__ x);
          else
            __imag__ res = nanl ("");
        }
      else
        {
          __real__ res = nanl ("");
          __imag__ res = nanl ("");
        }
    }
  else if (rcls == FP_ZERO && icls == FP_ZERO)
    {
      __real__ res = 0.0;
      __imag__ res = copysignl (M_PI_2l, __imag__ x);
    }
  else
    {
      __complex__ long double y;

      __real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) - 1.0;
      __imag__ y = 2.0 * __real__ x * __imag__ x;

      y = __csqrtl (y);

      __real__ y += __real__ x;
      __imag__ y += __imag__ x;

      res = __clogl (y);
    }

  return res;
}
weak_alias (__cacoshl, cacoshl)