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/* Return arc hyperbole tangent for __float128 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 "quadmath-imp.h"

__complex128

catanhq (__complex128 x)

{

  __complex128 res;

  int rcls = fpclassifyq (__real__ x);

  int icls = fpclassifyq (__imag__ x);

  if (rcls <= QUADFP_INFINITE || icls <= QUADFP_INFINITE)

    {

      if (icls == QUADFP_INFINITE)

        {

          __real__ res = copysignq (0.0, __real__ x);

          __imag__ res = copysignq (M_PI_2q, __imag__ x);

        }

      else if (rcls == QUADFP_INFINITE || rcls == QUADFP_ZERO)

        {

          __real__ res = copysignq (0.0, __real__ x);

          if (icls >= QUADFP_ZERO)

            __imag__ res = copysignq (M_PI_2q, __imag__ x);

          else

            __imag__ res = nanq ("");

        }

      else

        {

          __real__ res = nanq ("");

          __imag__ res = nanq ("");

        }

    }

  else if (rcls == QUADFP_ZERO && icls == QUADFP_ZERO)

    {

      res = x;

    }

  else

    {

      __float128 i2, num, den;

      i2 = __imag__ x * __imag__ x;

      num = 1.0 + __real__ x;

      num = i2 + num * num;

      den = 1.0 - __real__ x;

      den = i2 + den * den;

      __real__ res = 0.25 * (logq (num) - logq (den));

      den = 1 - __real__ x * __real__ x - i2;

      __imag__ res = 0.5 * atan2q (2.0 * __imag__ x, den);

    }

  return res;

}