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/* Complex hyperbole tangent for double.

   Copyright (C) 1997 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 <fenv.h>

#include <math.h>

#include "math_private.h"

__complex__ double

__ctanh (__complex__ double x)

{

  __complex__ double res;

  if (!isfinite (__real__ x) || !isfinite (__imag__ x))

    {

      if (__isinf (__real__ x))

        {

          __real__ res = __copysign (1.0, __real__ x);

          __imag__ res = __copysign (0.0, __imag__ x);

        }

      else if (__imag__ x == 0.0)

        {

          res = x;

        }

      else

        {

          __real__ res = __nan ("");

          __imag__ res = __nan ("");

#ifdef FE_INVALID

          if (__isinf (__imag__ x))

            feraiseexcept (FE_INVALID);

#endif

        }

    }

  else

    {

      double sin2ix, cos2ix;

      double den;

      __sincos (2.0 * __imag__ x, &sin2ix, &cos2ix);

      den = (__ieee754_cosh (2.0 * __real__ x) + cos2ix);

      __real__ res = __ieee754_sinh (2.0 * __real__ x) / den;

      __imag__ res = sin2ix / den;

    }

  return res;

}

weak_alias (__ctanh, ctanh)

#ifdef NO_LONG_DOUBLE

strong_alias (__ctanh, __ctanhl)

weak_alias (__ctanh, ctanhl)

#endif