glibc/sysdeps/libm-ieee754/s_ctanhl.c

/* Complex hyperbole tangent for long 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 Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  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__ long double
__ctanhl (__complex__ long double x)
{
  __complex__ long double res;

  if (!isfinite (__real__ x) || !isfinite (__imag__ x))
    {
      if (__isinfl (__real__ x))
	{
	  __real__ res = __copysignl (1.0, __real__ x);
	  __imag__ res = __copysignl (0.0, __imag__ x);
	}
      else if (__imag__ x == 0.0)
	{
	  res = x;
	}
      else
	{
	  __real__ res = __nanl ("");
	  __imag__ res = __nanl ("");

#ifdef FE_INVALID
	  if (__isinfl (__imag__ x))
	    feraiseexcept (FE_INVALID);
#endif
	}
    }
  else
    {
      long double sin2ix, cos2ix;
      long double den;

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

      den = (__ieee754_coshl (2.0 * __real__ x) + cos2ix);

      __real__ res = __ieee754_sinhl (2.0 * __real__ x) / den;
      __imag__ res = sin2ix / den;
    }

  return res;
}
weak_alias (__ctanhl, ctanhl)