1/* Complex hyperbole tangent for double.
2   Copyright (C) 1997 Free Software Foundation, Inc.
3   This file is part of the GNU C Library.
4   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
5
6   The GNU C Library is free software; you can redistribute it and/or
7   modify it under the terms of the GNU Lesser General Public
8   License as published by the Free Software Foundation; either
9   version 2.1 of the License, or (at your option) any later version.
10
11   The GNU C Library is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   Lesser General Public License for more details.
15
16   You should have received a copy of the GNU Lesser General Public
17   License along with the GNU C Library; if not, write to the Free
18   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19   02111-1307 USA.  */
20
21#include <complex.h>
22#include <fenv.h>
23#include <math.h>
24
25#include "math_private.h"
26
27
28__complex__ double
29__ctanh (__complex__ double x)
30{
31  __complex__ double res;
32
33  if (!isfinite (__real__ x) || !isfinite (__imag__ x))
34    {
35      if (__isinf (__real__ x))
36	{
37	  __real__ res = copysign (1.0, __real__ x);
38	  __imag__ res = copysign (0.0, __imag__ x);
39	}
40      else if (__imag__ x == 0.0)
41	{
42	  res = x;
43	}
44      else
45	{
46	  __real__ res = nan ("");
47	  __imag__ res = nan ("");
48
49#ifdef FE_INVALID
50	  if (__isinf (__imag__ x))
51	    feraiseexcept (FE_INVALID);
52#endif
53	}
54    }
55  else
56    {
57      double sin2ix, cos2ix;
58      double den;
59
60      sincos (2.0 * __imag__ x, &sin2ix, &cos2ix);
61
62      den = (cosh (2.0 * __real__ x) + cos2ix);
63
64      __real__ res = sinh (2.0 * __real__ x) / den;
65      __imag__ res = sin2ix / den;
66    }
67
68  return res;
69}
70weak_alias (__ctanh, ctanh)
71#ifdef NO_LONG_DOUBLE
72strong_alias (__ctanh, __ctanhl)
73weak_alias (__ctanh, ctanhl)
74#endif
75