1/* Return arc hyperbole tangent for long double value.
2   Copyright (C) 1997, 1998 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 <math.h>
23
24#include "math_private.h"
25
26
27__complex__ long double
28__catanhl (__complex__ long double x)
29{
30  __complex__ long double res;
31  int rcls = fpclassify (__real__ x);
32  int icls = fpclassify (__imag__ x);
33
34  if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
35    {
36      if (icls == FP_INFINITE)
37	{
38	  __real__ res = copysignl (0.0, __real__ x);
39	  __imag__ res = copysignl (M_PI_2l, __imag__ x);
40	}
41      else if (rcls == FP_INFINITE || rcls == FP_ZERO)
42	{
43	  __real__ res = copysignl (0.0, __real__ x);
44	  if (icls >= FP_ZERO)
45	    __imag__ res = copysignl (M_PI_2l, __imag__ x);
46	  else
47	    __imag__ res = nanl ("");
48	}
49      else
50	{
51	  __real__ res = nanl ("");
52	  __imag__ res = nanl ("");
53	}
54    }
55  else if (rcls == FP_ZERO && icls == FP_ZERO)
56    {
57      res = x;
58    }
59  else
60    {
61      long double i2, num, den;
62
63      i2 = __imag__ x * __imag__ x;
64
65      num = 1.0 + __real__ x;
66      num = i2 + num * num;
67
68      den = 1.0 - __real__ x;
69      den = i2 + den * den;
70
71      __real__ res = 0.25 * (logl (num) - logl (den));
72
73      den = 1 - __real__ x * __real__ x - i2;
74
75      __imag__ res = 0.5 * atan2l (2.0 * __imag__ x, den);
76    }
77
78  return res;
79}
80weak_alias (__catanhl, catanhl)
81