1/* Return arc hyperbole tangent for __float128 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 "quadmath-imp.h"
22
23
24__complex128
25catanhq (__complex128 x)
26{
27  __complex128 res;
28  int rcls = fpclassifyq (__real__ x);
29  int icls = fpclassifyq (__imag__ x);
30
31  if (rcls <= QUADFP_INFINITE || icls <= QUADFP_INFINITE)
32    {
33      if (icls == QUADFP_INFINITE)
34	{
35	  __real__ res = copysignq (0.0, __real__ x);
36	  __imag__ res = copysignq (M_PI_2q, __imag__ x);
37	}
38      else if (rcls == QUADFP_INFINITE || rcls == QUADFP_ZERO)
39	{
40	  __real__ res = copysignq (0.0, __real__ x);
41	  if (icls >= QUADFP_ZERO)
42	    __imag__ res = copysignq (M_PI_2q, __imag__ x);
43	  else
44	    __imag__ res = nanq ("");
45	}
46      else
47	{
48	  __real__ res = nanq ("");
49	  __imag__ res = nanq ("");
50	}
51    }
52  else if (rcls == QUADFP_ZERO && icls == QUADFP_ZERO)
53    {
54      res = x;
55    }
56  else
57    {
58      __float128 i2, num, den;
59
60      i2 = __imag__ x * __imag__ x;
61
62      num = 1.0 + __real__ x;
63      num = i2 + num * num;
64
65      den = 1.0 - __real__ x;
66      den = i2 + den * den;
67
68      __real__ res = 0.25 * (logq (num) - logq (den));
69
70      den = 1 - __real__ x * __real__ x - i2;
71
72      __imag__ res = 0.5 * atan2q (2.0 * __imag__ x, den);
73    }
74
75  return res;
76}
77