1/* Return arc hyperbole cosine 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
25__complex__ long double
26__cacoshl (__complex__ long double x)
27{
28  __complex__ long double res;
29  int rcls = fpclassify (__real__ x);
30  int icls = fpclassify (__imag__ x);
31
32  if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
33    {
34      if (icls == FP_INFINITE)
35	{
36	  __real__ res = HUGE_VALL;
37
38	  if (rcls == FP_NAN)
39	    __imag__ res = nanl ("");
40	  else
41	    __imag__ res = copysignl ((rcls == FP_INFINITE
42					 ? (__real__ x < 0.0
43					    ? M_PIl - M_PI_4l : M_PI_4l)
44					 : M_PI_2l), __imag__ x);
45	}
46      else if (rcls == FP_INFINITE)
47	{
48	  __real__ res = HUGE_VALL;
49
50	  if (icls >= FP_ZERO)
51	    __imag__ res = copysignl (signbit (__real__ x) ? M_PIl : 0.0,
52					__imag__ x);
53	  else
54	    __imag__ res = nanl ("");
55	}
56      else
57	{
58	  __real__ res = nanl ("");
59	  __imag__ res = nanl ("");
60	}
61    }
62  else if (rcls == FP_ZERO && icls == FP_ZERO)
63    {
64      __real__ res = 0.0;
65      __imag__ res = copysignl (M_PI_2l, __imag__ x);
66    }
67  else
68    {
69      __complex__ long double y;
70
71      __real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) - 1.0;
72      __imag__ y = 2.0 * __real__ x * __imag__ x;
73
74      y = __csqrtl (y);
75
76      __real__ y += __real__ x;
77      __imag__ y += __imag__ x;
78
79      res = __clogl (y);
80    }
81
82  return res;
83}
84weak_alias (__cacoshl, cacoshl)
85