1/* Return arc hyperbole cosine for float value.
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 <math.h>
23
24#include "math_private.h"
25
26__complex__ float
27__cacoshf (__complex__ float x)
28{
29  __complex__ float res;
30  int rcls = fpclassify (__real__ x);
31  int icls = fpclassify (__imag__ x);
32
33  if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
34    {
35      if (icls == FP_INFINITE)
36	{
37	  __real__ res = HUGE_VALF;
38
39	  if (rcls == FP_NAN)
40	    __imag__ res = nanf ("");
41	  else
42	    __imag__ res = copysignf ((rcls == FP_INFINITE
43					 ? (__real__ x < 0.0
44					    ? M_PI - M_PI_4 : M_PI_4)
45					 : M_PI_2), __imag__ x);
46	}
47      else if (rcls == FP_INFINITE)
48	{
49	  __real__ res = HUGE_VALF;
50
51	  if (icls >= FP_ZERO)
52	    __imag__ res = copysignf (signbit (__real__ x) ? M_PI : 0.0,
53					__imag__ x);
54	  else
55	    __imag__ res = nanf ("");
56	}
57      else
58	{
59	  __real__ res = nanf ("");
60	  __imag__ res = nanf ("");
61	}
62    }
63  else if (rcls == FP_ZERO && icls == FP_ZERO)
64    {
65      __real__ res = 0.0;
66      __imag__ res = copysignf (M_PI_2, __imag__ x);
67    }
68  else
69    {
70#if 1
71      __complex__ float y;
72
73      __real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) - 1.0;
74      __imag__ y = 2.0 * __real__ x * __imag__ x;
75
76      y = __csqrtf (y);
77
78      __real__ y += __real__ x;
79      __imag__ y += __imag__ x;
80
81      res = __clogf (y);
82#else
83      float re2 = __real__ x * __real__ x;
84      float im2 = __imag__ x * __imag__ x;
85      float sq = re2 - im2 - 1.0;
86      float ro = sqrtf (sq * sq + 4 * re2 * im2);
87      float a = sqrtf ((sq + ro) / 2.0);
88      float b = sqrtf ((-sq + ro) / 2.0);
89
90      __real__ res = 0.5 * logf (re2 + __real__ x * 2 * a
91					   + im2 + __imag__ x * 2 * b
92					   + ro);
93      __imag__ res = atan2f (__imag__ x + b, __real__ x + a);
94#endif
95    }
96
97  return res;
98}
99#ifndef __cacoshf
100weak_alias (__cacoshf, cacoshf)
101#endif
102