1 /* Return arc hyperbole cosine for float value.
2 Copyright (C) 1997, 2006 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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.
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.
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
24 #include "math_private.h"
27 __cacoshf (__complex__ float x)
29 __complex__ float res;
30 int rcls = fpclassify (__real__ x);
31 int icls = fpclassify (__imag__ x);
33 if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
35 if (icls == FP_INFINITE)
37 __real__ res = HUGE_VALF;
40 __imag__ res = __nanf ("");
42 __imag__ res = __copysignf ((rcls == FP_INFINITE
44 ? M_PI - M_PI_4 : M_PI_4)
45 : M_PI_2), __imag__ x);
47 else if (rcls == FP_INFINITE)
49 __real__ res = HUGE_VALF;
52 __imag__ res = __copysignf (signbit (__real__ x) ? M_PI : 0.0,
55 __imag__ res = __nanf ("");
59 __real__ res = __nanf ("");
60 __imag__ res = __nanf ("");
63 else if (rcls == FP_ZERO && icls == FP_ZERO)
66 __imag__ res = __copysignf (M_PI_2, __imag__ x);
73 __real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) - 1.0;
74 __imag__ y = 2.0 * __real__ x * __imag__ x;
81 __real__ y += __real__ x;
82 __imag__ y += __imag__ x;
86 float re2 = __real__ x * __real__ x;
87 float im2 = __imag__ x * __imag__ x;
88 float sq = re2 - im2 - 1.0;
89 float ro = __ieee754_sqrtf (sq * sq + 4 * re2 * im2);
90 float a = __ieee754_sqrtf ((sq + ro) / 2.0);
91 float b = __ieee754_sqrtf ((-sq + ro) / 2.0);
93 __real__ res = 0.5 * __ieee754_logf (re2 + __real__ x * 2 * a
94 + im2 + __imag__ x * 2 * b
96 __imag__ res = __ieee754_atan2f (__imag__ x + b, __real__ x + a);
99 /* We have to use the positive branch. */
100 if (__real__ res < 0.0)
107 weak_alias (__cacoshf, cacoshf)