1/* Return cosine of complex double value.
2 Copyright (C) 1997-2016 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, see
18 <http://www.gnu.org/licenses/>. */
19
20#include <complex.h>
21#include <math.h>
22
23__complex__ double
24__cacos (__complex__ double x)
25{
26 __complex__ double y;
27 __complex__ double res;
28 int rcls = fpclassify (__real__ x);
29 int icls = fpclassify (__imag__ x);
30
31 if (rcls <= FP_INFINITE || icls <= FP_INFINITE
32 || (rcls == FP_ZERO && icls == FP_ZERO))
33 {
34 y = __casin (x);
35
36 __real__ res = (double) M_PI_2 - __real__ y;
37 if (__real__ res == 0.0)
38 __real__ res = 0.0;
39 __imag__ res = -__imag__ y;
40 }
41 else
42 {
43 __real__ y = -__imag__ x;
44 __imag__ y = __real__ x;
45
46 y = __kernel_casinh (y, 1);
47
48 __real__ res = __imag__ y;
49 __imag__ res = __real__ y;
50 }
51
52 return res;
53}
54weak_alias (__cacos, cacos)
55#ifdef NO_LONG_DOUBLE
56strong_alias (__cacos, __cacosl)
57weak_alias (__cacos, cacosl)
58#endif
59