1 /* $OpenBSD: s_cacos.c,v 1.7 2016/09/12 19:47:02 guenther Exp $ */
2 /*
3 * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 /* cacos()
19 *
20 * Complex circular arc cosine
21 *
22 *
23 *
24 * SYNOPSIS:
25 *
26 * double complex cacos();
27 * double complex z, w;
28 *
29 * w = cacos (z);
30 *
31 *
32 *
33 * DESCRIPTION:
34 *
35 *
36 * w = arccos z = PI/2 - arcsin z.
37 *
38 *
39 *
40 *
41 * ACCURACY:
42 *
43 * Relative error:
44 * arithmetic domain # trials peak rms
45 * DEC -10,+10 5200 1.6e-15 2.8e-16
46 * IEEE -10,+10 30000 1.8e-14 2.2e-15
47 */
48
49 #include <complex.h>
50 #include <float.h>
51 #include <math.h>
52
53 double complex
cacos(double complex z)54 cacos(double complex z)
55 {
56 double complex w;
57
58 w = casin (z);
59 w = (M_PI_2 - creal (w)) - cimag (w) * I;
60 return (w);
61 }
62 DEF_STD(cacos);
63 LDBL_MAYBE_UNUSED_CLONE(cacos);
64