1 /*	$OpenBSD: s_cacosf.c,v 1.2 2011/07/20 19:28:33 martynas 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 /*							cacosf()
19  *
20  *	Complex circular arc cosine
21  *
22  *
23  *
24  * SYNOPSIS:
25  *
26  * void cacosf();
27  * cmplxf z, w;
28  *
29  * cacosf( &z, &w );
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  *    IEEE      -10,+10     30000       9.2e-6       1.2e-6
46  *
47  */
48 
49 #include <complex.h>
50 #include <math.h>
51 
52 float complex
53 cacosf(float complex z)
54 {
55 	float complex w;
56 
57 	w = casinf( z );
58 	w = ((float)M_PI_2 - crealf (w)) - cimagf (w) * I;
59 	return (w);
60 }
61