1 /* $OpenBSD: s_cacosl.c,v 1.3 2011/07/20 21:02:51 martynas Exp $ */
2
3 /*
4 * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 /* cacosl()
20 *
21 * Complex circular arc cosine
22 *
23 *
24 *
25 * SYNOPSIS:
26 *
27 * long double complex cacosl();
28 * long double complex z, w;
29 *
30 * w = cacosl( z );
31 *
32 *
33 *
34 * DESCRIPTION:
35 *
36 *
37 * w = arccos z = PI/2 - arcsin z.
38 *
39 *
40 *
41 *
42 * ACCURACY:
43 *
44 * Relative error:
45 * arithmetic domain # trials peak rms
46 * DEC -10,+10 5200 1.6e-15 2.8e-16
47 * IEEE -10,+10 30000 1.8e-14 2.2e-15
48 */
49
50 #include <complex.h>
51 #include <math.h>
52
53 static const long double PIO2L = 1.570796326794896619231321691639751442098585L;
54
55 long double complex
cacosl(long double complex z)56 cacosl(long double complex z)
57 {
58 long double complex w;
59
60 w = casinl(z);
61 w = (PIO2L - creall(w)) - cimagl(w) * I;
62 return (w);
63 }
64