s_ctanh.c revision 1.2 
1/*	$OpenBSD: s_ctanh.c,v 1.2 2011/07/08 19:25:31 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/* LINTLIBRARY */
19
20/*							ctanh
21 *
22 *	Complex hyperbolic tangent
23 *
24 *
25 *
26 * SYNOPSIS:
27 *
28 * double complex ctanh();
29 * double complex z, w;
30 *
31 * w = ctanh (z);
32 *
33 *
34 *
35 * DESCRIPTION:
36 *
37 * tanh z = (sinh 2x  +  i sin 2y) / (cosh 2x + cos 2y) .
38 *
39 * ACCURACY:
40 *
41 *                      Relative error:
42 * arithmetic   domain     # trials      peak         rms
43 *    IEEE      -10,+10     30000       1.7e-14     2.4e-16
44 *
45 */
46
47#include <sys/cdefs.h>
48#include <complex.h>
49#include <float.h>
50#include <math.h>
51
52double complex
53ctanh(double complex z)
54{
55	double complex w;
56	double x, y, d;
57
58	x = creal(z);
59	y = cimag(z);
60	d = cosh (2.0 * x) + cos (2.0 * y);
61	w = sinh (2.0 * x) / d  +  (sin (2.0 * y) / d) * I;
62	return (w);
63}
64
65#if	LDBL_MANT_DIG == 53
66#ifdef	lint
67/* PROTOLIB1 */
68long double complex ctanhl(long double complex);
69#else	/* lint */
70__weak_alias(ctanhl, ctanh);
71#endif	/* lint */
72#endif	/* LDBL_MANT_DIG == 53 */
73