1 /*	$OpenBSD: s_ctanhl.c,v 1.2 2011/07/20 19:28:33 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 /*							ctanhl
20  *
21  *	Complex hyperbolic tangent
22  *
23  *
24  *
25  * SYNOPSIS:
26  *
27  * long double complex ctanhl();
28  * long double complex z, w;
29  *
30  * w = ctanhl (z);
31  *
32  *
33  *
34  * DESCRIPTION:
35  *
36  * tanh z = (sinh 2x  +  i sin 2y) / (cosh 2x + cos 2y) .
37  *
38  * ACCURACY:
39  *
40  *                      Relative error:
41  * arithmetic   domain     # trials      peak         rms
42  *    IEEE      -10,+10     30000       1.7e-14     2.4e-16
43  *
44  */
45 
46 #include <complex.h>
47 #include <math.h>
48 
49 long double complex
50 ctanhl(long double complex z)
51 {
52 	long double complex w;
53 	long double x, y, d;
54 
55 	x = creall(z);
56 	y = cimagl(z);
57 	d = coshl(2.0L * x) + cosl(2.0L * y);
58 	w = sinhl(2.0L * x) / d + (sinl(2.0L * y) / d) * I;
59 	return (w);
60 }
61