1 /*	$OpenBSD: s_ctanhf.c,v 1.2 2010/07/18 18:42:26 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 /*							ctanhf
19  *
20  *	Complex hyperbolic tangent
21  *
22  *
23  *
24  * SYNOPSIS:
25  *
26  * float complex ctanhf();
27  * float complex z, w;
28  *
29  * w = ctanhf (z);
30  *
31  *
32  *
33  * DESCRIPTION:
34  *
35  * tanh z = (sinh 2x  +  i sin 2y) / (cosh 2x + cos 2y) .
36  *
37  * ACCURACY:
38  *
39  *                      Relative error:
40  * arithmetic   domain     # trials      peak         rms
41  *    IEEE      -10,+10     30000       1.7e-14     2.4e-16
42  *
43  */
44 
45 #include <complex.h>
46 #include <math.h>
47 
48 float complex
49 ctanhf(float complex z)
50 {
51 	float complex w;
52 	float x, y, d;
53 
54 	x = crealf(z);
55 	y = cimagf(z);
56 	d = coshf (2.0f * x) + cosf (2.0f * y);
57 	w = sinhf (2.0f * x) / d  +  (sinf (2.0f * y) / d) * I;
58 	return (w);
59 }
60