1 /* $OpenBSD: s_ctanh.c,v 1.6 2013/07/03 04:46:36 espie 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 /* ctanh
19 *
20 * Complex hyperbolic tangent
21 *
22 *
23 *
24 * SYNOPSIS:
25 *
26 * double complex ctanh();
27 * double complex z, w;
28 *
29 * w = ctanh (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 <float.h>
47 #include <math.h>
48
49 double complex
ctanh(double complex z)50 ctanh(double complex z)
51 {
52 double complex w;
53 double x, y, d;
54
55 x = creal(z);
56 y = cimag(z);
57 d = cosh (2.0 * x) + cos (2.0 * y);
58 w = sinh (2.0 * x) / d + (sin (2.0 * y) / d) * I;
59 return (w);
60 }
61
62 #if LDBL_MANT_DIG == DBL_MANT_DIG
63 __strong_alias(ctanhl, ctanh);
64 #endif /* LDBL_MANT_DIG == DBL_MANT_DIG */
65