1*05a0b428SJohn Marino /* $OpenBSD: s_ctanh.c,v 1.6 2013/07/03 04:46:36 espie Exp $ */
2*05a0b428SJohn Marino /*
3*05a0b428SJohn Marino * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
4*05a0b428SJohn Marino *
5*05a0b428SJohn Marino * Permission to use, copy, modify, and distribute this software for any
6*05a0b428SJohn Marino * purpose with or without fee is hereby granted, provided that the above
7*05a0b428SJohn Marino * copyright notice and this permission notice appear in all copies.
8*05a0b428SJohn Marino *
9*05a0b428SJohn Marino * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10*05a0b428SJohn Marino * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11*05a0b428SJohn Marino * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12*05a0b428SJohn Marino * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13*05a0b428SJohn Marino * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14*05a0b428SJohn Marino * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15*05a0b428SJohn Marino * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16*05a0b428SJohn Marino */
17*05a0b428SJohn Marino
18*05a0b428SJohn Marino /* ctanh
19*05a0b428SJohn Marino *
20*05a0b428SJohn Marino * Complex hyperbolic tangent
21*05a0b428SJohn Marino *
22*05a0b428SJohn Marino *
23*05a0b428SJohn Marino *
24*05a0b428SJohn Marino * SYNOPSIS:
25*05a0b428SJohn Marino *
26*05a0b428SJohn Marino * double complex ctanh();
27*05a0b428SJohn Marino * double complex z, w;
28*05a0b428SJohn Marino *
29*05a0b428SJohn Marino * w = ctanh (z);
30*05a0b428SJohn Marino *
31*05a0b428SJohn Marino *
32*05a0b428SJohn Marino *
33*05a0b428SJohn Marino * DESCRIPTION:
34*05a0b428SJohn Marino *
35*05a0b428SJohn Marino * tanh z = (sinh 2x + i sin 2y) / (cosh 2x + cos 2y) .
36*05a0b428SJohn Marino *
37*05a0b428SJohn Marino * ACCURACY:
38*05a0b428SJohn Marino *
39*05a0b428SJohn Marino * Relative error:
40*05a0b428SJohn Marino * arithmetic domain # trials peak rms
41*05a0b428SJohn Marino * IEEE -10,+10 30000 1.7e-14 2.4e-16
42*05a0b428SJohn Marino *
43*05a0b428SJohn Marino */
44*05a0b428SJohn Marino
45*05a0b428SJohn Marino #include <complex.h>
46*05a0b428SJohn Marino #include <float.h>
47*05a0b428SJohn Marino #include <math.h>
48*05a0b428SJohn Marino
49*05a0b428SJohn Marino double complex
ctanh(double complex z)50*05a0b428SJohn Marino ctanh(double complex z)
51*05a0b428SJohn Marino {
52*05a0b428SJohn Marino double complex w;
53*05a0b428SJohn Marino double x, y, d;
54*05a0b428SJohn Marino
55*05a0b428SJohn Marino x = creal(z);
56*05a0b428SJohn Marino y = cimag(z);
57*05a0b428SJohn Marino d = cosh (2.0 * x) + cos (2.0 * y);
58*05a0b428SJohn Marino w = sinh (2.0 * x) / d + (sin (2.0 * y) / d) * I;
59*05a0b428SJohn Marino return (w);
60*05a0b428SJohn Marino }
61*05a0b428SJohn Marino
62*05a0b428SJohn Marino #if LDBL_MANT_DIG == DBL_MANT_DIG
63*05a0b428SJohn Marino __strong_alias(ctanhl, ctanh);
64*05a0b428SJohn Marino #endif /* LDBL_MANT_DIG == DBL_MANT_DIG */
65