1*05a0b428SJohn Marino /* $OpenBSD: s_ccosf.c,v 1.2 2010/07/18 18:42:26 guenther 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 /* ccosf()
19*05a0b428SJohn Marino *
20*05a0b428SJohn Marino * Complex circular cosine
21*05a0b428SJohn Marino *
22*05a0b428SJohn Marino *
23*05a0b428SJohn Marino *
24*05a0b428SJohn Marino * SYNOPSIS:
25*05a0b428SJohn Marino *
26*05a0b428SJohn Marino * void ccosf();
27*05a0b428SJohn Marino * cmplxf z, w;
28*05a0b428SJohn Marino *
29*05a0b428SJohn Marino * ccosf( &z, &w );
30*05a0b428SJohn Marino *
31*05a0b428SJohn Marino *
32*05a0b428SJohn Marino *
33*05a0b428SJohn Marino * DESCRIPTION:
34*05a0b428SJohn Marino *
35*05a0b428SJohn Marino * If
36*05a0b428SJohn Marino * z = x + iy,
37*05a0b428SJohn Marino *
38*05a0b428SJohn Marino * then
39*05a0b428SJohn Marino *
40*05a0b428SJohn Marino * w = cos x cosh y - i sin x sinh y.
41*05a0b428SJohn Marino *
42*05a0b428SJohn Marino *
43*05a0b428SJohn Marino *
44*05a0b428SJohn Marino * ACCURACY:
45*05a0b428SJohn Marino *
46*05a0b428SJohn Marino * Relative error:
47*05a0b428SJohn Marino * arithmetic domain # trials peak rms
48*05a0b428SJohn Marino * IEEE -10,+10 30000 1.8e-7 5.5e-8
49*05a0b428SJohn Marino */
50*05a0b428SJohn Marino
51*05a0b428SJohn Marino #include <complex.h>
52*05a0b428SJohn Marino #include <math.h>
53*05a0b428SJohn Marino
54*05a0b428SJohn Marino /* calculate cosh and sinh */
55*05a0b428SJohn Marino
56*05a0b428SJohn Marino static void
_cchshf(float xx,float * c,float * s)57*05a0b428SJohn Marino _cchshf(float xx, float *c, float *s)
58*05a0b428SJohn Marino {
59*05a0b428SJohn Marino float x, e, ei;
60*05a0b428SJohn Marino
61*05a0b428SJohn Marino x = xx;
62*05a0b428SJohn Marino if(fabsf(x) <= 0.5f) {
63*05a0b428SJohn Marino *c = coshf(x);
64*05a0b428SJohn Marino *s = sinhf(x);
65*05a0b428SJohn Marino }
66*05a0b428SJohn Marino else {
67*05a0b428SJohn Marino e = expf(x);
68*05a0b428SJohn Marino ei = 0.5f/e;
69*05a0b428SJohn Marino e = 0.5f * e;
70*05a0b428SJohn Marino *s = e - ei;
71*05a0b428SJohn Marino *c = e + ei;
72*05a0b428SJohn Marino }
73*05a0b428SJohn Marino }
74*05a0b428SJohn Marino
75*05a0b428SJohn Marino float complex
ccosf(float complex z)76*05a0b428SJohn Marino ccosf(float complex z)
77*05a0b428SJohn Marino {
78*05a0b428SJohn Marino float complex w;
79*05a0b428SJohn Marino float ch, sh;
80*05a0b428SJohn Marino
81*05a0b428SJohn Marino _cchshf( cimagf(z), &ch, &sh );
82*05a0b428SJohn Marino w = cosf( crealf(z) ) * ch + ( -sinf( crealf(z) ) * sh) * I;
83*05a0b428SJohn Marino return (w);
84*05a0b428SJohn Marino }
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