1 /* $OpenBSD: s_csinf.c,v 1.1 2008/09/07 20:36:09 martynas 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 /* csinf() 19 * 20 * Complex circular sine 21 * 22 * 23 * 24 * SYNOPSIS: 25 * 26 * void csinf(); 27 * cmplxf z, w; 28 * 29 * csinf( &z, &w ); 30 * 31 * 32 * 33 * DESCRIPTION: 34 * 35 * If 36 * z = x + iy, 37 * 38 * then 39 * 40 * w = sin x cosh y + i cos x sinh y. 41 * 42 * 43 * 44 * ACCURACY: 45 * 46 * Relative error: 47 * arithmetic domain # trials peak rms 48 * IEEE -10,+10 30000 1.9e-7 5.5e-8 49 * 50 */ 51 52 #include <complex.h> 53 #include <math.h> 54 55 /* calculate cosh and sinh */ 56 57 static void 58 cchshf(float xx, float *c, float *s) 59 { 60 float x, e, ei; 61 62 x = xx; 63 if(fabsf(x) <= 0.5f) { 64 *c = coshf(x); 65 *s = sinhf(x); 66 } 67 else { 68 e = expf(x); 69 ei = 0.5f/e; 70 e = 0.5f * e; 71 *s = e - ei; 72 *c = e + ei; 73 } 74 } 75 76 float complex 77 csinf(float complex z) 78 { 79 float complex w; 80 float ch, sh; 81 82 cchshf((float) cimag(z), &ch, &sh); 83 w = sinf(creal(z)) * ch + (cosf(creal(z)) * sh) * I; 84 return (w); 85 } 86