1 /* $OpenBSD: s_ccos.c,v 1.2 2011/07/08 19:25:31 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 /* LINTLIBRARY */ 19 20 /* ccos() 21 * 22 * Complex circular cosine 23 * 24 * 25 * 26 * SYNOPSIS: 27 * 28 * double complex ccos(); 29 * double complex z, w; 30 * 31 * w = ccos (z); 32 * 33 * 34 * 35 * DESCRIPTION: 36 * 37 * If 38 * z = x + iy, 39 * 40 * then 41 * 42 * w = cos x cosh y - i sin x sinh y. 43 * 44 * 45 * 46 * ACCURACY: 47 * 48 * Relative error: 49 * arithmetic domain # trials peak rms 50 * DEC -10,+10 8400 4.5e-17 1.3e-17 51 * IEEE -10,+10 30000 3.8e-16 1.0e-16 52 */ 53 54 #include <sys/cdefs.h> 55 #include <complex.h> 56 #include <float.h> 57 #include <math.h> 58 59 /* calculate cosh and sinh */ 60 61 static void 62 _cchsh(double x, double *c, double *s) 63 { 64 double e, ei; 65 66 if (fabs(x) <= 0.5) { 67 *c = cosh(x); 68 *s = sinh(x); 69 } 70 else { 71 e = exp(x); 72 ei = 0.5/e; 73 e = 0.5 * e; 74 *s = e - ei; 75 *c = e + ei; 76 } 77 } 78 79 double complex 80 ccos(double complex z) 81 { 82 double complex w; 83 double ch, sh; 84 85 _cchsh( cimag(z), &ch, &sh ); 86 w = cos(creal (z)) * ch - (sin (creal (z)) * sh) * I; 87 return (w); 88 } 89 90 #if LDBL_MANT_DIG == 53 91 #ifdef lint 92 /* PROTOLIB1 */ 93 long double complex ccosl(long double complex); 94 #else /* lint */ 95 __weak_alias(ccosl, ccos); 96 #endif /* lint */ 97 #endif /* LDBL_MANT_DIG == 53 */ 98