1*05a0b428SJohn Marino /* $OpenBSD: s_ccos.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 /* ccos() 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 * double complex ccos(); 27*05a0b428SJohn Marino * double complex z, w; 28*05a0b428SJohn Marino * 29*05a0b428SJohn Marino * w = ccos (z); 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 * DEC -10,+10 8400 4.5e-17 1.3e-17 49*05a0b428SJohn Marino * IEEE -10,+10 30000 3.8e-16 1.0e-16 50*05a0b428SJohn Marino */ 51*05a0b428SJohn Marino 52*05a0b428SJohn Marino #include <complex.h> 53*05a0b428SJohn Marino #include <float.h> 54*05a0b428SJohn Marino #include <math.h> 55*05a0b428SJohn Marino 56*05a0b428SJohn Marino /* calculate cosh and sinh */ 57*05a0b428SJohn Marino 58*05a0b428SJohn Marino static void 59*05a0b428SJohn Marino _cchsh(double x, double *c, double *s) 60*05a0b428SJohn Marino { 61*05a0b428SJohn Marino double e, ei; 62*05a0b428SJohn Marino 63*05a0b428SJohn Marino if (fabs(x) <= 0.5) { 64*05a0b428SJohn Marino *c = cosh(x); 65*05a0b428SJohn Marino *s = sinh(x); 66*05a0b428SJohn Marino } 67*05a0b428SJohn Marino else { 68*05a0b428SJohn Marino e = exp(x); 69*05a0b428SJohn Marino ei = 0.5/e; 70*05a0b428SJohn Marino e = 0.5 * e; 71*05a0b428SJohn Marino *s = e - ei; 72*05a0b428SJohn Marino *c = e + ei; 73*05a0b428SJohn Marino } 74*05a0b428SJohn Marino } 75*05a0b428SJohn Marino 76*05a0b428SJohn Marino double complex 77*05a0b428SJohn Marino ccos(double complex z) 78*05a0b428SJohn Marino { 79*05a0b428SJohn Marino double complex w; 80*05a0b428SJohn Marino double ch, sh; 81*05a0b428SJohn Marino 82*05a0b428SJohn Marino _cchsh( cimag(z), &ch, &sh ); 83*05a0b428SJohn Marino w = cos(creal (z)) * ch - (sin (creal (z)) * sh) * I; 84*05a0b428SJohn Marino return (w); 85*05a0b428SJohn Marino } 86*05a0b428SJohn Marino 87*05a0b428SJohn Marino #if LDBL_MANT_DIG == DBL_MANT_DIG 88*05a0b428SJohn Marino __strong_alias(ccosl, ccos); 89*05a0b428SJohn Marino #endif /* LDBL_MANT_DIG == DBL_MANT_DIG */ 90