1 /* $OpenBSD: s_cacosl.c,v 1.3 2011/07/20 21:02:51 martynas Exp $ */ 2 3 /* 4 * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 /* cacosl() 20 * 21 * Complex circular arc cosine 22 * 23 * 24 * 25 * SYNOPSIS: 26 * 27 * long double complex cacosl(); 28 * long double complex z, w; 29 * 30 * w = cacosl( z ); 31 * 32 * 33 * 34 * DESCRIPTION: 35 * 36 * 37 * w = arccos z = PI/2 - arcsin z. 38 * 39 * 40 * 41 * 42 * ACCURACY: 43 * 44 * Relative error: 45 * arithmetic domain # trials peak rms 46 * DEC -10,+10 5200 1.6e-15 2.8e-16 47 * IEEE -10,+10 30000 1.8e-14 2.2e-15 48 */ 49 50 #include <complex.h> 51 #include <math.h> 52 53 static const long double PIO2L = 1.570796326794896619231321691639751442098585L; 54 55 long double complex 56 cacosl(long double complex z) 57 { 58 long double complex w; 59 60 w = casinl(z); 61 w = (PIO2L - creall(w)) - cimagl(w) * I; 62 return (w); 63 } 64