1 /* $NetBSD: cproj.c,v 1.3 2010/09/20 17:51:38 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2010 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 #include <sys/cdefs.h> 29 __RCSID("$NetBSD: cproj.c,v 1.3 2010/09/20 17:51:38 christos Exp $"); 30 31 #include <complex.h> 32 #include <math.h> 33 34 #include "../src/math_private.h" 35 36 /* 37 * cproj(double complex z) 38 * 39 * These functions return the value of the projection (not stereographic!) 40 * onto the Riemann sphere. 41 * 42 * z projects to z, except that all complex infinities (even those with one 43 * infinite part and one NaN part) project to positive infinity on the real axis. 44 * If z has an infinite part, then cproj(z) shall be equivalent to: 45 * 46 * INFINITY + I * copysign(0.0, cimag(z)) 47 */ 48 double complex 49 cproj(double complex z) 50 { 51 double_complex w = { .z = z }; 52 53 if (isinf(creal(z) || isinf(cimag(z)))) { 54 #ifdef __INFINITY 55 REAL_PART(w) = __INFINITY; 56 #else 57 REAL_PART(w) = INFINITY; 58 #endif 59 IMAG_PART(w) = copysign(0.0, cimag(z)); 60 } 61 62 return (w.z); 63 } 64