/* $NetBSD: cproj.c,v 1.3 2010/09/20 17:51:38 christos Exp $ */ /*- * Copyright (c) 2010 The NetBSD Foundation, Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * * imported and modified include for newlib 2010/10/03 * Marco Atzeri <marco_atzeri@yahoo.it> */ /* FUNCTION <<cproj>>, <<cprojf>>--- Riemann sphere projection INDEX cproj INDEX cprojf SYNOPSIS #include <complex.h> double complex cproj(double complex <[z]>); float complex cprojf(float complex <[z]>); DESCRIPTION These functions compute a projection of <[z]> onto the Riemann sphere: <[z]> projects to <[z]> except that all complex infinities (even those with one infinite part and one NaN part) project to positive infinity on the real axis. If <[z]> has an infinite part, then <<cproj>>(<[z]>) is equivalent to INFINITY + I * copysign(0.0, cimag(z)) <<cprojf>> is identical to <<cproj>>, except that it performs its calculations on <<floats complex>>. RETURNS The cproj functions return the value of the projection onto the Riemann sphere. PORTABILITY <<cproj>> and <<cprojf>> are ISO C99 QUICKREF <<cproj>> and <<cprojf>> are ISO C99 */ #include <sys/cdefs.h> /*__RCSID("$NetBSD: cproj.c,v 1.3 2010/09/20 17:51:38 christos Exp $"); */ #include <complex.h> #include <math.h> #include "../common/fdlibm.h" /* * cproj(double complex z) * * These functions return the value of the projection (not stereographic!) * onto the Riemann sphere. * * z projects to z, except that all complex infinities (even those with one * infinite part and one NaN part) project to positive infinity on the real axis. * If z has an infinite part, then cproj(z) shall be equivalent to: * * INFINITY + I * copysign(0.0, cimag(z)) */ double complex cproj(double complex z) { double_complex w = { .z = z }; if (isinf(creal(z)) || isinf(cimag(z))) { #ifdef __INFINITY REAL_PART(w) = __INFINITY; #else REAL_PART(w) = INFINITY; #endif IMAG_PART(w) = copysign(0.0, cimag(z)); } return (w.z); }