1/*	$NetBSD: cprojf.c,v 1.4 2011/03/02 13:24:43 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: cprojf.c,v 1.4 2011/03/02 13:24:43 christos Exp $");
30
31#include <complex.h>
32#include <math.h>
33
34#include "../src/math_private.h"
35
36/*
37 * cprojf(float 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
49float complex
50cprojf(float complex z)
51{
52	float_complex w = { .z = z };
53
54	/*CONSTCOND*/
55	if (isinf(crealf(z)) || isinf(cimagf(z))) {
56#ifdef __INFINITY
57		REAL_PART(w) = HUGE_VAL;
58#else
59		REAL_PART(w) = INFINITY;
60#endif
61		IMAG_PART(w) = copysignf(0.0, cimagf(z));
62	}
63
64	return (w.z);
65}
66