1 /* $NetBSD: cprojl.c,v 1.7 2014/10/10 00:48:18 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
29 #include <complex.h>
30 #include <math.h>
31
32 #include "../common/fdlibm.h"
33
34 /*
35 * cprojl(long double complex z)
36 *
37 * These functions return the value of the projection (not stereographic!)
38 * onto the Riemann sphere.
39 *
40 * z projects to z, except that all complex infinities (even those with one
41 * infinite part and one NaN part) project to positive infinity on the real axis.
42 * If z has an infinite part, then cproj(z) shall be equivalent to:
43 *
44 * INFINITY + (double complex) I * copysign(0.0, cimag(z))
45 */
46 long double complex
cprojl(long double complex z)47 cprojl(long double complex z)
48 {
49 long_double_complex w = { .z = z };
50
51 /*CONSTCOND*/
52 if (isinf(creall(z)) || isinf(cimagl(z))) {
53 #ifdef __INFINITY
54 REAL_PART(w) = HUGE_VAL;
55 #else
56 REAL_PART(w) = (long double) INFINITY;
57 #endif
58 IMAG_PART(w) = copysignl(0.0L, cimagl(z));
59 }
60
61 return (w.z);
62 }
63
