1 /* $NetBSD: cproj.c,v 1.5 2011/11/02 02:34:56 christos Exp $ */
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32 #include "../src/math_private.h"
35 * cproj(double complex z)
37 * These functions return the value of the projection (not stereographic!)
38 * onto the Riemann sphere.
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:
44 * INFINITY + I * copysign(0.0, cimag(z))
47 cproj(double complex z)
49 double_complex w = { .z = z };
52 if (isinf(creal(z)) || isinf(cimag(z))) {
54 REAL_PART(w) = HUGE_VAL;
56 REAL_PART(w) = INFINITY;
58 IMAG_PART(w) = copysign(0.0, cimag(z));