| 1 | /* $NetBSD: cprojl.c,v 1.7 2014/10/10 00:48:18 christos Exp $ */ |
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| 2 | |
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| 3 | /*- |
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| 4 | * Copyright (c) 2010 The NetBSD Foundation, Inc. |
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| 5 | * All rights reserved. |
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| 6 | * |
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| 7 | * Redistribution and use in source and binary forms, with or without |
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| 8 | * modification, are permitted provided that the following conditions |
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| 9 | * are met: |
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| 10 | * 1. Redistributions of source code must retain the above copyright |
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| 11 | * notice, this list of conditions and the following disclaimer. |
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| 12 | * 2. Redistributions in binary form must reproduce the above copyright |
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| 13 | * notice, this list of conditions and the following disclaimer in the |
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| 14 | * documentation and/or other materials provided with the distribution. |
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| 15 | * |
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| 16 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
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| 17 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
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| 18 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
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| 19 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
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| 20 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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| 21 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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| 22 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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| 23 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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| 24 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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| 25 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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| 26 | * POSSIBILITY OF SUCH DAMAGE. |
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| 27 | */ |
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| 28 | #include <sys/cdefs.h> |
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| 29 | __RCSID("$NetBSD: cprojl.c,v 1.7 2014/10/10 00:48:18 christos Exp $"); |
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| 30 | |
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| 31 | #include <complex.h> |
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| 32 | #include <math.h> |
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| 33 | |
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| 34 | #include "../common/fdlibm.h" |
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| 35 | |
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| 36 | /* |
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| 37 | * cprojl(long double complex z) |
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| 38 | * |
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| 39 | * These functions return the value of the projection (not stereographic!) |
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| 40 | * onto the Riemann sphere. |
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| 41 | * |
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| 42 | * z projects to z, except that all complex infinities (even those with one |
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| 43 | * infinite part and one NaN part) project to positive infinity on the real axis. |
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| 44 | * If z has an infinite part, then cproj(z) shall be equivalent to: |
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| 45 | * |
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| 46 | * INFINITY + I * copysign(0.0, cimag(z)) |
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| 47 | */ |
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| 48 | long double complex |
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| 49 | cprojl(long double complex z) |
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| 50 | { |
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| 51 | long_double_complex w = { .z = z }; |
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| 52 | |
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| 53 | /*CONSTCOND*/ |
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| 54 | if (isinf(creall(z)) || isinf(cimagl(z))) { |
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| 55 | #ifdef __INFINITY |
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| 56 | REAL_PART(w) = HUGE_VAL; |
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| 57 | #else |
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| 58 | REAL_PART(w) = INFINITY; |
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| 59 | #endif |
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| 60 | IMAG_PART(w) = copysignl(0.0L, cimagl(z)); |
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| 61 | } |
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| 62 | |
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| 63 | return (w.z); |
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| 64 | } |
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