[444] | 1 | /* $NetBSD: catan.c,v 1.1 2007/08/20 16:01:32 drochner Exp $ */ |
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| 2 | |
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| 3 | /*- |
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| 4 | * Copyright (c) 2007 The NetBSD Foundation, Inc. |
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| 5 | * All rights reserved. |
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| 6 | * |
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| 7 | * This code is derived from software written by Stephen L. Moshier. |
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| 8 | * It is redistributed by the NetBSD Foundation by permission of the author. |
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| 9 | * |
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| 10 | * Redistribution and use in source and binary forms, with or without |
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| 11 | * modification, are permitted provided that the following conditions |
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| 12 | * are met: |
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| 13 | * 1. Redistributions of source code must retain the above copyright |
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| 14 | * notice, this list of conditions and the following disclaimer. |
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| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
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| 16 | * notice, this list of conditions and the following disclaimer in the |
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| 17 | * documentation and/or other materials provided with the distribution. |
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| 18 | * |
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| 19 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
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| 20 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
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| 21 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
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| 22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
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| 23 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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| 24 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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| 25 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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| 26 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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| 27 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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| 28 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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| 29 | * POSSIBILITY OF SUCH DAMAGE. |
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| 30 | * |
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| 31 | * imported and modified include for newlib 2010/10/03 |
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| 32 | * Marco Atzeri <marco_atzeri@yahoo.it> |
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| 33 | */ |
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| 34 | |
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| 35 | /* |
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| 36 | FUNCTION |
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| 37 | <<catan>>, <<catanf>>---complex arc tangent |
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| 38 | |
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| 39 | INDEX |
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| 40 | catan |
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| 41 | INDEX |
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| 42 | catanf |
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| 43 | |
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| 44 | SYNOPSIS |
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| 45 | #include <complex.h> |
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| 46 | double complex catan(double complex <[z]>); |
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| 47 | float complex catanf(float complex <[z]>); |
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| 48 | |
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| 49 | |
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| 50 | DESCRIPTION |
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| 51 | @ifnottex |
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| 52 | These functions compute the complex arc tangent of <[z]>, |
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| 53 | with branch cuts outside the interval [-i, +i] along the |
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| 54 | imaginary axis. |
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| 55 | @end ifnottex |
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| 56 | @tex |
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| 57 | These functions compute the complex arc tangent of <[z]>, |
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| 58 | with branch cuts outside the interval [$-i$, $+i$] along the |
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| 59 | imaginary axis. |
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| 60 | @end tex |
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| 61 | |
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| 62 | <<catanf>> is identical to <<catan>>, except that it performs |
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| 63 | its calculations on <<floats complex>>. |
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| 64 | |
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| 65 | RETURNS |
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| 66 | @ifnottex |
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| 67 | These functions return the complex arc tangent value, in the range |
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| 68 | of a strip mathematically unbounded along the imaginary axis |
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| 69 | and in the interval [-pi/2, +pi/2] along the real axis. |
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| 70 | @end ifnottex |
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| 71 | @tex |
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| 72 | These functions return the complex arc tangent, in the range |
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| 73 | of a strip mathematically unbounded along the imaginary axis |
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| 74 | and in the interval [$-\pi/2$, $+\pi/2$] along the real axis. |
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| 75 | @end tex |
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| 76 | |
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| 77 | PORTABILITY |
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| 78 | <<catan>> and <<catanf>> are ISO C99 |
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| 79 | |
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| 80 | QUICKREF |
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| 81 | <<catan>> and <<catanf>> are ISO C99 |
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| 82 | |
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| 83 | */ |
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| 84 | |
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| 85 | |
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| 86 | #include <complex.h> |
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| 87 | #include <math.h> |
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| 88 | #include "cephes_subr.h" |
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| 89 | |
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| 90 | #ifdef __weak_alias |
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| 91 | __weak_alias(catan, _catan) |
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| 92 | #endif |
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| 93 | |
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| 94 | double complex |
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| 95 | catan(double complex z) |
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| 96 | { |
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| 97 | double complex w; |
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| 98 | double a, t, x, x2, y; |
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| 99 | |
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| 100 | x = creal(z); |
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| 101 | y = cimag(z); |
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| 102 | |
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| 103 | if ((x == 0.0) && (y > 1.0)) |
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| 104 | goto ovrf; |
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| 105 | |
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| 106 | x2 = x * x; |
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| 107 | a = 1.0 - x2 - (y * y); |
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| 108 | if (a == 0.0) |
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| 109 | goto ovrf; |
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| 110 | |
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| 111 | t = 0.5 * atan2(2.0 * x, a); |
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| 112 | w = _redupi(t); |
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| 113 | |
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| 114 | t = y - 1.0; |
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| 115 | a = x2 + (t * t); |
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| 116 | if (a == 0.0) |
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| 117 | goto ovrf; |
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| 118 | |
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| 119 | t = y + 1.0; |
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| 120 | a = (x2 + (t * t))/a; |
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| 121 | w = w + (0.25 * log(a)) * I; |
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| 122 | return w; |
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| 123 | |
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| 124 | ovrf: |
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| 125 | #if 0 |
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| 126 | mtherr ("catan", OVERFLOW); |
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| 127 | #endif |
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| 128 | w = HUGE_VAL + HUGE_VAL * I; |
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| 129 | return w; |
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| 130 | } |
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