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annotate packages/language/c/libm/current/src/complex/csqrtf.c @ 3260:77f9d3253c3e

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Add: Complex number header and library (single and double precision floating point), port from Newlib. Add: Single precision floating point library, port from Newlib. [ Bugzilla 1001539 ]
author vae
date Sun, 25 Aug 2013 14:38:57 +0000
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3260
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1 /* $NetBSD: csqrtf.c,v 1.1 2007/08/20 16:01:37 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 #include <complex.h>
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36 #include <math.h>
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37
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38 float complex
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39 csqrtf(float complex z)
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40 {
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41 float complex w;
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42 float x, y, r, t, scale;
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43
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44 x = crealf (z);
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45 y = cimagf (z);
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46
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47 if (y == 0.0f) {
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48 if (x < 0.0f) {
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49 w = 0.0f + sqrtf(-x) * I;
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50 return w;
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51 } else if (x == 0.0f) {
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52 return (0.0f + y * I);
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53 } else {
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54 w = sqrtf(x) + y * I;
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55 return w;
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56 }
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57 }
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58
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59 if (x == 0.0f) {
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60 r = fabsf(y);
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61 r = sqrtf(0.5f * r);
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62 if (y > 0)
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63 w = r + r * I;
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64 else
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65 w = r - r * I;
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66 return w;
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67 }
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68
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69 /* Rescale to avoid internal overflow or underflow. */
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70 if ((fabsf(x) > 4.0f) || (fabsf(y) > 4.0f)) {
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71 x *= 0.25f;
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72 y *= 0.25f;
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73 scale = 2.0f;
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74 } else {
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75 #if 1
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76 x *= 6.7108864e7f; /* 2^26 */
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77 y *= 6.7108864e7f;
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78 scale = 1.220703125e-4f; /* 2^-13 */
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79 #else
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80 x *= 4.0f;
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81 y *= 4.0f;
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82 scale = 0.5f;
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83 #endif
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84 }
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85 w = x + y * I;
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86 r = cabsf(w);
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87 if( x > 0 ) {
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88 t = sqrtf(0.5f * r + 0.5f * x);
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89 r = scale * fabsf((0.5f * y) / t);
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90 t *= scale;
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91 } else {
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92 r = sqrtf(0.5f * r - 0.5f * x);
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93 t = scale * fabsf((0.5f * y) / r);
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94 r *= scale;
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95 }
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96
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97 if (y < 0)
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98 w = t - r * I;
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99 else
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100 w = t + r * I;
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101 return w;
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102 }