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annotate src/libm/s_sin.c @ 4833:34fb492cefe3

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Shaped windows for Cocoa build and testshape runs, but the actual shaping doesn't work. Something, however, is definitely happening, because we get the backgrounds drawn in two different colors.
author egottlieb
date Thu, 05 Aug 2010 01:03:24 -0400
parents dc1eb82ffdaa
children
rev   line source
2756
a98604b691c8 Expanded the libm support and put it into a separate directory.
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1 /* @(#)s_sin.c 5.1 93/09/24 */
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2 /*
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3 * ====================================================
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4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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5 *
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6 * Developed at SunPro, a Sun Microsystems, Inc. business.
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7 * Permission to use, copy, modify, and distribute this
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8 * software is freely granted, provided that this notice
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9 * is preserved.
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10 * ====================================================
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11 */
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12
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13 #if defined(LIBM_SCCS) && !defined(lint)
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14 static const char rcsid[] =
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15 "$NetBSD: s_sin.c,v 1.7 1995/05/10 20:48:15 jtc Exp $";
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16 #endif
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17
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18 /* sin(x)
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19 * Return sine function of x.
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20 *
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21 * kernel function:
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22 * __kernel_sin ... sine function on [-pi/4,pi/4]
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23 * __kernel_cos ... cose function on [-pi/4,pi/4]
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24 * __ieee754_rem_pio2 ... argument reduction routine
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25 *
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26 * Method.
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27 * Let S,C and T denote the sin, cos and tan respectively on
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28 * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
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29 * in [-pi/4 , +pi/4], and let n = k mod 4.
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30 * We have
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31 *
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32 * n sin(x) cos(x) tan(x)
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33 * ----------------------------------------------------------
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34 * 0 S C T
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35 * 1 C -S -1/T
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36 * 2 -S -C T
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37 * 3 -C S -1/T
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38 * ----------------------------------------------------------
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39 *
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40 * Special cases:
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41 * Let trig be any of sin, cos, or tan.
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42 * trig(+-INF) is NaN, with signals;
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43 * trig(NaN) is that NaN;
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44 *
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45 * Accuracy:
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46 * TRIG(x) returns trig(x) nearly rounded
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47 */
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48
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49 #include "math.h"
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50 #include "math_private.h"
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51
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52 libm_hidden_proto(sin)
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53 #ifdef __STDC__
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54 double sin(double x)
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55 #else
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56 double sin(x)
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57 double x;
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58 #endif
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59 {
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60 double y[2], z = 0.0;
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61 int32_t n, ix;
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62
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63 /* High word of x. */
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64 GET_HIGH_WORD(ix, x);
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65
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66 /* |x| ~< pi/4 */
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67 ix &= 0x7fffffff;
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68 if (ix <= 0x3fe921fb)
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69 return __kernel_sin(x, z, 0);
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70
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71 /* sin(Inf or NaN) is NaN */
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72 else if (ix >= 0x7ff00000)
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73 return x - x;
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74
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75 /* argument reduction needed */
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76 else {
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77 n = __ieee754_rem_pio2(x, y);
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78 switch (n & 3) {
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79 case 0:
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80 return __kernel_sin(y[0], y[1], 1);
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81 case 1:
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82 return __kernel_cos(y[0], y[1]);
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83 case 2:
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84 return -__kernel_sin(y[0], y[1], 1);
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85 default:
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86 return -__kernel_cos(y[0], y[1]);
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87 }
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88 }
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89 }
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90
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91 libm_hidden_def(sin)