Mercurial > sdl-ios-xcode
annotate src/libm/k_sin.c @ 2847:7d020441fa81
Don't hardcode RECT for fragment program texture targets.
Now we can generate what a given system needs when compiling the shader.
author | Ryan C. Gordon <icculus@icculus.org> |
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date | Sun, 07 Dec 2008 07:06:34 +0000 |
parents | a98604b691c8 |
children | dc1eb82ffdaa |
rev | line source |
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Expanded the libm support and put it into a separate directory.
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1 /* @(#)k_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 char rcsid[] = "$NetBSD: k_sin.c,v 1.8 1995/05/10 20:46:31 jtc Exp $"; |
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15 #endif |
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16 |
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17 /* __kernel_sin( x, y, iy) |
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18 * kernel sin function on [-pi/4, pi/4], pi/4 ~ 0.7854 |
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19 * Input x is assumed to be bounded by ~pi/4 in magnitude. |
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20 * Input y is the tail of x. |
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21 * Input iy indicates whether y is 0. (if iy=0, y assume to be 0). |
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22 * |
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23 * Algorithm |
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24 * 1. Since sin(-x) = -sin(x), we need only to consider positive x. |
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25 * 2. if x < 2^-27 (hx<0x3e400000 0), return x with inexact if x!=0. |
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26 * 3. sin(x) is approximated by a polynomial of degree 13 on |
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27 * [0,pi/4] |
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28 * 3 13 |
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29 * sin(x) ~ x + S1*x + ... + S6*x |
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30 * where |
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31 * |
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32 * |sin(x) 2 4 6 8 10 12 | -58 |
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33 * |----- - (1+S1*x +S2*x +S3*x +S4*x +S5*x +S6*x )| <= 2 |
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34 * | x | |
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35 * |
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36 * 4. sin(x+y) = sin(x) + sin'(x')*y |
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37 * ~ sin(x) + (1-x*x/2)*y |
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38 * For better accuracy, let |
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39 * 3 2 2 2 2 |
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40 * r = x *(S2+x *(S3+x *(S4+x *(S5+x *S6)))) |
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41 * then 3 2 |
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42 * sin(x) = x + (S1*x + (x *(r-y/2)+y)) |
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43 */ |
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44 |
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45 #include "math.h" |
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46 #include "math_private.h" |
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47 |
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48 #ifdef __STDC__ |
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49 static const double |
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50 #else |
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51 static double |
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52 #endif |
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53 half = 5.00000000000000000000e-01, /* 0x3FE00000, 0x00000000 */ |
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54 S1 = -1.66666666666666324348e-01, /* 0xBFC55555, 0x55555549 */ |
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55 S2 = 8.33333333332248946124e-03, /* 0x3F811111, 0x1110F8A6 */ |
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56 S3 = -1.98412698298579493134e-04, /* 0xBF2A01A0, 0x19C161D5 */ |
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57 S4 = 2.75573137070700676789e-06, /* 0x3EC71DE3, 0x57B1FE7D */ |
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58 S5 = -2.50507602534068634195e-08, /* 0xBE5AE5E6, 0x8A2B9CEB */ |
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59 S6 = 1.58969099521155010221e-10; /* 0x3DE5D93A, 0x5ACFD57C */ |
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60 |
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61 #ifdef __STDC__ |
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62 double attribute_hidden |
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63 __kernel_sin(double x, double y, int iy) |
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64 #else |
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65 double attribute_hidden |
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66 __kernel_sin(x, y, iy) |
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67 double x, y; |
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68 int iy; /* iy=0 if y is zero */ |
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69 #endif |
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70 { |
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71 double z, r, v; |
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72 int32_t ix; |
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73 GET_HIGH_WORD(ix, x); |
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74 ix &= 0x7fffffff; /* high word of x */ |
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75 if (ix < 0x3e400000) { /* |x| < 2**-27 */ |
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76 if ((int) x == 0) |
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77 return x; |
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78 } /* generate inexact */ |
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79 z = x * x; |
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80 v = z * x; |
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81 r = S2 + z * (S3 + z * (S4 + z * (S5 + z * S6))); |
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82 if (iy == 0) |
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83 return x + v * (S1 + z * r); |
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84 else |
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85 return x - ((z * (half * y - v * r) - y) - v * S1); |
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86 } |