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1 /* origin: FreeBSD /usr/src/lib/msun/src/k_cos.c */ | 1 /* origin: FreeBSD /usr/src/lib/msun/src/k_cos.c */ |
2 /* | 2 /* |
3 * ==================================================== | 3 * ==================================================== |
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. | 4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
5 * | 5 * |
6 * Developed at SunSoft, a Sun Microsystems, Inc. business. | 6 * Developed at SunSoft, a Sun Microsystems, Inc. business. |
7 * Permission to use, copy, modify, and distribute this | 7 * Permission to use, copy, modify, and distribute this |
8 * software is freely granted, provided that this notice | 8 * software is freely granted, provided that this notice |
9 * is preserved. | 9 * is preserved. |
10 * ==================================================== | 10 * ==================================================== |
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43 * and tmp having the same precision as x. If they have extra | 43 * and tmp having the same precision as x. If they have extra |
44 * precision due to compiler bugs, then the extra precision is | 44 * precision due to compiler bugs, then the extra precision is |
45 * only good provided it is retained in all terms of the final | 45 * only good provided it is retained in all terms of the final |
46 * expression for cos(). Retention happens in all cases tested | 46 * expression for cos(). Retention happens in all cases tested |
47 * under FreeBSD, so don't pessimize things by forcibly clipping | 47 * under FreeBSD, so don't pessimize things by forcibly clipping |
48 * any extra precision in w. | 48 * any extra precision in w. |
49 */ | 49 */ |
50 | 50 |
51 #include "libm.h" | 51 #include "libm.h" |
52 | 52 |
53 static const double | 53 static const double C1 = |
54 C1 = 4.16666666666666019037e-02, /* 0x3FA55555, 0x5555554C */ | 54 4.16666666666666019037e-02, /* 0x3FA55555, 0x5555554C */ |
55 C2 = -1.38888888888741095749e-03, /* 0xBF56C16C, 0x16C15177 */ | 55 C2 = -1.38888888888741095749e-03, /* 0xBF56C16C, 0x16C15177 */ |
56 C3 = 2.48015872894767294178e-05, /* 0x3EFA01A0, 0x19CB1590 */ | 56 C3 = 2.48015872894767294178e-05, /* 0x3EFA01A0, 0x19CB1590 */ |
57 C4 = -2.75573143513906633035e-07, /* 0xBE927E4F, 0x809C52AD */ | 57 C4 = -2.75573143513906633035e-07, /* 0xBE927E4F, 0x809C52AD */ |
58 C5 = 2.08757232129817482790e-09, /* 0x3E21EE9E, 0xBDB4B1C4 */ | 58 C5 = 2.08757232129817482790e-09, /* 0x3E21EE9E, 0xBDB4B1C4 */ |
59 C6 = -1.13596475577881948265e-11; /* 0xBDA8FAE9, 0xBE8838D4 */ | 59 C6 = -1.13596475577881948265e-11; /* 0xBDA8FAE9, 0xBE8838D4 */ |
60 | 60 |
61 double __cos(double x, double y) | 61 double __cos(double x, double y) { |
62 { | 62 double_t hz, z, r, w; |
63 » double_t hz,z,r,w; | |
64 | 63 |
65 » z = x*x; | 64 z = x * x; |
66 » w = z*z; | 65 w = z * z; |
67 » r = z*(C1+z*(C2+z*C3)) + w*w*(C4+z*(C5+z*C6)); | 66 r = z * (C1 + z * (C2 + z * C3)) + w * w * (C4 + z * (C5 + z * C6)); |
68 » hz = 0.5*z; | 67 hz = 0.5 * z; |
69 » w = 1.0-hz; | 68 w = 1.0 - hz; |
70 » return w + (((1.0-w)-hz) + (z*r-x*y)); | 69 return w + (((1.0 - w) - hz) + (z * r - x * y)); |
71 } | 70 } |
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