/src/moddable/xs/tools/fdlibm/s_sin.c
Line | Count | Source |
1 | | /* |
2 | | * ==================================================== |
3 | | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
4 | | * |
5 | | * Developed at SunPro, a Sun Microsystems, Inc. business. |
6 | | * Permission to use, copy, modify, and distribute this |
7 | | * software is freely granted, provided that this notice |
8 | | * is preserved. |
9 | | * ==================================================== |
10 | | */ |
11 | | |
12 | | /* sin(x) |
13 | | * Return sine function of x. |
14 | | * |
15 | | * kernel function: |
16 | | * __kernel_sin ... sine function on [-pi/4,pi/4] |
17 | | * __kernel_cos ... cose function on [-pi/4,pi/4] |
18 | | * __ieee754_rem_pio2 ... argument reduction routine |
19 | | * |
20 | | * Method. |
21 | | * Let S,C and T denote the sin, cos and tan respectively on |
22 | | * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2 |
23 | | * in [-pi/4 , +pi/4], and let n = k mod 4. |
24 | | * We have |
25 | | * |
26 | | * n sin(x) cos(x) tan(x) |
27 | | * ---------------------------------------------------------- |
28 | | * 0 S C T |
29 | | * 1 C -S -1/T |
30 | | * 2 -S -C T |
31 | | * 3 -C S -1/T |
32 | | * ---------------------------------------------------------- |
33 | | * |
34 | | * Special cases: |
35 | | * Let trig be any of sin, cos, or tan. |
36 | | * trig(+-INF) is NaN, with signals; |
37 | | * trig(NaN) is that NaN; |
38 | | * |
39 | | * Accuracy: |
40 | | * TRIG(x) returns trig(x) nearly rounded |
41 | | */ |
42 | | |
43 | | #define INLINE_REM_PIO2 |
44 | | #include "math_private.h" |
45 | | #include "e_rem_pio2.c" |
46 | | |
47 | | double |
48 | | s_sin(double x) |
49 | 17.8k | { |
50 | 17.8k | double y[2],z=0.0; |
51 | 17.8k | int32_t n, ix; |
52 | | |
53 | | /* High word of x. */ |
54 | 17.8k | GET_HIGH_WORD(ix,x); |
55 | | |
56 | | /* |x| ~< pi/4 */ |
57 | 17.8k | ix &= 0x7fffffff; |
58 | 17.8k | if(ix <= 0x3fe921fb) { |
59 | 2.32k | if(ix<0x3e500000) /* |x| < 2**-26 */ |
60 | 812 | {if((int)x==0) return x;} /* generate inexact */ |
61 | 1.51k | return __kernel_sin(x,z,0); |
62 | 2.32k | } |
63 | | |
64 | | /* sin(Inf or NaN) is NaN */ |
65 | 15.5k | else if (ix>=0x7ff00000) return x-x; |
66 | | |
67 | | /* argument reduction needed */ |
68 | 14.2k | else { |
69 | 14.2k | n = __ieee754_rem_pio2(x,y); |
70 | 14.2k | switch(n&3) { |
71 | 1.50k | case 0: return __kernel_sin(y[0],y[1],1); |
72 | 3.90k | case 1: return __kernel_cos(y[0],y[1]); |
73 | 3.16k | case 2: return -__kernel_sin(y[0],y[1],1); |
74 | 5.69k | default: |
75 | 5.69k | return -__kernel_cos(y[0],y[1]); |
76 | 14.2k | } |
77 | 14.2k | } |
78 | 17.8k | } |