1 | /* s_sinl.c -- long double version of s_sin.c. |
2 | */ |
3 | |
4 | /* |
5 | * ==================================================== |
6 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
7 | * |
8 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
9 | * Permission to use, copy, modify, and distribute this |
10 | * software is freely granted, provided that this notice |
11 | * is preserved. |
12 | * ==================================================== |
13 | */ |
14 | |
15 | #if defined(LIBM_SCCS) && !defined(lint) |
16 | static char rcsid[] = "$NetBSD: $" ; |
17 | #endif |
18 | |
19 | /* sinl(x) |
20 | * Return sine function of x. |
21 | * |
22 | * kernel function: |
23 | * __kernel_sinl ... sine function on [-pi/4,pi/4] |
24 | * __kernel_cosl ... cose function on [-pi/4,pi/4] |
25 | * __ieee754_rem_pio2l ... argument reduction routine |
26 | * |
27 | * Method. |
28 | * Let S,C and T denote the sin, cos and tan respectively on |
29 | * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2 |
30 | * in [-pi/4 , +pi/4], and let n = k mod 4. |
31 | * We have |
32 | * |
33 | * n sin(x) cos(x) tan(x) |
34 | * ---------------------------------------------------------- |
35 | * 0 S C T |
36 | * 1 C -S -1/T |
37 | * 2 -S -C T |
38 | * 3 -C S -1/T |
39 | * ---------------------------------------------------------- |
40 | * |
41 | * Special cases: |
42 | * Let trig be any of sin, cos, or tan. |
43 | * trig(+-INF) is NaN, with signals; |
44 | * trig(NaN) is that NaN; |
45 | * |
46 | * Accuracy: |
47 | * TRIG(x) returns trig(x) nearly rounded |
48 | */ |
49 | |
50 | #include <errno.h> |
51 | #include <math.h> |
52 | #include <math_private.h> |
53 | #include <libm-alias-ldouble.h> |
54 | |
55 | long double __sinl(long double x) |
56 | { |
57 | long double y[2],z=0.0; |
58 | int32_t n, se, i0, i1; |
59 | |
60 | /* High word of x. */ |
61 | GET_LDOUBLE_WORDS(se,i0,i1,x); |
62 | |
63 | /* |x| ~< pi/4 */ |
64 | se &= 0x7fff; |
65 | if(se < 0x3ffe || (se == 0x3ffe && i0 <= 0xc90fdaa2)) |
66 | return __kernel_sinl(x,z,0); |
67 | |
68 | /* sin(Inf or NaN) is NaN */ |
69 | else if (se==0x7fff) { |
70 | if (i1 == 0 && i0 == 0x80000000) |
71 | __set_errno (EDOM); |
72 | return x-x; |
73 | } |
74 | |
75 | /* argument reduction needed */ |
76 | else { |
77 | n = __ieee754_rem_pio2l(x,y); |
78 | switch(n&3) { |
79 | case 0: return __kernel_sinl(y[0],y[1],1); |
80 | case 1: return __kernel_cosl(y[0],y[1]); |
81 | case 2: return -__kernel_sinl(y[0],y[1],1); |
82 | default: |
83 | return -__kernel_cosl(y[0],y[1]); |
84 | } |
85 | } |
86 | } |
87 | libm_alias_ldouble (__sin, sin) |
88 | |