zenilib  0.5.3.0
s_sin.c
Go to the documentation of this file.
1 /* @(#)s_sin.c 5.1 93/09/24 */
2 /*
3  * ====================================================
5  *
6  * Developed at SunPro, a Sun Microsystems, Inc. business.
7  * Permission to use, copy, modify, and distribute this
8  * software is freely granted, provided that this notice
9  * is preserved.
10  * ====================================================
11  */
12
13 #if defined(LIBM_SCCS) && !defined(lint)
14 static const char rcsid[] =
15  "\$NetBSD: s_sin.c,v 1.7 1995/05/10 20:48:15 jtc Exp \$";
16 #endif
17
18 /* sin(x)
19  * Return sine function of x.
20  *
21  * kernel function:
22  * __kernel_sin ... sine function on [-pi/4,pi/4]
23  * __kernel_cos ... cose function on [-pi/4,pi/4]
24  * __ieee754_rem_pio2 ... argument reduction routine
25  *
26  * Method.
27  * Let S,C and T denote the sin, cos and tan respectively on
28  * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
29  * in [-pi/4 , +pi/4], and let n = k mod 4.
30  * We have
31  *
32  * n sin(x) cos(x) tan(x)
33  * ----------------------------------------------------------
34  * 0 S C T
35  * 1 C -S -1/T
36  * 2 -S -C T
37  * 3 -C S -1/T
38  * ----------------------------------------------------------
39  *
40  * Special cases:
41  * Let trig be any of sin, cos, or tan.
42  * trig(+-INF) is NaN, with signals;
43  * trig(NaN) is that NaN;
44  *
45  * Accuracy:
46  * TRIG(x) returns trig(x) nearly rounded
47  */
48
49 #include "math_libm.h"
50 #include "math_private.h"
51
53 #ifdef __STDC__
54  double sin(double x)
55 #else
56  double sin(x)
57  double x;
58 #endif
59 {
60  double y[2], z = 0.0;
61  int32_t n, ix;
62
63  /* High word of x. */
64  GET_HIGH_WORD(ix, x);
65
66  /* |x| ~< pi/4 */
67  ix &= 0x7fffffff;
68  if (ix <= 0x3fe921fb)
69  return __kernel_sin(x, z, 0);
70
71  /* sin(Inf or NaN) is NaN */
72  else if (ix >= 0x7ff00000)
73  return x - x;
74
75  /* argument reduction needed */
76  else {
77  n = __ieee754_rem_pio2(x, y);
78  switch (n & 3) {
79  case 0:
80  return __kernel_sin(y[0], y[1], 1);
81  case 1:
82  return __kernel_cos(y[0], y[1]);
83  case 2:
84  return -__kernel_sin(y[0], y[1], 1);
85  default:
86  return -__kernel_cos(y[0], y[1]);
87  }
88  }
89 }
90
#define GET_HIGH_WORD(i, d)
Definition: math_private.h:102
GLclampd n
Definition: glew.h:7287
EGLSurface EGLint x
Definition: eglext.h:293
long int32_t
Definition: types.h:9
#define libm_hidden_def(x)
Definition: math_private.h:26
double __kernel_cos(double, double) attribute_hidden
double sin(double x)
Definition: s_sin.c:56
EGLSurface EGLint EGLint y
Definition: eglext.h:293
int32_t ix
Definition: e_rem_pio2.c:100
#define libm_hidden_proto(x)
Definition: math_private.h:25
GLint GLint GLint GLint z
Definition: gl2ext.h:1214
double __kernel_sin(double, double, int) attribute_hidden
int __ieee754_rem_pio2(double, double *) attribute_hidden