1 /*
2 * Copyright (c) 1987, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * %sccs.include.redist.c%
6 */
7
8 #ifndef lint
9 static char sccsid[] = "@(#)sincos.c 8.1 (Berkeley) 06/04/93";
10 #endif /* not lint */
11
12 #include "trig.h"
13 double
sin(x)14 sin(x)
15 double x;
16 {
17 double a,c,z;
18
19 if(!finite(x)) /* sin(NaN) and sin(INF) must be NaN */
20 return x-x;
21 x=drem(x,PI2); /* reduce x into [-PI,PI] */
22 a=copysign(x,one);
23 if (a >= PIo4) {
24 if(a >= PI3o4) /* ... in [3PI/4,PI] */
25 x = copysign((a = PI-a),x);
26 else { /* ... in [PI/4,3PI/4] */
27 a = PIo2-a; /* rtn. sign(x)*C(PI/2-|x|) */
28 z = a*a;
29 c = cos__C(z);
30 z *= half;
31 a = (z >= thresh ? half-((z-half)-c) : one-(z-c));
32 return copysign(a,x);
33 }
34 }
35
36 if (a < small) { /* rtn. S(x) */
37 big+a;
38 return x;
39 }
40 return x+x*sin__S(x*x);
41 }
42
43 double
cos(x)44 cos(x)
45 double x;
46 {
47 double a,c,z,s = 1.0;
48
49 if(!finite(x)) /* cos(NaN) and cos(INF) must be NaN */
50 return x-x;
51 x=drem(x,PI2); /* reduce x into [-PI,PI] */
52 a=copysign(x,one);
53 if (a >= PIo4) {
54 if (a >= PI3o4) { /* ... in [3PI/4,PI] */
55 a = PI-a;
56 s = negone;
57 }
58 else { /* ... in [PI/4,3PI/4] */
59 a = PIo2-a;
60 return a+a*sin__S(a*a); /* rtn. S(PI/2-|x|) */
61 }
62 }
63 if (a < small) {
64 big+a;
65 return s; /* rtn. s*C(a) */
66 }
67 z = a*a;
68 c = cos__C(z);
69 z *= half;
70 a = (z >= thresh ? half-((z-half)-c) : one-(z-c));
71 return copysign(a,s);
72 }
73