1 /* 2 * Copyright (c) 1987 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #ifndef lint 9 static char sccsid[] = "@(#)sincos.c 5.5 (Berkeley) 10/09/90"; 10 #endif /* not lint */ 11 12 #include "trig.h" 13 double 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 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