1 /* 2 * Copyright (c) 1987 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * All recipients should regard themselves as participants in an ongoing 8 * research project and hence should feel obligated to report their 9 * experiences (good or bad) with these elementary function codes, using 10 * the sendbug(8) program, to the authors. 11 */ 12 13 #ifndef lint 14 static char sccsid[] = "@(#)sincos.c 5.4 (Berkeley) 06/01/90"; 15 #endif /* not lint */ 16 17 #include "trig.h" 18 double 19 sin(x) 20 double x; 21 { 22 double a,c,z; 23 24 if(!finite(x)) /* sin(NaN) and sin(INF) must be NaN */ 25 return x-x; 26 x=drem(x,PI2); /* reduce x into [-PI,PI] */ 27 a=copysign(x,one); 28 if (a >= PIo4) { 29 if(a >= PI3o4) /* ... in [3PI/4,PI] */ 30 x = copysign((a = PI-a),x); 31 else { /* ... in [PI/4,3PI/4] */ 32 a = PIo2-a; /* rtn. sign(x)*C(PI/2-|x|) */ 33 z = a*a; 34 c = cos__C(z); 35 z *= half; 36 a = (z >= thresh ? half-((z-half)-c) : one-(z-c)); 37 return copysign(a,x); 38 } 39 } 40 41 if (a < small) { /* rtn. S(x) */ 42 big+a; 43 return x; 44 } 45 return x+x*sin__S(x*x); 46 } 47 48 double 49 cos(x) 50 double x; 51 { 52 double a,c,z,s = 1.0; 53 54 if(!finite(x)) /* cos(NaN) and cos(INF) must be NaN */ 55 return x-x; 56 x=drem(x,PI2); /* reduce x into [-PI,PI] */ 57 a=copysign(x,one); 58 if (a >= PIo4) { 59 if (a >= PI3o4) { /* ... in [3PI/4,PI] */ 60 a = PI-a; 61 s = negone; 62 } 63 else { /* ... in [PI/4,3PI/4] */ 64 a = PIo2-a; 65 return a+a*sin__S(a*a); /* rtn. S(PI/2-|x|) */ 66 } 67 } 68 if (a < small) { 69 big+a; 70 return s; /* rtn. s*C(a) */ 71 } 72 z = a*a; 73 c = cos__C(z); 74 z *= half; 75 a = (z >= thresh ? half-((z-half)-c) : one-(z-c)); 76 return copysign(a,s); 77 } 78