summaryrefslogtreecommitdiff log msg author committer range
path: root/src/math/s_sin.c
diff options
 context: 12345678910152025303540 space: includeignore mode: unifiedssdiffstat only
Diffstat (limited to 'src/math/s_sin.c')
-rw-r--r--src/math/s_sin.c74
1 files changed, 74 insertions, 0 deletions
 diff --git a/src/math/s_sin.c b/src/math/s_sin.cnew file mode 100644index 00000000..2a2774ed--- /dev/null+++ b/src/math/s_sin.c@@ -0,0 +1,74 @@+/* @(#)s_sin.c 5.1 93/09/24 */+/*+ * ====================================================+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.+ *+ * Developed at SunPro, a Sun Microsystems, Inc. business.+ * Permission to use, copy, modify, and distribute this+ * software is freely granted, provided that this notice+ * is preserved.+ * ====================================================+ */++/* sin(x)+ * Return sine function of x.+ *+ * kernel function:+ * __kernel_sin ... sine function on [-pi/4,pi/4]+ * __kernel_cos ... cose function on [-pi/4,pi/4]+ * __ieee754_rem_pio2 ... argument reduction routine+ *+ * Method.+ * Let S,C and T denote the sin, cos and tan respectively on+ * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2+ * in [-pi/4 , +pi/4], and let n = k mod 4.+ * We have+ *+ * n sin(x) cos(x) tan(x)+ * ----------------------------------------------------------+ * 0 S C T+ * 1 C -S -1/T+ * 2 -S -C T+ * 3 -C S -1/T+ * ----------------------------------------------------------+ *+ * Special cases:+ * Let trig be any of sin, cos, or tan.+ * trig(+-INF) is NaN, with signals;+ * trig(NaN) is that NaN;+ *+ * Accuracy:+ * TRIG(x) returns trig(x) nearly rounded+ */++#include +#include "math_private.h"++double+sin(double x)+{+ double y[2],z=0.0;+ int32_t n, ix;++ /* High word of x. */+ GET_HIGH_WORD(ix,x);++ /* |x| ~< pi/4 */+ ix &= 0x7fffffff;+ if(ix <= 0x3fe921fb) return __kernel_sin(x,z,0);++ /* sin(Inf or NaN) is NaN */+ else if (ix>=0x7ff00000) return x-x;++ /* argument reduction needed */+ else {+ n = __ieee754_rem_pio2(x,y);+ switch(n&3) {+ case 0: return __kernel_sin(y[0],y[1],1);+ case 1: return __kernel_cos(y[0],y[1]);+ case 2: return -__kernel_sin(y[0],y[1],1);+ default:+ return -__kernel_cos(y[0],y[1]);+ }+ }+}