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author | pommicket <pommicket@gmail.com> | 2022-02-20 13:18:21 -0800 |
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committer | pommicket <pommicket@gmail.com> | 2022-02-20 13:18:21 -0800 |
commit | 9bc8a11afeed3569736b89754012e3ca22ee10f6 (patch) | |
tree | 5f0ec0d5c05f879b1ee86adfa654ed3ef2178d5f /05/musl-0.6.0/src/math/s_sin.c | |
parent | 0f97a589b800bdb71dda05984192f0f66a52edaa (diff) |
conclusion
Diffstat (limited to '05/musl-0.6.0/src/math/s_sin.c')
-rw-r--r-- | 05/musl-0.6.0/src/math/s_sin.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/05/musl-0.6.0/src/math/s_sin.c b/05/musl-0.6.0/src/math/s_sin.c new file mode 100644 index 0000000..2a2774e --- /dev/null +++ b/05/musl-0.6.0/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 <math.h> +#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]); + } + } +} |