diff options
Diffstat (limited to 'src/MSL_C.PPCEABI.bare.H/s_cos.c')
-rw-r--r-- | src/MSL_C.PPCEABI.bare.H/s_cos.c | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/src/MSL_C.PPCEABI.bare.H/s_cos.c b/src/MSL_C.PPCEABI.bare.H/s_cos.c new file mode 100644 index 0000000..833d871 --- /dev/null +++ b/src/MSL_C.PPCEABI.bare.H/s_cos.c @@ -0,0 +1,75 @@ +/* @(#)s_cos.c 1.3 95/01/18 */ +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunSoft, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ +/* cos(x) + * Return cosine function of x. + * + * kernel function: + * __kernel_sin ... sine function on [-pi/4,pi/4] + * __kernel_cos ... cosine 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 "fdlibm.h" +#ifdef __STDC__ +double cos(double x) +#else +double cos(x) +double x; +#endif +{ + double y[2], z = 0.0; + int n, ix; + /* High word of x. */ + ix = __HI(x); + /* |x| ~< pi/4 */ + ix &= 0x7fffffff; + if (ix <= 0x3fe921fb) + return __kernel_cos(x, z); + /* cos(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_cos(y[0], y[1]); + case 1: + return -__kernel_sin(y[0], y[1], 1); + case 2: + return -__kernel_cos(y[0], y[1]); + default: + return __kernel_sin(y[0], y[1], 1); + } + } +} |