1 /* origin: FreeBSD /usr/src/lib/msun/src/k_cosf.c */ 2 /* 3 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 4 * Debugged and optimized by Bruce D. Evans. 5 */ 6 /* 7 * ==================================================== 8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 9 * 10 * Developed at SunPro, a Sun Microsystems, Inc. business. 11 * Permission to use, copy, modify, and distribute this 12 * software is freely granted, provided that this notice 13 * is preserved. 14 * ==================================================== 15 */ 16 17 #include "libm.h" 18 19 /* |cos(x) - c(x)| < 2**-34.1 (~[-5.37e-11, 5.295e-11]). */ 20 static const double 21 C0 = -0x1ffffffd0c5e81.0p-54, /* -0.499999997251031003120 */ 22 C1 = 0x155553e1053a42.0p-57, /* 0.0416666233237390631894 */ 23 C2 = -0x16c087e80f1e27.0p-62, /* -0.00138867637746099294692 */ 24 C3 = 0x199342e0ee5069.0p-68; /* 0.0000243904487962774090654 */ 25 26 float __cosdf(double x) 27 { 28 double_t r, w, z; 29 30 /* Try to optimize for parallel evaluation as in __tandf.c. */ 31 z = x*x; 32 w = z*z; 33 r = C2+z*C3; 34 return ((1.0+z*C0) + w*C1) + (w*z)*r; 35 } 36