| /* From: @(#)k_cos.c 1.3 95/01/18 */ |
| /* |
| * ==================================================== |
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| * Copyright (c) 2008 Steven G. Kargl, David Schultz, Bruce D. Evans. |
| * |
| * 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. |
| * ==================================================== |
| */ |
| |
| #include <sys/cdefs.h> |
| __FBSDID("$FreeBSD$"); |
| |
| /* |
| * ld128 version of k_cos.c. See ../src/k_cos.c for most comments. |
| */ |
| |
| #include "math_private.h" |
| |
| /* |
| * Domain [-0.7854, 0.7854], range ~[-1.17e-39, 1.19e-39]: |
| * |cos(x) - c(x))| < 2**-129.3 |
| * |
| * 113-bit precision requires more care than 64-bit precision, since |
| * simple methods give a minimax polynomial with coefficient for x^2 |
| * that is 1 ulp below 0.5, but we want it to be precisely 0.5. See |
| * ../ld80/k_cosl.c for more details. |
| */ |
| static const double |
| one = 1.0; |
| static const long double |
| C1 = 4.16666666666666666666666666666666667e-02L, |
| C2 = -1.38888888888888888888888888888888834e-03L, |
| C3 = 2.48015873015873015873015873015446795e-05L, |
| C4 = -2.75573192239858906525573190949988493e-07L, |
| C5 = 2.08767569878680989792098886701451072e-09L, |
| C6 = -1.14707455977297247136657111139971865e-11L, |
| C7 = 4.77947733238738518870113294139830239e-14L, |
| C8 = -1.56192069685858079920640872925306403e-16L, |
| C9 = 4.11031762320473354032038893429515732e-19L, |
| C10= -8.89679121027589608738005163931958096e-22L, |
| C11= 1.61171797801314301767074036661901531e-24L, |
| C12= -2.46748624357670948912574279501044295e-27L; |
| |
| long double |
| __kernel_cosl(long double x, long double y) |
| { |
| long double hz,z,r,w; |
| |
| z = x*x; |
| r = z*(C1+z*(C2+z*(C3+z*(C4+z*(C5+z*(C6+z*(C7+ |
| z*(C8+z*(C9+z*(C10+z*(C11+z*C12))))))))))); |
| hz = 0.5*z; |
| w = one-hz; |
| return w + (((one-w)-hz) + (z*r-x*y)); |
| } |
