+++ /dev/null
-/* @(#)k_cos.c 5.1 93/09/24 */\r
-/*\r
- * ====================================================\r
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.\r
- *\r
- * Developed at SunPro, a Sun Microsystems, Inc. business.\r
- * Permission to use, copy, modify, and distribute this\r
- * software is freely granted, provided that this notice\r
- * is preserved.\r
- * ====================================================\r
- */\r
-#include <LibConfig.h>\r
-#include <sys/EfiCdefs.h>\r
-#if defined(LIBM_SCCS) && !defined(lint)\r
-__RCSID("$NetBSD: k_cos.c,v 1.11 2002/05/26 22:01:53 wiz Exp $");\r
-#endif\r
-\r
-/*\r
- * __kernel_cos( x, y )\r
- * kernel cos function on [-pi/4, pi/4], pi/4 ~ 0.785398164\r
- * Input x is assumed to be bounded by ~pi/4 in magnitude.\r
- * Input y is the tail of x.\r
- *\r
- * Algorithm\r
- * 1. Since cos(-x) = cos(x), we need only to consider positive x.\r
- * 2. if x < 2^-27 (hx<0x3e400000 0), return 1 with inexact if x!=0.\r
- * 3. cos(x) is approximated by a polynomial of degree 14 on\r
- * [0,pi/4]\r
- * 4 14\r
- * cos(x) ~ 1 - x*x/2 + C1*x + ... + C6*x\r
- * where the remez error is\r
- *\r
- * | 2 4 6 8 10 12 14 | -58\r
- * |cos(x)-(1-.5*x +C1*x +C2*x +C3*x +C4*x +C5*x +C6*x )| <= 2\r
- * | |\r
- *\r
- * 4 6 8 10 12 14\r
- * 4. let r = C1*x +C2*x +C3*x +C4*x +C5*x +C6*x , then\r
- * cos(x) = 1 - x*x/2 + r\r
- * since cos(x+y) ~ cos(x) - sin(x)*y\r
- * ~ cos(x) - x*y,\r
- * a correction term is necessary in cos(x) and hence\r
- * cos(x+y) = 1 - (x*x/2 - (r - x*y))\r
- * For better accuracy when x > 0.3, let qx = |x|/4 with\r
- * the last 32 bits mask off, and if x > 0.78125, let qx = 0.28125.\r
- * Then\r
- * cos(x+y) = (1-qx) - ((x*x/2-qx) - (r-x*y)).\r
- * Note that 1-qx and (x*x/2-qx) is EXACT here, and the\r
- * magnitude of the latter is at least a quarter of x*x/2,\r
- * thus, reducing the rounding error in the subtraction.\r
- */\r
-\r
-#include "math.h"\r
-#include "math_private.h"\r
-\r
-static const double\r
-one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */\r
-C1 = 4.16666666666666019037e-02, /* 0x3FA55555, 0x5555554C */\r
-C2 = -1.38888888888741095749e-03, /* 0xBF56C16C, 0x16C15177 */\r
-C3 = 2.48015872894767294178e-05, /* 0x3EFA01A0, 0x19CB1590 */\r
-C4 = -2.75573143513906633035e-07, /* 0xBE927E4F, 0x809C52AD */\r
-C5 = 2.08757232129817482790e-09, /* 0x3E21EE9E, 0xBDB4B1C4 */\r
-C6 = -1.13596475577881948265e-11; /* 0xBDA8FAE9, 0xBE8838D4 */\r
-\r
-double\r
-__kernel_cos(double x, double y)\r
-{\r
- double a,hz,z,r,qx;\r
- int32_t ix;\r
- GET_HIGH_WORD(ix,x);\r
- ix &= 0x7fffffff; /* ix = |x|'s high word*/\r
- if(ix<0x3e400000) { /* if x < 2**27 */\r
- if(((int)x)==0) return one; /* generate inexact */\r
- }\r
- z = x*x;\r
- r = z*(C1+z*(C2+z*(C3+z*(C4+z*(C5+z*C6)))));\r
- if(ix < 0x3FD33333) /* if |x| < 0.3 */\r
- return one - (0.5*z - (z*r - x*y));\r
- else {\r
- if(ix > 0x3fe90000) { /* x > 0.78125 */\r
- qx = 0.28125;\r
- } else {\r
- INSERT_WORDS(qx,ix-0x00200000,0); /* x/4 */\r
- }\r
- hz = 0.5*z-qx;\r
- a = one-qx;\r
- return a - (hz - (z*r-x*y));\r
- }\r
-}\r