2 * ====================================================
3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 * Developed at SunPro, a Sun Microsystems, Inc. business.
6 * Permission to use, copy, modify, and distribute this
7 * software is freely granted, provided that this notice
9 * ====================================================
12 #include <sys/cdefs.h>
13 __FBSDID("$FreeBSD$");
16 * float version of __kernel_log(x). See k_log.c for details.
20 /* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */
21 Lg1 = 0xaaaaaa.0p-24, /* 0.66666662693 */
22 Lg2 = 0xccce13.0p-25, /* 0.40000972152 */
23 Lg3 = 0x91e9ee.0p-25, /* 0.28498786688 */
24 Lg4 = 0xf89e26.0p-26; /* 0.24279078841 */
27 __kernel_logf(float x)
29 float hfsq,f,s,z,R,w,t1,t2;
35 if((0x007fffff&(0x8000+ix))<0xc000) { /* -2**-9 <= f < 2**-9 */
36 if(f==0.0f) return 0.0f;
37 return f*f*((float)0.33333333333333333*f-(float)0.5);
51 return s*(hfsq+R) - hfsq;