1/*
2 * ====================================================
3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
4 *
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
8 * is preserved.
9 * ====================================================
10 */
11
12#include <sys/cdefs.h>
13__FBSDID("$FreeBSD$");
14
15/*
16 * Float version of k_log.h.  See the latter for most comments.
17 */
18
19static const float
20/* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */
21Lg1 =      0xaaaaaa.0p-24,	/* 0.66666662693 */
22Lg2 =      0xccce13.0p-25,	/* 0.40000972152 */
23Lg3 =      0x91e9ee.0p-25,	/* 0.28498786688 */
24Lg4 =      0xf89e26.0p-26;	/* 0.24279078841 */
25
26static inline float
27k_log1pf(float f)
28{
29	float hfsq,s,z,R,w,t1,t2;
30
31 	s = f/((float)2.0+f);
32	z = s*s;
33	w = z*z;
34	t1= w*(Lg2+w*Lg4);
35	t2= z*(Lg1+w*Lg3);
36	R = t2+t1;
37	hfsq=(float)0.5*f*f;
38	return s*(hfsq+R);
39}
40