ipiq: Add simple IPI latency measure sysctls (2)
[dragonfly.git] / lib / libm / src / k_logf.h
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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 * $FreeBSD: head/lib/msun/src/k_logf.h 226376 2011-10-15 05:23:28Z das $
12 */
13
14/*
15 * Float version of k_log.h. See the latter for most comments.
16 */
17
18static const float
19/* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */
20Lg1 = 0xaaaaaa.0p-24, /* 0.66666662693 */
21Lg2 = 0xccce13.0p-25, /* 0.40000972152 */
22Lg3 = 0x91e9ee.0p-25, /* 0.28498786688 */
23Lg4 = 0xf89e26.0p-26; /* 0.24279078841 */
24
25static inline float
26k_log1pf(float f)
27{
28 float hfsq,s,z,R,w,t1,t2;
29
30 s = f/((float)2.0+f);
31 z = s*s;
32 w = z*z;
33 t1= w*(Lg2+w*Lg4);
34 t2= z*(Lg1+w*Lg3);
35 R = t2+t1;
36 hfsq=(float)0.5*f*f;
37 return s*(hfsq+R);
38}