/* origin: FreeBSD /usr/src/lib/msun/src/k_logf.h */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ /* * See comments in __log1p.h. */ /* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */ static const float Lg1 = 0xaaaaaa.0p-24, /* 0.66666662693 */ Lg2 = 0xccce13.0p-25, /* 0.40000972152 */ Lg3 = 0x91e9ee.0p-25, /* 0.28498786688 */ Lg4 = 0xf89e26.0p-26; /* 0.24279078841 */ static inline float __log1pf(float f) { float hfsq,s,z,R,w,t1,t2; s = f/((float)2.0+f); z = s*s; w = z*z; t1 = w*(Lg2+w*Lg4); t2 = z*(Lg1+w*Lg3); R = t2+t1; hfsq = (float)0.5*f*f; return s*(hfsq+R); }