diff options
Diffstat (limited to 'modules/fdlibm/src/k_logf.h')
-rw-r--r-- | modules/fdlibm/src/k_logf.h | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/modules/fdlibm/src/k_logf.h b/modules/fdlibm/src/k_logf.h new file mode 100644 index 0000000000..7ad1afd4c4 --- /dev/null +++ b/modules/fdlibm/src/k_logf.h @@ -0,0 +1,39 @@ +/* + * ==================================================== + * 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. + * ==================================================== + */ + +//#include <sys/cdefs.h> +//__FBSDID("$FreeBSD$"); + +/* + * Float version of k_log.h. See the latter for most comments. + */ + +static const float +/* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */ +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 +k_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); +} |