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Revision 1.9, Thu Oct 9 11:32:48 1997 UTC (26 years, 5 months ago) by lukem
rcsid facism, WARNSify |
/* @(#)s_logb.c 5.1 93/09/24 */ /* * ==================================================== * 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> #if defined(LIBM_SCCS) && !defined(lint) __RCSID("$NetBSD: s_logb.c,v 1.9 1997/10/09 11:32:48 lukem Exp $"); #endif /* * double logb(x) * IEEE 754 logb. Included to pass IEEE test suite. Not recommend. * Use ilogb instead. */ #include "math.h" #include "math_private.h" #ifdef __STDC__ double logb(double x) #else double logb(x) double x; #endif { int32_t lx,ix; EXTRACT_WORDS(ix,lx,x); ix &= 0x7fffffff; /* high |x| */ if((ix|lx)==0) return -1.0/fabs(x); if(ix>=0x7ff00000) return x*x; if((ix>>=20)==0) /* IEEE 754 logb */ return -1022.0; else return (double) (ix-1023); }