minix/lib/libm/src/w_log2.c

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/* @(#)w_log10.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: w_log2.c,v 1.1 2005/07/21 16:58:39 christos Exp $");
#endif
/*
* wrapper log2(X)
*/
#include "math.h"
#include "math_private.h"
double
log2(double x) /* wrapper log10 */
{
#ifdef _IEEE_LIBM
return __ieee754_log2(x);
#else
double z;
z = __ieee754_log2(x);
if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
if(x<=0.0) {
if(x==0.0)
return __kernel_standard(x,x,48); /* log2(0) */
else
return __kernel_standard(x,x,49); /* log2(x<0) */
} else
return z;
#endif
}