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/* @(#)s_log2.c 5.1 93/09/24 */
/* Modification from s_exp10.c Yaakov Selkowitz 2009. */
/*
* ====================================================
* 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.
* ====================================================
*/
/*
FUNCTION
<<log2>>, <<log2f>>---base 2 logarithm
INDEX
log2
INDEX
log2f
ANSI_SYNOPSIS
#include <math.h>
double log2(double <[x]>);
float log2f(float <[x]>);
TRAD_SYNOPSIS
#include <math.h>
double log2(<[x]>);
double <[x]>;
float log2f(<[x]>);
float <[x]>;
DESCRIPTION
<<log2>> returns the base 2 logarithm of <[x]>.
<<log2f>> is identical, save that it takes and returns <<float>> values.
RETURNS
On success, <<log2>> and <<log2f>> return the calculated value.
If the result underflows, the returned value is <<0>>. If the
result overflows, the returned value is <<HUGE_VAL>>. In
either case, <<errno>> is set to <<ERANGE>>.
PORTABILITY
<<log2>> and <<log2f>> are required by ISO/IEC 9899:1999 and the
System V Interface Definition (Issue 6).
*/
/*
* wrapper log2(x)
*/
#include "fdlibm.h"
#include <errno.h>
#include <math.h>
#undef log2
#ifndef _DOUBLE_IS_32BITS
#ifdef __STDC__
double log2(double x) /* wrapper log2 */
#else
double log2(x) /* wrapper log2 */
double x;
#endif
{
return (log(x) / M_LOG2_E);
}
#endif /* defined(_DOUBLE_IS_32BITS) */
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