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/* origin: FreeBSD /usr/src/lib/msun/src/e_scalb.c */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunSoft, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
* scalb(x, fn) is provide for
* passing various standard test suite. One
* should use scalbn() instead.
*/
#define _GNU_SOURCE
#include <math.h> // for scalbn, isnan, rint, isfinite
double scalb(double x, double fn)
{
if (isnan(x) || isnan(fn))
return x * fn;
if (!isfinite(fn)) {
if (fn > 0.0)
return x * fn;
return x / (-fn);
}
if (rint(fn) != fn)
return (fn - fn) / (fn - fn);
if (fn > 65000.0)
return scalbn(x, 65000);
if (-fn > 65000.0)
return scalbn(x, -65000);
return scalbn(x, (int)fn);
}
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