src/math/e_scalb.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35


/* @(#)e_scalb.c 1.3 95/01/18 */
/*
 * ====================================================
 * 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.
 */

#include <math.h>
#include "math_private.h"

double
scalb(double x, double fn)
{
        if (isnan(x)||isnan(fn)) return x*fn;
        if (!isfinite(fn)) {
            if(fn>0.0) return x*fn;
            else       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);
}