sysdeps/libm-ieee754/e_scalb.c

   1 /* @(#)e_scalb.c 5.1 93/09/24 */
   2 /*
   3  * ====================================================
   4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   5  *
   6  * Developed at SunPro, a Sun Microsystems, Inc. business.
   7  * Permission to use, copy, modify, and distribute this
   8  * software is freely granted, provided that this notice
   9  * is preserved.
  10  * ====================================================
  11  */
  12
  13 #if defined(LIBM_SCCS) && !defined(lint)
  14 static char rcsid[] = "$NetBSD: e_scalb.c,v 1.6 1995/05/10 20:46:09 jtc Exp $";
  15 #endif
  16
  17 /*
  18  * __ieee754_scalb(x, fn) is provide for
  19  * passing various standard test suite. One
  20  * should use scalbn() instead.
  21  */
  22
  23 #include "math.h"
  24 #include "math_private.h"
  25
  26 #ifdef _SCALB_INT
  27 #ifdef __STDC__
  28         double __ieee754_scalb(double x, int fn)
  29 #else
  30         double __ieee754_scalb(x,fn)
  31         double x; int fn;
  32 #endif
  33 #else
  34 #ifdef __STDC__
  35         double __ieee754_scalb(double x, double fn)
  36 #else
  37         double __ieee754_scalb(x,fn)
  38         double x, fn;
  39 #endif
  40 #endif
  41 {
  42 #ifdef _SCALB_INT
  43         return scalbn(x,fn);
  44 #else
  45         if (isnan(x)||isnan(fn)) return x*fn;
  46         if (!finite(fn)) {
  47             if(fn>0.0) return x*fn;
  48             else       return x/(-fn);
  49         }
  50         if (rint(fn)!=fn) return (fn-fn)/(fn-fn);
  51         if ( fn > 65000.0) return scalbn(x, 65000);
  52         if (-fn > 65000.0) return scalbn(x,-65000);
  53         return scalbn(x,(int)fn);
  54 #endif
  55 }