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/* Utilities for MPFR developers, not exported.
Copyright (C) 1999 PolKA project, Inria Lorraine and Loria
This file is part of the MPFR Library.
The MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
The MPFR Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
License for more details.
You should have received a copy of the GNU Library General Public License
along with the MPFR Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include <math.h>
/* generate a random double using the whole range of possible values,
including denormalized numbers, NaN, infinities, ... */
double drand()
{
double d; int *i, expo;
i = (int*) &d;
d = 1.0;
if (i[0]==0) expo=1; /* little endian, exponent in i[1] */
else expo=0;
i[0] = lrand48();
i[1] = lrand48();
while (i[expo]>=2146435072) i[expo] = lrand48(); /* avoids NaNs */
if (lrand48()%2 && !isnan(d)) d=-d; /* generates negative numbers */
return d;
}
/* returns the number of ulp's between a and b */
int ulp(a,b) double a,b;
{
double eps=1.1102230246251565404e-16; /* 2^(-53) */
if (a==0.0) {
if (b==0.0) return 0;
else if (b<0.0) return 2147483647;
else return -2147483647;
}
b = (a-b)/a;
if (b>0)
return (int) floor(b/eps);
else
return (int) ceil(b/eps);
}
/* return double m*2^e */
double dbl(m,e) double m; int e;
{
if (e>=0) while (e-->0) m *= 2.0;
else while (e++<0) m /= 2.0;
return m;
}
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