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#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;
i = (int*) &d;
i[0] = lrand48();
i[1] = lrand48();
if (lrand48()%2) 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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