#include <stdio.h>
#include <float.h>
#include <math.h>

double sqrt(double);

main()
{
double x, y, r;



*((int*)&x+1) = 0x3d2ffffe;
*(int*)&x = 0x7fffffff;

printf("x                %08X%08X %.16e \n\n", *(((int*)&x) + 1),
*((int*)&x
);

y = sqrt(x);

printf("result           %08X%08X %.16e \n", *(((int*)&y) + 1),
*((int*)&y),

*((int*)&r+1) = 0x3e8fffff;
*(int*)&r = 0x3ffffdbf;
printf("result should be %08X%08X %.16e \n", *(((int*)&r) + 1),
*((int*)&r),

}

It reports the following
x                      3D2FFFFE7FFFFFFF 5.6843378203226540e-14

result                3E8FFFFF3FFFFDC0 2.3841849383641896e-07
result should be 3E8FFFFF3FFFFDBF 2.3841849383641894e-07


The machine is running:


Red Hat Release 6.0 (hedwig)
Kernel 2.2.5-15smp on an i686