trouble with modf

[Thomas Kähler]

Hej here,
I am using gcc version 2.95.2 19991024 (release) on an Intel-arch machine
with OS SuSe-Linux 7.1 (kernel 2.4.0) and have  a problem with the 
modf-function, 
it seems to return an uncorrect value. I have written this little program 
to test the function:
/*
 * hugo.c
 */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(int argc, char ** argv[])
{
        double val, comp, predec, postdec;
/***********************************************/
        val = comp = predec = postdec = 0.0;

        val=122.170;
        comp=0.70;
        printf("val=%lf, predec=%lf, postdec= %lf, comp=%lf\n", val, 
predec, postdec, comp);

        postdec = modf(val*10, &predec);

        if ( postdec == comp )
        {
                printf("gotcha!\n");
                val += 0.005;
        }

        printf("val=%lf, predec=%lf, postdec= %lf, comp=%lf\n", val, predec, 
postdec, comp);

        printf("but:\n");
        exit (0);
}
The printf-output shows no differerences between the values of comp and 
postdec.
But then I copied the two variables by memcpy into a buffer and had a 
look at the bytes:
comp showed:    x66 x66 x66 x66 x66 x66 xFFFFFFE6 xEF
postdec showed:         x00 x68 x66 x66 x66 x66 xFFFFFFE6 xEF
How this?
Am I too blind and made a mistake (special headerfile missing ? ) or is 
there a bug in the modf-function?
Thanks in advance!