gcc 4.4.2 : float multiplication 4097*4097 seems to be off by 1

0throot 0throot@0throot.com
Fri Nov 12 05:58:00 GMT 2010


In one of my programs, I found a wierd problem with float multiplication. Any
insights you can provide will be very helpful.

The program is as follows,

#include <stdio.h>
int main(void) { float a=4097, b=4097, c=0; c=a*b; printf("%12.2f != %d\n",
c, 4097*4097); return 0; }

The output i get is,

16785408.00 != 16785409

I never thought using float over int could have such adverse effects. 

Is this the correct behavior ? or am i doing something wrong here ?

Following are the system details,

gcc version 4.4.2 20091027 (Red Hat 4.4.2-7) (GCC)
Fedora release 12 (Constantine)
Linux lap.local 2.6.31.5-127.fc12.i686.PAE #1 SMP Sat Nov 7 21:25:57 EST
2009 i686 i686 i386 GNU/Linux

0/
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