perl -MTime::HiRes=gettimeofday,tv_interval -e '$istart=1000;$iend=500
+0;  $t0=[gettimeofday]; for $x($istart..$iend){for $y($istart..$iend)
+{ $x/$y }}; $t1=[gettimeofday]; print "lasted->".tv_interval($t0,$t1)
+."\n"'
[download]

• 1.032998
• 1.029043
• 1.043523
• 1.059354
• 1.034561
• 1.072301
• 1.10864
• 1.034843

• 1.075402
• 1.093403
• 1.089273
• 1.077661
• 1.074203
• 1.091646
• 1.080421

These numbers are seconds.

I couldn't draw any conclusions from this...

I did a similar thing using C:

#include <stdio.h>

#define ITERS 1000000000ul

int main( int argc, char **argv ) {
    __int64 start;
    int i;
    double d;

    getch();

    start = GetTickCount64();

    if( argc > 1 ) {
        printf( "%u integer divisions: ", ITERS );
        start = GetTickCount64();

         for( i = 1; i < ITERS; i++ )
             d = 1 / i;

        printf( "Took %I64d ticks\n", GetTickCount64() - start );
    }
    else {
        printf( "%u integer multiplications: ", ITERS );
        start = GetTickCount64();

         for( i = 1; i < ITERS; i++ )
             d = 1 * i;

        printf( "Took %I64d ticks\n", GetTickCount64() - start );
    }

}
[download]

And on my 64-bit processor, for 32-bit ints I got:

C:\test>muldiv-b 1
1000000000 integer divisions: Took 3432 ticks

C:\test>muldiv-b
1000000000 integer multiplications: Took 2917 ticks
[download]

The numbers vary ~+-30 ticks for individual runs, but division is always ~10% slower than multiplication. I put this down the subsequent promotion of the result to a double rather than the opcode itself.

Conversely, if I use 64-bit ints division is almost 7X slower than multiplication:

C:\test>muldiv-b
1000000000 integer multiplications: Took 3011 ticks

C:\test>muldiv-b 1
1000000000 integer divisions: Took 20764 ticks
[download]

This is think is due to the fact that two 64-bit registers are involved in the result.

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

Yeah, I guess my results show division is a bit slower(on most runs, just on one of 'em it was actually faster)

Maybe it's possible to tell the compiler to not jump to optimizations.

Also, isn't 1*i a bit too easy ?