Speeding up permutations generation
Gene Heskett
gheskett at wdtv.com
Fri Mar 6 05:32:03 EST 2015
On Friday 06 March 2015 03:24:48 Abhiram R wrote:
> > A list of 100 elements has approximately 9.33 x 10**157
> > permutations. If you could somehow generate one permutation every
> > yoctosecond, exhausting them would still take more than a hundred
> > orders of magnitude longer than the age of the universe.
> > --
> > https://mail.python.org/mailman/listinfo/python-list
>
> True that :D I may have exaggerated on the number. Let's consider
> something more practically manageable => 50 elements with a 50!
> permutation.
> Is there a solution now?
Yes, but its now only 8.881784197e+84 elements so it is still not a
practical target. Doing all elements of a matrix is generally equ to
n!, and 50 raised to the 50th power is still a number that will probably
use up this suns remaining lifetime doing it in assembly. If submitted
and accepted to BOINC with its parallelism potential. And
Seagate/Western Digital's combined output for about that same time to
store the result.
I'd choose any other, perhaps less exhaustive method. Or a more
practical size of dataset parameters.
> -Abhiram.R
> *~Never give up*
Cheers, Gene Heskett
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