$"x=$%="@ARGV";$~=$;='(  +)';while($%>>$:++){if($"=~/$~$/^$"=~/$;$/){$
|=$?=$:>2||die"prime\n";eval"print length(\$$?)".($:>++$?&&"/length(\$
$?).'*'")while$:>$?;die$/}$;=$~;$~=~s~.*~^($&\\1+)~;$~=~s;\d+;1+$&;eg}

[download]

The best thing I can say about this code is that it works. It will take a number via argv give you the prime factorization of that number... eventually. It's not very efficient. At all. I had a lot of fun writing it, but it's really bad at what it does. To give you an idea of how erratic it is, here are some benchmarks:

<Reveal this spoiler or all in this thread>

While it can distinguish primes at a reasonable rate, it takes a really long time to factor composite numbers. Particularly composite numbers made up of several small primes. Powers of 2 are the worst-case scenario.

for$b(-25..25){for$a(-50..29){$x=$a/21;$y=$b/15;print$b?chr:chr^chr
ord(substr'<6C}'.1x29 .'[FDEq2?@E96Cqa6C=q924',$a)-49;$_=30;($y,$x)
=(2*$x*$y+$b/15,$x*$x-$y*$y+$a/21)while$x*$x+$y*$y<9&$_++<95}$_=10}

[download]

In reply to How not to do prime factorization by thisisdada

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