Re^5: Behold! The power of recursion.

Replies are listed 'Best First'.
Re^6: Behold! The power of recursion. by Roy Johnson (Monsignor) on Apr 08, 2005 at 21:39 UTC
Ironically, the recursive form (just leave out "goto") is much faster. It's a little hard to tell using factorial, but you can see it in this: `sub rec_max { return () unless @_; my ($h1, $h2) = (shift, shift); if (@_) { unshift @_, ($h1 > $h2) ? $h1 : $h2; &rec_max; # Try it with and without goto here } elsif (defined $h2) { return ($h1 > $h2) ? $h1 : $h2; } } use List::Util 'shuffle'; print rec_max shuffle(1..2000,1500..3000,3500..8000);` [download] Maybe someone else can explain that. Caution: Contents may have been coded under pressure.	[reply] [d/l]
Re^7: Behold! The power of recursion. by ikegami (Patriarch) on Feb 17, 2006 at 23:17 UTC
Indeed! Benchmark results: `Rate uses_goto normal uses_amp uses_goto 94719/s -- -10% -14% normal 105040/s 11% -- -4% uses_amp 109823/s 16% 5% -- Rate uses_goto normal uses_amp uses_goto 94448/s -- -8% -14% normal 103141/s 9% -- -7% uses_amp 110408/s 17% 7% -- Rate uses_goto normal uses_amp uses_goto 94148/s -- -11% -14% normal 105616/s 12% -- -4% uses_amp 109985/s 17% 4% --` [download] Benchmark code: Read more... (746 Bytes)	[reply] [d/l] [select]
Re^8: Behold! The power of recursion. by diotalevi (Canon) on Feb 18, 2006 at 00:26 UTC
Manually optimize the tail call away yourself and get a very nice improvement in speed. I switched back to your node's parent's code because it was recursive and yours wasn't. I haven't decided where exactly recursion is so utterly losing `Rate normal goto amp unrolled normal 7.91/s -- -75% -91% -95% goto 31.9/s 304% -- -63% -81% amp 85.5/s 981% 168% -- -50% unrolled 169/s 2044% 431% 98% --` [download] Read more... (2 kB) ⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊	[reply] [d/l] [select]
Re^9: Behold! The power of recursion. by BrowserUk (Patriarch) on Feb 18, 2006 at 04:53 UTC


Don't ask to ask, just ask
	PerlMonks