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( #3333=superdoc: print w/replies, xml ) Need Help??
You might also try this :
sub Root2 { my $num = shift; my $root = shift; my $iterations = shift || 10; if ( $root == 0 ) { return 1 } if ( $num < 0 ) { return undef } my $current = Math::BigFloat->new(); my $guess = Math::BigFloat->new( $num / $root ); my $t=Math::BigFloat->new($guess**($root-1)); 1st version : WRONG ! sh +ould be in the loop. for ( 1 .. $iterations ) { $current = $guess - ( $guess * $t - $num ) / ( $root * $t ); if ( $guess eq $current ) { last } $t=Math::BigFloat->new($current**($root-1)); $guess = $current; } return $current; }
The idea behind, is that '**' is MUCH slower than '*', so I exchange 2 '**' for one '**' and 2 '*'
It seems indeed to speed things alot :
(I'm sure your numerous tests will make it sure ;-)
timethese(10,{ 'Root'=> sub {Root(1000,60)}, 'Root2'=> sub {Root2(1000,60)}});

gives as result :

  Benchmark: timing 10 iterations of Root, Root2...
    Root: 104 wallclock secs (104.38 usr + 0.01 sys = 104.39 CPU) @ 0.10/s (n=10)
    Root2: 15 wallclock secs (14.75 usr + 0.00 sys = 14.75 CPU) @ 0.68/s (n=10)
    Root2: 97 wallclock secs (92.67 usr + 0.16 sys = 92.83 CPU) @ 0.11/s (n=10)

Corrected my code! I misplaced the $t calculation outside the loop,
which is wrong beccause $guess change inside the loop.
As you can see it's no more so fast...

"Only Bad Coders Code Badly In Perl" (OBC2BIP)

In reply to <strike>6 times faster?</strike> (Re: Help w/ Code Optimization) by arhuman
in thread Help w/ Code Optimization by sifukurt

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