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http://www.perlmonks.org/index.pl?node_id=134419
Good day, fellow monks. I've got a snippet of code that I'm hoping you can help me speed up. My code is to find the N-th root of a given number.
use Math::BigFloat;
sub Root { my $num = shift; my $root = shift; my $iterations = shift || 5; if ( $num < 0 ) { return undef } if ( $root == 0 ) { return 1 } my $Num = Math::BigFloat->new( $num ); my $Root = Math::BigFloat->new( $root ); my $current = Math::BigFloat->new(); my $guess = Math::BigFloat->new( $num / $root ); my $t = Math::BigFloat->new( $guess ** ( $root - 1 ) ); for ( 1 .. $iterations ) { $current = $guess - ( $guess * $t - $Num ) / ( $Root * $t ); if ( $guess eq $current ) { last } $t = $current**($root-1); $guess = $current; } return $current; }
This uses Newton's method for finding the roots. It produces very accurate results, provided you increase the number of iterations if you're dealing with large numbers and/or large roots. Therein lies the problem.
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