in reply to Algorithm for cancelling common factors between two lists of multiplicands
Unless the individual values get very large, I think the easiest would be to factor them:
sub combine_factors { my $list = shift; my $factors = {}; for (@$list) { for (factors($_)) { ++$factors->{$_}; } } $factors; } my $fa = combine_factors(\@a); my $fb = combine_factors(\@b); ($fa->{$_} ||= 0) -= $fb->{$_} for keys %$fb; my @c = map +($_) x $fa->{$_}, grep $fa->{$_} > 0, keys %$fa; my @d = map +($_) x -$fa->{$_}, grep $fa->{$_} < 0, keys %$fa;
This has the disadvantage that it will leave a list of primes: @c == (3, 5, 11), @d == (2, 2, 2, 23). I'm not sure how you'd retain the original composites (or parts thereof), nor how you'd define which composites to keep, so I chose to ignore that aspect of it.
Hugo
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Re^2: Algorithm for cancelling common factors between two lists of multiplicands
by BrowserUk (Patriarch) on Aug 08, 2005 at 20:20 UTC | |
by hv (Prior) on Aug 09, 2005 at 00:07 UTC | |
by BrowserUk (Patriarch) on Aug 09, 2005 at 00:27 UTC | |
by hv (Prior) on Jun 10, 2022 at 17:19 UTC |
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