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Re: Algorithm for cancelling common factors between two lists of multiplicands

by tlm (Prior)
on Aug 09, 2005 at 13:53 UTC ( #482213=note: print w/replies, xml ) Need Help??


in reply to Algorithm for cancelling common factors between two lists of multiplicands

Here's a another solution. It takes two array refs, makes copies of them, and cancels out common terms, removing all 1's.

sub list_reduce { my ( $top, $bot ) = map [ grep $_ != 1, @$_ ], @_; die "Bad data\n" if ( grep $_ < 1, @$top, @$bot ); OUTER: for my $i ( reverse 0 .. $#$top ) { for my $j ( reverse 0 .. $#$bot ) { ( $top->[ $i ], $bot->[ $j ] ) = reduce( $top->[ $i ], $bot->[ $ +j ] ); splice @$bot, $j, 1 if $bot->[ $j ] == 1; if ( $top->[ $i ] == 1 ) { splice @$top, $i, 1; next OUTER; } } } return ( $top, $bot ); } sub reduce { my ( $top, $bottom ) = @_; my $gcd = Math::BigInt::bgcd( $top, $bottom ); return ( $top/$gcd, $bottom/$gcd ); }


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