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 );
}