sub rankSums3 {
    my( $aRef, $bRef ) = @_;
    my( $aSum, $bSum ) = (0) x 2;
    my( $a, $b ) = (0) x 2;
    my $rank = 1;
    while( $a < @$aRef && $b < @$bRef ) {
        $aSum += $rank++, ++$a, next if $aRef->[ $a ] < $bRef->[ $b ];
        $bSum += $rank++, ++$b, next if $aRef->[ $a ] > $bRef->[ $b ];
        $aSum += ( $rank * 2 + 1 ) / 2;
        $bSum += ( $rank * 2 + 1 ) / 2;
        $rank += 2;
        ++$a, ++$b;
    }
    $aSum += $rank++ while $a++ < @{ $aRef };
    $bSum += $rank++ while $b++ < @{ $bRef };

    return $aSum, $bSum;
}