@a = (1, 2, 3);
@b = (4, 5, 6);

sub addem
{
    my ($reference1, $reference2) = @_;
    for ($loop_index = 0; $loop_index <= $#$reference1; $loop_index++) {
        $result[$loop_index] = @$reference1[$loop_index] + @$reference2[$loop_index];
    }
    return @result;
}

@array = addem (\@a, \@b);
print join (', ', @array);