$ perl -Mstrict -Mwarnings -le '
    use constant MAX_COLUMN_INDEX => 2;

    secondRoutine(firstRoutine());

    sub firstRoutine{
        my $matrix;

        while (<>) {
            my @fields = split;

            for (0 .. MAX_COLUMN_INDEX) {
                push @{$matrix->[$_]},
                    defined $fields[$_] ? $fields[$_] : "<undef>";
            }
        }

        return $matrix;
    }

    sub secondRoutine {
        my $matrix = shift;

        for my $row (0 .. $#{$matrix->[0]}) {
            for my $col (0 .. MAX_COLUMN_INDEX) {
                print "Row $row Col $col = $matrix->[$col][$row]";
            }
        }

        return;
    }
'
q w e
a s
z
Row 0 Col 0 = q
Row 0 Col 1 = w
Row 0 Col 2 = e
Row 1 Col 0 = a
Row 1 Col 1 = s
Row 1 Col 2 = <undef>
Row 2 Col 0 = z
Row 2 Col 1 = <undef>
Row 2 Col 2 = <undef>