my @another_2D;
for (my $x=0; $x<3; $x++)
{
  for (my $y=0; $y<3; $y++)
  {
     $another_2D[$x][$y]=0;
  }
}
print Dumper \@another_2D;
__END__
prints:
3x3: $VAR1 = [
          [
            0,
            0,
            0
          ],
          [
            0,
            0,
            0
          ],
          [
            0,
            0,
            0
          ]
        ];
# print Dumper \@sq_matrix_3x3; #these both produce the same output
# print Dumper \@another_2D;