example of a 3x3:
my @m = ([0,0,0],
         [0,0,0],
         [0,0,0]);

##</code><code>##

#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my @sq_matrix_3x3;

my @list = (1,2,3);
foreach (@list)        
{
    push (@sq_matrix_3x3, [0,0,0]); #creates a row with 3 elements
}
print "3x3 Matrix: ";
print Dumper \@sq_matrix_3x3;

##</code><code>##

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;