my $last_row = 2;
my $last_col = 2;
my $matrix_entry;
my $matrix_value;

for my $row (0 .. $last_row) {
  my $row_frame = $MW->Frame()->pack(-expand => '1',
                                     -fill => 'none',
                                     -side => 'top');
  for my $col (0 .. $last_col) {
    $$matrix_entry[$row][$col] = 
       $row_frame->Entry(-font => 'bold',
                         -width => '3',
                         -relief => 'sunken',
                         -textvariable => $$matrix_entry[$row][$col],
                         )->pack(-side => 'left', padx => '2', pady => '2');
  }
}