my $element = $matrix[0]->[4]; 
# or by shorthand:
my $element2 = $matrix[0][4];

##</code><code>##

$matrix[6]->[3] = 8; # or the same shorthand as above

##</code><code>##

my @row6 = @{ $matrix[6] }; # to a list
my $listRef6 = $matrix[6]; # to a listreference

##</code><code>##

foreach my $row (@matrix) {
  print join ("\t", @$row);
}