use strict;
use Data::Dumper;

my @date = qw/ 1.13.04 1.12.04 3.13.04 /;

my @sorted_date =
  map { $_->[0] }                  # retrieve the original date
  sort { $b->[1] <=> $a->[1] }     # sort the normalized date
  map { my @n = /(\d+)\.(\d+)\.(\d+)/; # normalize the date
        my $d = sprintf "%02d%02d%02d", @n[2,0,1];
        [$_, $d] } @date;

print Dumper(\@sorted_date);