#!/usr/bin/perl 
use strict;
use warnings;
use Data::Dumper;
my @a;
my $x = 0;
my $y = 0;
#fill with 0 all the matrix with one loop(no need for two really :) )
$a[$_/8][$_%8]=0 for 0..63;#it's a 7x7 matrix :)
#initialisation of matrix with provided data
$a[0][0]=4;
$a[0][1]=4;
$a[0][2]=4;
$a[0][3]=4;
$a[0][4]=0;
$a[0][5]=0;
$a[0][6]=4;
$a[0][7]=0;
#matrix transpose calculated
while(exists $a[$y][0] && $x<=$y) { 
	# the last condition here is due to not 
	# getting to lower triangle and transposing them 
	# back getting exactly what we started with
        # wich we obviously don't want
	$x = 0; #reset $x for a new pass tghrough the current row
	while(exists $a[0][$x]) {
		($a[$y][$x],$a[$x][$y]) = ($a[$x][$y],$a[$y][$x]) ; 
		#swap the current element to its corresponding position in the transpose
		$x++;#increase the column
	};
	$y++;#increase the row
}