#compare the (s)source patterns
for ( my $i=0 ; $i<$row ; $i++ )
        {
        #for each column in a row
        print "number of cols= $#{s1[$i]}\n";
        if ($j=0;$j<$#{s1[$i]};$j++)
           {
           if (s1[i][j]==s1[i+1][j+1]){print "$i,$j\n";
           }
        }