open TMP, "datafile.txt" || die ("Could not open data file\n") ;
my @input_data = <TMP> ;
close TMP;

my $record_count = 0;

# Loop through the array
for my $element (@input_data) {

   chomp;
   @first = split(",", $element ) ;

   my $jcount = 0;
   my @result;
   # Loop through the array again

   for my $inside_elem (@input_data) {
        chomp;

        @second = split(",", $inside_elem) ;

        # Build only elements below the diagonal
        last if ( $jcount++ > $record_count  ) ;


        # Covariance logic
        # No issues with the logic
        # sum of products of corresponding elements in the arrays
        $sum = 0;
        $count = 0;
        for (@first) {
            $sum += $_ * $second[$count++] ;
        }
        $sum /= scalar(@first) ;

        push @result, $sum ;
    }
    my $str_to_write =  join(", ", @result)."\n"  ;
    undef @result ;

    # Open the output file handler in append mode.
    open TMP, ">>Outfile.txt" || die ("Could not open output file ");

    print TMP $str_to_write;

    close TMP ;
}