Calculating the (7, 4) Hamming code

The following program illustrates matrix multiplication with PDL, as well as transposing, modulo a number, and retrieving the values from a pdl as a Perl array.

#!/home/ben/software/install/bin/perl
use warnings;
use strict;
use PDL;

my $g = pdl [
    [1, 0, 0, 0],
    [0, 1, 0, 0],
    [0, 0, 1, 0],
    [0, 0, 0, 1],
    [1, 1, 1, 0],
    [0, 1, 1, 1],
    [1, 0, 1, 1],
];

for (0..15) {
    my @r;
    # Make the array of bits
    for my $x (0..3) {
        $r[3 - $x] = (int ($_ / (1 << $x))) % 2;
    }
    my $s = pdl (\@r);
    # Multiply by $g.
    my $t = $g x transpose ($s);
    # Modulo all values by 2.
    $t = $t % 2;
    # Get the bits out again.
    my @bits = $t->list ();
    # Print.
    print join ('', @bits), "\n";
}

(download)

0000000
0001011
0010111
0011100
0100110
0101101
0110001
0111010
1000101
1001110
1010010
1011001
1100011
1101000
1110100
1111111