June 2018 Update

Task/Matrix-arithmetic/Perl/matrix-arithmetic.pl

@@ -0,0 +1,27 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+use PDL;
+use PDL::NiceSlice;
+
+sub permanent{
+	my $mat = shift;
+	my $n = shift // $mat->dim(0);
+	return undef if $mat->dim(0) != $mat->dim(1);
+	return $mat(0,0) if $n == 1;
+	my $sum = 0;
+	--$n;
+	my $m = $mat(1:,1:)->copy;
+	for(my $i = 0; $i <= $n; ++$i){
+		$sum += $mat($i,0) * permanent($m, $n);
+		last if $i == $n;
+		$m($i,:) .= $mat($i,1:);
+	}
+	return sclr($sum);
+}
+
+my $M = pdl([[2,9,4], [7,5,3], [6,1,8]]);
+print "M = $M\n";
+print "det(M) = " . $M->determinant . ".\n";
+print "det(M) = " . $M->det . ".\n";
+print "perm(M) = " . permanent($M) . ".\n";