use strict 'vars';
use strict 'subs';
use warnings;

my @matrix1=(
	[1, 2, 3], 
	[4, 5, 6],
	[7, 8, 9]
);
my @matrix2=(
	[2, 4, 6],
	[1, 3, 5], 
	[7, 8, 9]
);
print "matrix1=\n";
for (my $i=0;$i le 2;$i++) {
		for (my $j=0;$j le 2;$j++) {
			print $matrix1[$i][$j]," ";
		}
	print "\n";
}
print "matrix2=\n";
for (my $i=0;$i le 2;$i++) {
		for (my $j=0;$j le 2;$j++) {
			print $matrix2[$i][$j]," ";
		}
	print "\n";
}
my @product=matrix_multiply(@matrix1,@matrix2);
print "product=\n";
for (my $i=0;$i le 2;$i++) {
		for (my $j=0;$j le 2;$j++) {
			print $product[$i][$j]," ";
		}
	print "\n";
}
sub matrix_multiply {
	my ($r_mat1,$r_mat2)=@_;
	my ($r_product);
	my ($r1,$c1)=matrix_count_rows_cols($r_mat1);
	my ($r2,$c2)=matrix_count_rows_cols($r_mat2);

	print $c1,$c2,"\n";
	print $r1,$r2,"\n";
	
	die "matrix 1 has $c1 columns and matrix 2 has $r2 rows>" 
		. " Cannot multiply\n" unless ($c1==$r2);
	for (my $i=0;$i<$r1;$i++) {
		for (my $j=0;$j<$c2;$j++) {
			my $sum=0;
			for (my $k=0;$k<$c1;$k++) {
				$sum+=$r_mat1->[$i][$k]*$r_mat2->[$k][$j];
			}
			$r_product->[$i][$j]=$sum;
		}
	}
	$r_product;
}

sub matrix_count_rows_cols { 
	my ($r_mat)=@_;
	my $num_rows=@$r_mat;
	my $num_cols=@{$r_mat->[0]};
	($num_rows,$num_cols);
}