Hi y'all, I am trying to read 2 matrices from files, multiply them and print. However, I keep getting error: "can't use string ("1") as an ARRAY ref at line 45" ...can't figure out what the problem is. My code: 

#!/usr/bin/perl -w
use strict;

my $first = $ARGV[0];
my $second = $ARGV[1];
unless (defined($ARGV[0])) {
    print "Insert filename of the first matrix: ";
    chomp($first = <STDIN>);
}
unless (defined($ARGV[1])) {
    print "Insert filename of the second matrix: ";
    chomp($second = <STDIN>);
}

my @AoA;
my $cols = 0;
my $rows = 0;
my @mat1 = readmatrix ($first);
my ($r1, $c1) = ($rows, $cols);
$cols = 0;
$rows = 0;
my @mat2 = readmatrix ($second);
my ($r2, $c2) = ($rows, $cols);

my @product = multiply(\@mat1, \@mat2);

printmatrix (@product);

sub readmatrix {
    my ($file) = @_;
    open(IN, "$file") || die "can't open file: $!\n";
    while (defined (my $line = <IN>)) {
        my @tmp = split(' ', $line);
        $cols = scalar @tmp;
        $rows++;
        push (@AoA, [@tmp]);
    }
    close IN;
}

sub multiply {
    my ($mat1,$mat2) = @_;
    die "unmatching matrices!\n" unless ($c1 eq $r2);
    my $product;
### HERE IS THE BUG SOMEWHERE... ###
    for (my $i=0; $i<$r1; $i++) {
        for (my $j=0; $j<$c2; $j++) {
                    for (my $k=0; $k<$c1; $k++) {
                $product->[$i][$j] += $mat1->[$i][$k] * $mat2->[$k][$j
+];
            }
        }
    }
    return $product;
}

sub printmatrix {
    my (@AoA) = @_;
    for (my $x = 0; $x <= $#AoA; $x++) {
        print join("\t", @{$AoA[$x]}), "\n";
    }
}

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In reply to matrix multiplication by benben

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