use strict;
use Devel::Size qw(size total_size);
my $double;
my @array;
my @matrix;

$double = 1.0;

for my $x (0..9) {
  $array[$x] = 1.0;
  for my $y (0..9) {
    $matrix[$x][$y] = 1.0;
  }
}


print "Double: ", size(\$double), ", ", total_size(\$double), "\n";
print "Array:  ", size(\@array), ", ", total_size(\@array), "\n";
print "Matrix: ", size(\@matrix), ", ", total_size(\@matrix), "\n";
[download]

Double: 24, 24
Array:  168, 408
Matrix: 168, 4488
[download]

Try other sizes for yourself, and go either the PDL or the Inline::C way, as others have recommended.