Devel::Size is very informative: 
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]
gives these results running on my Alpha with Tru64: 
Double: 24, 24
Array:  168, 408
Matrix: 168, 4488

[download]
So a matrix of 10*10 elements cost 4.5 K, giving 45 bytes pr element - not too bad.

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

In reply to Devel::Size by htoug
in thread why does this array take up so much memory? by Anonymous Monk

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