pdl> $x = sequence 2,2,3     # "2x2 planar RGB" image, 4 unique colors
pdl> $x = $x-> glue( 0, $x ) # "4x2 RGB" image, 4 unique colors
pdl> $x = $x-> glue( 1, $x ) # "4x4 RGB" image, still 4 unique colors
pdl> $x-> set( 2,2,2, 100 )  # make them 5
pdl> p$x

[
 [
  [0 1 0 1]
  [2 3 2 3]
  [0 1 0 1]
  [2 3 2 3]
 ]
 [
  [4 5 4 5]
  [6 7 6 7]
  [4 5 4 5]
  [6 7 6 7]
 ]
 [
  [  8   9   8   9]
  [ 10  11  10  11]
  [  8   9 100   9]
  [ 10  11  10  11]
 ]
]

pdl> p $x-> clump(2)-> transpose-> uniqvec-> getdim( 1 )
5 

##</code><code>##

use strict;
use warnings;
use feature 'say';
use PDL;

my $x = zeroes 1e8;
my $y = ones   1e8;

$x = $x + $y;     # 1
#$x += $y;        # 2

say qx{ typeperf "\\Process(perl)\\Working Set Peak" -sc 1 }
    =~ /.+"(.+)"/s;

__END__

>perl pdl180504.pl
2427752448.000000

>perl pdl180504.pl
1627779072.000000