use strict;
use warnings;
use feature 'say';
use PDL;
use Time::HiRes 'time';

use constant DIM => 80;
my $x = random DIM, DIM;
my $y = random DIM, DIM;

report( 'choroba, vr', \&kronecker_product, $x, $y );
report( 'etj', \&kron, $x, $y );

sub report {
    my ( $monk, $code, $x, $y ) = @_;
    
    my $t = time;
    my $k = $code-> ( $x, $y );
    say "$monk:";
    say 'time: ', time - $t; 
    say 'memory: ', mem();
}

sub mem {
    qx{ typeperf "\\Process(perl)\\Working Set Peak" -sc 1 } 
        =~ /(\d+)\.\d+\"$/m;
    ( my $s = $1 ) =~ s/(\d{1,3}?)(?=(\d{3})+$)/$1,/g;
    return $s
}

sub kronecker_product {
    use PDL::NiceSlice;
    my ( $x, $y ) = @_;

    ( $x( *1, *1 ) * $y )
        -> clump( 0, 2 )
        -> clump( 1, 2 )
}

sub PDL::dupN {
  my ($this, @times) = @_;
  return $this->copy if !grep $_ != 1, @times;
  my $sl = join ',', map ":,*$_", @times;
  $this = $this->slice($sl);
  $this = $this->clump($_, $_+1) for 0..$#times;
  $this;
}

sub PDL::inflateN {
  my ($this, @times) = @_;
  return $this->copy if !grep $_ != 1, @times;
  my $sl = join ',', map "*$_,:", @times;
  $this = $this->slice($sl);
  $this = $this->clump($_, $_+1) for 0..$#times;
  $this;
}

sub kron { my ($x,$y) = @_; $x->inflateN($y->dims) * $y->dupN($x->dims) }

__END__

choroba, vr:
time: 0.0958220958709717
memory: 355,741,696
etj:
time: 8.45677018165588
memory: 2,977,234,944