Re^4: Kronecker Product

Nice! Interestingly, for this input, the pure Perl solution if faster than my PDL one. But if you make the matrices larger, e.g. already 3x5 and 4x5 makes PDL the fastest, as it scales the best.

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

Comment on Re^4: Kronecker Product Download Code

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Re^5: Kronecker Product
by LanX (Saint) on Jun 21, 2022 at 14:30 UTC

use v5.12;
use warnings;
use Data::Dump qw/pp dd/;


my $X =
  [
   [1, -4, 7],
   [-2, 3, 3]
  ];

my $Y =
  [
   [8, -9, -6,  5],
   [1, -3, -4,  7],
   [2,  8, -8, -3],
   [1,  2, -5, -1]
  ];

pp $X;
pp $Y;

my $X_Y =
  [
   map {
       my $x = $_;
       map {
           my $y = $_;
           [
            map {
                my $xx = $_;
                map { $xx * $_ } @$y
            } @$x
           ]
       } @$Y
   } @$X
  ];

pp $X_Y;
[download]

[[1, -4, 7], [-2, 3, 3]] [[8, -9, -6, 5], [1, -3, -4, 7], [2, 8, -8, -3], [1, 2, -5, -1]] [ [8, -9, -6, 5, -32, 36, 24, -20, 56, -63, -42, 35], [1, -3, -4, 7, -4, 12, 16, -28, 7, -21, -28, 49], [2, 8, -8, -3, -8, -32, 32, 12, 14, 56, -56, -21], [1, 2, -5, -1, -4, -8, 20, 4, 7, 14, -35, -7], [-16, 18, 12, -10, 24, -27, -18, 15, 24, -27, -18, 15], [-2, 6, 8, -14, 3, -9, -12, 21, 3, -9, -12, 21], [-4, -16, 16, 6, 6, 24, -24, -9, 6, 24, -24, -9], [-2, -4, 10, 2, 3, 6, -15, -3, 3, 6, -15, -3], ]
[download]

Cheers Rolf
_{(addicted to the Perl Programming Language :)

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