Re^2: Kronecker Product

It doesn't work for the larger example from Wikipedia:

my $X = pdl([1, -4, 7],
             [-2, 3, 3]);
my $Y = pdl([8, -9, -6,  5],
            [1, -3, -4,  7],
            [2,  8, -8, -3],
            [1,  2, -5, -1]);
my $XY =pdl([  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]

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

Comment on Re^2: Kronecker Product Select or Download Code

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Re^3: Kronecker Product by LanX (Saint) on Jun 21, 2022 at 11:34 UTC
that's because he hardcoded `$x->[0]` and `$x->[1]` here a generic version `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; for my $x ( @$X ) { for my $y ( @$Y ) { push @$X_Y, [ map { my $xx = $_; map { $xx * $_} @$y } @$x ]; } } pp $X_Y;` [download] `[[1, -4, 7], [-2, 3, 3]] [[8, -9, -6, 5], [1, -3, -4, 7], [2, 8, -8, -3], [1, 2, -5, -1]] [ [8, -9, -6, 5, -32, 36, 24, -20, 56, -63, -42, 35], [1, -3, -4, 7, -4, 12, 16, -28, 7, -21, -28, 49], [2, 8, -8, -3, -8, -32, 32, 12, 14, 56, -56, -21], [1, 2, -5, -1, -4, -8, 20, 4, 7, 14, -35, -7], [-16, 18, 12, -10, 24, -27, -18, 15, 24, -27, -18, 15], [-2, 6, 8, -14, 3, -9, -12, 21, 3, -9, -12, 21], [-4, -16, 16, 6, 6, 24, -24, -9, 6, 24, -24, -9], [-2, -4, 10, 2, 3, 6, -15, -3, 3, 6, -15, -3], ]` [download] Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery} updates cleaned up code addded output	[reply] [d/l] [select]
Re^4: Kronecker Product by choroba (Cardinal) on Jun 21, 2022 at 12:32 UTC
Nice! Interestingly, for this input, the pure Perl solution if faster than my PDL one. But if you make the matrices larger, e.g. already 3x5 and 4x5 makes PDL the fastest, as it scales the best. `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l]
Re^5: Kronecker Product by LanX (Saint) on Jun 21, 2022 at 14:30 UTC
Just for fun, a solution with nested maps only ... :) `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 :) Wikisyntax for the Monastery}	[reply] [d/l] [select]

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