Re: Fast matrix multiplication

Interestingly, this came up today on perl.com's entry from the Perl Cookbook.

Use PDL, which overloads the '*' operator (among others) to multiply a matrix.

----
I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer

Note: All code is untested, unless otherwise stated

Comment on Re: Fast matrix multiplication

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Re^2: Fast matrix multiplication by etj (Priest) on Feb 20, 2022 at 15:25 UTC
In PDL, '' is for scalar multiplication, which automatically "broadcasts" up so that two ndarrays can be scalar-multiplied so the result is each of the six "slots" being the product of the two numbers. Matrix multiplication is the overload of the 'x' operator. `pdl> p $x = sequence(2,2) [ [0 1] [2 3] ] pdl> p $y = sequence(2,2) + 3 [ [3 4] [5 6] ] pdl> p $x $y [ [ 0 4] [10 18] ] pdl> p $x x $y [ [ 5 6] [21 26] ]` [download]	[reply] [d/l]

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Re^2: Fast matrix multiplication
by etj (Priest) on Feb 20, 2022 at 15:25 UTC

pdl> p $x = sequence(2,2)
[
 [0 1]
 [2 3]
]

pdl> p $y = sequence(2,2) + 3
[
 [3 4]
 [5 6]
]

pdl> p $x * $y
[
 [ 0  4]
 [10 18]
]

pdl> p $x x $y
[
 [ 5  6]
 [21 26]
]
[download]

[reply]
[d/l]