a =. i. 2 3 4 5
b =. i. 2 4 3 5 6
$a *"0 _ b
2 3 4 5 2 4 3 5 6
$+/"6 +/"4 a *"0 _ b
2 3 5 2 3 5 6
R.E. Boss
> -----Oorspronkelijk bericht-----
> Van: Programming <[email protected]>
> Namens [email protected]
> Verzonden: donderdag 6 februari 2020 23:39
> Aan: [email protected]
> Onderwerp: Re: [Jprogramming] multiply two multidimensional matrices
>
(...)
>
> C_ijlmnop = sum_k A_ijkl * B_mknop
>
> means I have C with rank 7, A with rank 4 and B with rank 5.
> C_ijlmnop is a *number*, the same with A_ijkl and B_mknop (for any given
> set of allowed indices).
> The equation above determines all atoms of C (all components of C) as a
> function of atoms of A and B. The multiplication *is* between numbers (or
> atoms, if you like).
>
> [The prescription can also be understood as, first, making an outer product of
> A and B leading to rank-9 object, then contracting together 2 indices, leading
> to a rank-7 object (tensor).]
>
> What is not clear with this?
>
>
> > To start with I want to know: Does my example do what you want it to do?
>
> I will check if it does what I want.
>
>
> Thanks!
> Ruda
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