Re: [R] Multiple matrix multiplication with two 3-dimensional arrays

From: Anupam Tyagi <AnupTyagi_at_yahoo.com>
Date: Sat 09 Sep 2006 - 05:11:57 GMT

Sophie Baillargeon <Sophie.Baillargeon <at> mat.ulaval.ca> writes:

> Maybe I could use an "apply" or something but I
> can't figure out how. I would have hoped that simply doing
>
> array1%*%array2
>
> would work, but it doesn’t…

I think one of the issues is that algebra for N-Dimentional arrays are not well defined. Think how would you define the above operartion on two 3x3x3 arrays. I had seen a paper a couple of years ago in some math journal that had proposed an algebra. I will be interested in knowing a reference to some source that defines 3-dimentional array algebra. Then perhaps it could be implemented in R.

I will also be interested in knowing what is the equivalent of "cell" array in MATLAB in R---that is something that is equivalent to the "cell" functions in a spreadsheet---sometimes this can be useful.

Anupam.



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