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From Kim van der Linde <...@kimvdlinde.com>
Subject Re: [math] Matrix subMatrix and mean methods
Date Sun, 03 Oct 2004 15:38:10 GMT


Phil Steitz wrote:

> I agree here as well. Do you see use cases where you will want to start 
> with a double[][] array, perform matrix operations on it (say some 
> decomposition) and then run stats on the resulting matrix? Will it be 
> too onerous to make copies of the double[][] at each stage?  If so, we 
> need to think about access to the double[][].

I think keeping getData() will do the job. I generally do not like to 
store the result of a calculation in the original matrix, it always 
confuses me. If the content is of a different type, the name should be 
different.

>> Is there the intention to add an EigenvalueDecomposition class to the 
>> package? In that case, which algorithm is targeted to be used? Jacobi?
> 
> We have not discussed this. Feel free to add to the wish list and 
> propose an algorithm. We also need to discuss how best to implement the 
> strategy pattern for decompositions in general, as there will often be 
> multiple algorithms to choose from.

I have plugged in the EigenvalueDecomposition class from JAMA, which 
works fine for the PCA and CPCA modules. They do have a whole set of 
decompositions, and they might be easy to implement in the package (if 
they are free to be used).

Kim

-- 
http://www.kimvdlinde.com

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