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From Ted Dunning <>
Subject Re: [MATH] Re: Sparse matrices not supported anymore?
Date Sun, 13 Oct 2013 15:14:40 GMT
On Sun, Oct 13, 2013 at 5:17 AM, Gilles <>wrote:

> Most sparse matrices just punt and say they are sorry in a very
>> non-IEEE-754 sort of way.
> How do they do that, practically?

Sorry, I was being cute.

What I mean is that they libraries implement a sparse matrix operation and
don't care what results are produced if Inf's are used.

> Commons Math has decided instead to remove sparse matrices entirely.
> IIRC, this decision was taken by default, because nobody was identified
> as a user of CM's sparse matrices implementation. We thus concluded that
> it was harmless to drop this part of the code because it needed work (cf.
> issues clearly explained above) and we are lacking human resources to
> perform it (i.e. we need developers interested to fix and maintain this
> part of the code). If such a person would come forward, the decision
> could probably be reverted.

This is a key point. Developers and use cases are critical to having open
source software.

It should also be noted that there are solutions for sparse operations in
Mahout and other libraries.  Mahout, in particular, lacks much of the other
algorithms that Commons Math has and is focussed on what math operations
are needed to support Mahout algorithms.  But if you need sparse matrices,
that may be enough.

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