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From Sam Halliday <>
Subject Re: [math] Re: commons-math, matrix-toolkits-java and consolidation
Date Thu, 14 May 2009 20:54:26 GMT

Replies inline:

Ted Dunning wrote:
>> As a start, I'd like to discourage the use of a solid implementation for
>> SparseReal{Vector, Matrix}... please prefer an interface approach,
>> allowing
>> implementations based on the Templates project:-
> Can you say more about what aspects of the Templates project you feel are
> important?  You mention one case of storage layout.

It's difficult to say which algorithms from Templates ones are the most
important ones, but in most cases reference implementations already exist
(usually in fortran) and should be preferred (e.g. by using f2j with a
wrapper layer): the theory can be quite involved. MTJ only touches the
surface! However, an important step is recognising that there are not just
"dense" and "sparse" matrices... but whole classes of structured sparse

Ted Dunning wrote:
>> I believe commons-math should move to a netlib-java backend (allowing the
>> use of machine optimised BLAS/LAPACK).
> This is an interesting suggestion.  Obviously adopting MTJ wholesale would
> accomplish that.
> Can you say something about the licensing issues if we were to explore,
> for
> discussion sake, MTJ being folded into commons-math?  MTJ is LGPL while
> commons has to stay Apache licensed.  This licensing issue has been the
> biggest sticking point in the past.

I personally have no problems with my MTJ contributions being released
Apache. Bjorn-Ove is the person to talk to about the bulk of MTJ. I'll ask

MTJ depends on netlib-java, which is technically a translation of the
original netlib libraries. They are BSD license. I seriously doubt you'll
get them to give you the right to redistribute as, so you'll have to decide
if that's a blocker.

What would "adopting wholesale" mean? It would be a good opportunity to
review/revise parts of the API and find duplication with the rest of the
commons-math project.
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