[Getfem-users] collaboration between GMM and KDE/Eigen

[Benoît Jacob]

(re-sending because I forgot to CC Ben the first time. Please ignore previous 
e-mail. Sorry about that.)

Hello,

This mail is to propose a collaboration between the GMM project and parts of
the KDE project.

Several subprojects of KDE (kde.org) have identified a common need for linear
algebra functionality. After having considered the existing linear algebra
libraries, we found that we needed to start a new one, which we called Eigen
(eigen.tuxfamily.org). Like GMM, Eigen is a C++ template library.

More recently, a new need has appeared in Krita (koffice.org/krita), that
Eigen can't currently fulfill: sparse matrices and vectors.

Since we see no point in reinventing the wheel, we would like to reuse
existing code for that. After examining the existing libraries, we found that
GMM was the most interesting one from our point of view.

However, using GMM as an external dependency is not optimal for
us, for several reasons:
- additional dependencies are frowned upon by distribution packagers
- we are only interested in a small subset of GMM, and GMM doesn't cover all
of our needs
- we wouldn't like KDE to depend on two different incompatible linear algebra
libraries, especially as there is much feature overlap between them.

So the best solution for us would be, if you allowed us to copy GMM code
directly into Eigen. Eigen is licensed under the GPL plus an exception
allowing any software to use it (much like the GNU C++ STL license, except
that our exception is more liberal). This is very similar in spirit to the
LGPL used by GMM. Of course, if we copy GMM code into Eigen, we will preserve
the GMM authors's copyright lines. But the license will become the
GPL+exception license used by Eigen.

So do you allow us to copy GMM code into Eigen? If yes, we'd probably have a
few questions to ask about the GMM source code.

Conversely, we are planning to implement sparse algorithms that aren't yet
available in GMM, namely sparse least squares:

http://www.stanford.edu/group/SOL/software/lsqr.html

We'd then be happy to back-port them to GMM if you're interested. This way,
our collaboration would be reciprocal :)

Cheers,
Benoit Jacob and Ben Schleimer

PS. Please reply-to-all as we're not subscribed to this mailing list.

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