On 5/21/06, Luc Maisonobe <[EMAIL PROTECTED]> wrote:
Hello,
I am the creator of the Mantissa library
(http://www.spaceroots.org/software/mantissa/index.html), a Java library
providing some mathematical algorithms.
Mantissa provides several algorithms that could be useful for
Commons-Math. I think the objectives of the two libraries are quite
similar, but I don't know (yet) the point were you consider "commons
problems" addressed by Commons-Math end and where problems are
considered too specific to be provided here.
I would be very glad to donate parts of Mantissa code to Commons-Math if
you wish so. Mantissa is released under a revised-BSD type license, but
I am quite happy with Apache license too and ready to change.
I don't think everything in Mantissa is useful for Commons-Math. IMHO,
the most interesting parts are :
- the estimation package
Gauss-Newton estimator (based on LU decomposition),
Levenberg-Marquardt estimator (based on QR decomposition)
- the fitting package (curve fitting, using the estimation package)
- the Ordinary Differential Equations package
this is clearly THE best package in Mantissa, with several
state of the art integrators with fixed steps, variable stepsize
(including Dormand-Prince 8 (5,3) and Gragg-Bulirsch-Stoer),
all of them supporting continuous output and multiple switching
functions (can be used for G-stop, but not limited to that), well
tested and used
- the roots package
provides a Brent algorithm when the derivatives are not available
Some package that may be interesting are :
- the geometry package
mainly for the 3D rotations implementations using quaternions
internally and axes/angles, Cardan angles, Euler angles, matrices,
single or double vectors pairs and quaternions in the interface
- the functions package
providing notions like computable or sampled functions
- the quadrature package
(Riemann, trapezoid, enhanced Simpson, Gauss-Legendre up
to 5 points, easily extended)
- the utilities package
for the array mapping paradigm
Some package that are probably not interesting are :
- the algebra package
orthogonal polynomials, inefficient and awkward implementation
- the raw linear algebra package
basic implementation developped for speed ... not sure the goal was
achieved and using only straightforward algorithms, not state of the art
- the random number generators
supports correlated vectors generation
Luc.
First, thanks for your interest in joining forces. We are always
looking for new contributors / collaborators at apache. There are
certainly lots of things in the list above that would fit nicely in
commons-math or complement things that we have in development. What
is most important to us here, as everywhere @apache, is that we grow
community around the code, not just the code itself. So if your
interest is in bringing in code and maybe more contributors and
working on it here, then that will be great. If you just want to
donate / relicense the code, then while we really appreciate your
thinking of us, what we can adopt and support will of necessity be
pretty limited. I really hope you will consider getting involved
personally (as you have already ;-) and bringing in contributions as
we talk about them and they make sense. Other collaborators are most
welcome as well.
One housekeeping thing that we need to consider before we start to
have real fun with Mantissa is to make sure that you *can* relicense
and contribute portions of this code to apache. Please have a look at
the sections on this page http://www.apache.org/licenses/#clas on CLAs
and Software Grants. If you and / or other Mantissa team members
decide to contribute code to Apache based on Mantissa, you will need
to be able to sign CLAs and, depending on how the code comes in,
possibly a Software Grant (if we bring in a substantial amount of code
in a lump instead of small, refactored bits incrementally, we need to
do the Grant). Don't worry about the process stuff, I can handle
that. The important thing is to make sure that a) you want to join
the community and b) you can comply with the CLA and freely donate
contributions. Feel free to ask questions here or offline.
Once again, thanks for your interest in commons-math and we look
forward to working with you!
Phil
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