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Re: simplicity vs. efficiency of algorithms in GSL
Hi Everybody,
On 26.09.2008, at 23:45, Brian Gough wrote:
At Wed, 24 Sep 2008 18:07:20 -0600, Gerard Jungman wrote:
Sounds reasonable. I'm tired of waiting for them to produce
something attractive. But what do we do?
I think we should continue with simple linear algebra
implementations until there is a major change in the state of the
art, like being able to generate all LAPACK routines automatically
with the FLAME tools or similar.
Of course, I like things to be neat and tidy; that's just me. Maybe
other people don't mind having to cobble things together, but I
have a very low threshold for that. There's no work I do that is so
compelling that I don't care how painful it is to get the answer.
And I always want better tools.
The history of the field, and computing in general, doesn't give
much cause for optimism here unfortunately.
I really like GSL and use it a lot -- from C++ and from Python.
I also was involved in early efforts to create a Python layer (PyGSL)
and still use that a lot, i.e. for special functions and to get the
constants.
In C++ I am using mostly ODE solvers, linear algebra, local optimizers
(plus sf and const again, of course).
It does bother me (and colleagues) a lot that neither the ODE solvers
nor the LA routines are really up to speed. My colleagues and myself
are really considering to abandon the GSL because we want better ODE
solvers and better eigenvalue/vector routines! And if the crucial
parts are not from GSL, why us it at all?
The name GNU Scientific Library implies it is meant for scientific
computing. Well, computational science (turned words around on
purpose), to a large extent, is solving large-to-big problems. Really
big problems probably have the resources to put together the best
algorithms for all their needs. For large problems that is often not
the case: We often implement the programs as a single person.
There, we need the best libraries around. We like GSL, because it is
nicely documented and delivers routines for many (most) problems.
However, we are very much in need of getting improved algorithms!
For LA I would be very much in favor to have people (re)implement or
wrap fractions of LAPACK with a GSL-style interface. If there would be
a single nicely implemented routine, others would be easy to add.
For ODE, for example, I am considering to test, and eventually switch
to, cvode (but I have not used it at all so far). I would be very
happy to not need to do this, but instead get improved ODE routines in
GSL and use my time for doing science!
Please take this as a call that scientists need improved routines in a
GSL-quality and -breadth library.
I understand that this is a difficult problem, but that is what GSL
should aim at and what the FSF should support and push if they want a
scientific library!
Regards,
Jochen
--
Fritz-Haber-Institut der MPG -- Department of Molecular Physics --
Manipulation of Large Molecules
Faradayweg 4-6 (C1.03)
D-14195 Berlin, Germany
phone: +49-30-84135686
fax: +49-30-84135892
http://www.fhi-berlin.mpg.de/mp/jochen