I'm interested in your C++ psarse matrix class based on std::map, since I have one too (and it is in Sage in the eclib spkg). If you type CremonaModularSymbols(12345) they are being used.
John On 17 July 2010 10:03, Thierry Dumont <tdum...@math.univ-lyon1.fr> wrote: > Le 17/07/2010 09:22, Martin Rubey a écrit : >> >> William Stein<wst...@gmail.com> writes: >> >>> http://wstein.org/talks/stein-sd24/stein-sd24.pdf >> >> > > Reading this document, I was, among many things, very interested by the 2012 > horizon (Sage 7.0) and specially by the Engineering projects. > I am interested by this point and would like to contribute, if possible. > > My remarks and questions: > > *During the long time I spent with P. Zimmermann and others writing our > book, I tested a large part of the numerical methods. Some things are > lacking, others cannot actually be used, and do not provide an alternative > to Mat*b. But all this can be improved, and the Python basis is very nice. > > Examples: > 1) linear algebra: the support for sparse matrices cannot be used in real > problems: we want to solve large (say 10^5) systems of equations. The > lil_matrix class of Scipy is so slow, that it is a pity. > 2) ODEs: the support provided by scipy is very basic, and insufficient at > least for me. Everything is too old! > I have mostly looked at these points. > > *Question: will (most of) Sage numerical methods remain based on Scipy? > > *How I think we can improve points 1) and 2): > > 1) sparse matrices are created using lil_matrix, based on dictionaries. I > personally use (out of Sage) a C++ class based on std::map which performs > some orders faster. It could be integrated either directly in Sage, or in > Scipy. > > 2) For the ODEs, the best and the most *modern* methods are there: > http://www.unige.ch/~hairer/software.html > H. Hairer, G. Wanner, C. Lubich are among the best specialist of numerical > methods for ODE and their programs (even if written in f77) are wonderful, > and very robust and efficient. Writing an interface may not be a so large > task (there is already a Matlab interface) and we would have the best for > stiff systems, Hamiltonian systems (make celestial mechanics with Sage) and > so on... This would be in the spirit of Sage, I think: use the best software > available, written by true specialists. > > But may be there are already projects (for point 2)) ? let me know... > > Thierry Dumont. > > > > -- > To post to this group, send an email to sage-devel@googlegroups.com > To unsubscribe from this group, send an email to > sage-devel+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/sage-devel > URL: http://www.sagemath.org > -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
