On 10/26/12 8:47 AM, P Purkayastha wrote:
That raises a problem that I see with the current use of RR. What is the reason behind using RR instead of RDF/CDF by default? I have been going through the various methods available when doing M.<tab>. A lot more methods have been implemented for RDF compared to RR. Although a huge range of methods seem "available", most of the interesting ones don't work for RR. Quite a number of them, but less than RR, also don't work for RDF.
For most computations in Sage, using RR gives better results. The problem is that no one has implemented numerically stable linear algebra algorithms for RR/CC/RealField/ComplexField (well, I guess at one point I had a numerically stable LU decomposition with partial pivoting, but I'm not sure if that ended up getting committed or not).
Sergey Bochkanov was working on implementing an interface to alglib [1] to make numerically stable multiprecision linear algebra available: https://groups.google.com/forum/?fromgroups=#!topic/sage-devel/0sBNEuFCfCs (search also sage-devel for 'alglib' or posts from Sergey for longer threads on the subject).
I'd say finishing the interface with alglib (and evaluating the quality of alglib) would be a very good project for someone to do.
Thanks, Jason [1] http://www.alglib.net/ -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To post to this group, send email to sage-devel@googlegroups.com. To unsubscribe from this group, send email to sage-devel+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel?hl=en.
