Dimitri Pourbaix a écrit : > Luc, > >> Concerning MATH-321, the partial fix I proposed has been withdrawn by >> the complete rewrite of SVD. >> This partial fix also was not considered mathematically sound by Dimitri >> since the dimensions of the matrices did not match complete SVD. Well, >> this was in fact desired as MATH-321 explicitly asks for non-full SVD. >> >> So I'm not sure anymore what we need to do. If we follow Dimitri's >> rationale, we should close this as WON'T FIX. If we decide to fix it, I >> think we should postpone it to after 2.1 to have time to decide how we >> solve it. SVD has already been vastly improved by Dimitri's work, so I >> would really much like to see it published now. >> >> Dim, what do you think about this ? > > The version I uploaded does not benefit from any sparsity of the matrix > to be decomposed. I have not looked at any algorithm for this kind of > matrix as it would likely involve a different way of storing the matrix > itself. I agree to put "WON'T FIX" for 321 unless someone can come up > with an example showing that that, for a sparse matrix, the present > version does not return the right answer.
I think there are two parts in the isse. The first one is related to sparse matrix and we don't have an answer yet. The second part is related to compute a partial set of singular values. This is used for example in image compression or to find a matrix with reduce rank that is the closest possible to an input matrix. for this part, we may have an answer. So for the first part, I think WON'T FIX may be an answer (or INCOMPLETE, asking for a patch ...). For the second part, I would suggest to simply postpone to 3.0. Luc > > Dim. > ---------------------------------------------------------------------------- > > Dimitri Pourbaix * > Institut d'Astronomie et d'Astrophysique * Don't worry, be happy > CP 226, office 2.N4.211, building NO * and CARPE DIEM. > Universite Libre de Bruxelles * > Boulevard du Triomphe * Tel : +32-2-650.35.71 > B-1050 Bruxelles * Fax : +32-2-650.42.26 > http://sb9.astro.ulb.ac.be/~pourbaix * mailto:pourb...@astro.ulb.ac.be > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > For additional commands, e-mail: dev-h...@commons.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
