Barry wanted to do sth about Plapack. He found some bugs. I don't know details. Of course, if I find some bugs in Petsc, I will report it. I benefit a lot from it. thank you for your work in Petsc :).
Regards, Yujie On Mon, Sep 22, 2008 at 7:29 PM, Matthew Knepley <knepley at gmail.com> wrote: > On Mon, Sep 22, 2008 at 9:43 PM, Lisandro Dalcin <dalcinl at gmail.com> > wrote: > > On Mon, Sep 22, 2008 at 11:03 PM, Yujie <recrusader at gmail.com> wrote: > >> Dear Lisandro: > >> > >> Barry has tried to establish an interface for Plapack. However, there > are > >> some bugs in Plapack. Therefore, it doesn't work. > > > > Sorry, I didn't know about those Plapack issues. > > Neither did I, and seeing as how I use it, this is interesting. Please > please please > report any bugs you find, because I have been using it without problems. > > Matt > > >> I am wondering if CG in > >> Petsc can work with parallel dense matrix. > > > > Of course it works. In fact, any other KSP should work. As Barry said, > > The KSP methods are INDEPENDENT of the matrix format, try -pc_type > > jacobi as preconditioner. > > > >> When using the same matrix, which > >> one is faster, sequential or parallel? thanks. > > > > For a fixed-size matrix, you should get really good speedups iterating > > in parallel. Of course, that would be even better if you can generate > > the local rows of the matrix in each processor. If not, communicating > > the matrix row from the 'master' to the 'slaves' could be a real > > bootleneck (large data to compute at the master while slaves waiting, > > large data to scatter from master to slaves), If you cannot avoid > > dense matrices, then you should try hard to compute the local rows at > > the owning processor. > > > > > >> > >> On Mon, Sep 22, 2008 at 6:51 PM, Lisandro Dalcin <dalcinl at gmail.com> > wrote: > >>> > >>> Well, any iterative solver will actually work, but expect a really > >>> poor scalability :-). I believe (never used dense matrices) that you > >>> could use a direct method (PLAPACK?), but again, be prepared for long > >>> running times if your problem is (even moderately) large. > >>> > >>> On Mon, Sep 22, 2008 at 10:35 PM, Yujie <recrusader at gmail.com> wrote: > >>> > To my knowledge, PETsc doesn't provide parallel dense matrix-based > >>> > solvers, > >>> > such as for CG, GMRES and so on. If it is, how to deal with this > >>> > problem? > >>> > Thanks. > >>> > > >>> > Regards, > >>> > > >>> > Yujie > >>> > > >>> > >>> > >>> > >>> -- > >>> Lisandro Dalc?n > >>> --------------- > >>> Centro Internacional de M?todos Computacionales en Ingenier?a (CIMEC) > >>> Instituto de Desarrollo Tecnol?gico para la Industria Qu?mica (INTEC) > >>> Consejo Nacional de Investigaciones Cient?ficas y T?cnicas (CONICET) > >>> PTLC - G?emes 3450, (3000) Santa Fe, Argentina > >>> Tel/Fax: +54-(0)342-451.1594 > >>> > >> > >> > > > > > > > > -- > > Lisandro Dalc?n > > --------------- > > Centro Internacional de M?todos Computacionales en Ingenier?a (CIMEC) > > Instituto de Desarrollo Tecnol?gico para la Industria Qu?mica (INTEC) > > Consejo Nacional de Investigaciones Cient?ficas y T?cnicas (CONICET) > > PTLC - G?emes 3450, (3000) Santa Fe, Argentina > > Tel/Fax: +54-(0)342-451.1594 > > > > > > > > -- > What most experimenters take for granted before they begin their > experiments is infinitely more interesting than any results to which > their experiments lead. > -- Norbert Wiener > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20080922/cbc228f5/attachment.htm>
