On Thu, Aug 9, 2012 at 10:19 PM, Yifei Li <yifli82 at gmail.com> wrote:
> > > On Thu, Aug 9, 2012 at 10:59 PM, Matthew Knepley <knepley at gmail.com>wrote: > >> On Thu, Aug 9, 2012 at 9:56 PM, Yifei Li <yifli82 at gmail.com> wrote: >> >>> Matt, >>> >>> I'm new to PETSC, can you pls explain what you mean by 'keep it in >>> unassembled form'? >>> >> >> Just keep two vectors, u^T v, instead of the dense matrix. >> >> > But I need the result of the outer product (e.g, A) for > further calculation (e.g., A*W). > A * W = A * (u v^T) = (A * u) v^T Matt > >> >> Matt >> >> >>> A small example would be nice too. Thanks >>> >>> Yifei >>> >>> On Thu, Aug 9, 2012 at 9:15 PM, Matthew Knepley <knepley at gmail.com>wrote: >>> >>>> On Thu, Aug 9, 2012 at 5:39 PM, Yifei Li <yifli82 at gmail.com> wrote: >>>> >>>>> Hi, >>>>> >>>>> I did not find any function doing this in the manual. Could someone >>>>> suggest a good way to do this? >>>>> >>>> >>>> That gives a dense matrix. You would never want to do this. You would >>>> keep it in unassembled form. >>>> >>>> Matt >>>> >>>> >>>>> >>>>> Thanks >>>>> >>>>> Yifei >>>>> >>>> >>>> >>>> >>>> -- >>>> 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 >>>> >>> >>> >> >> >> -- >> 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 >> > > -- 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/20120809/e2af2395/attachment-0001.html>
