Likely it would be better; it should not be worse. Barry
On Sep 22, 2008, at 4:44 PM, Aron Ahmadia wrote: > Wouldn't it be better in this case to use an MPIScatterV? > > ~A > > On Mon, Sep 22, 2008 at 4:03 PM, Barry Smith <bsmith at mcs.anl.gov> > wrote: > > I would only expect good performance if you used MPI calls to send > the blocks of rows of the matrix to the process > they belong to and use MatGetArray() to pass into the MPI_Recv to > receive the data into. > > Barry > > > On Sep 22, 2008, at 1:34 PM, Yujie wrote: > > Thank you for your reply, Matt. I have checked the tutorials. They > just use specified values and MatSetValues() to make a parallel > matrix. Now, the matrix I use is in a single node of the cluster. I > have 'M' nodes in this cluster. I need to copy the sequential matrix > to other 'M-1' nodes and then use MatSetValues() or I just use > MatSetvalues() in the node where the matrix is? The latter should > work, right? thanks. > > Yujie > > > On Mon, Sep 22, 2008 at 11:09 AM, Matthew Knepley > <knepley at gmail.com> wrote: > The right way to do this is to input the matrix using MatSetValues() > in a distribute fashion. You can consult any of the tutorials, for > instance > KSP ex2 for an example of this. > > Matt > > On Mon, Sep 22, 2008 at 12:57 PM, Yujie <recrusader at gmail.com> wrote: > > Hi, Petsc developer > > > > Now, I have a sequential dense matrix. How to get a parallel > matrix based on > > it? thanks a lot. > > > > Regards, > > > > Yujie > -- > 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 > > > >
