[petsc-users] Assembly of local Mat's to a parallel Mat

[Hui Zhang]

On Apr 12, 2013, at 4:55 PM, Matthew Knepley wrote:

> On Fri, Apr 12, 2013 at 9:44 AM, Hui Zhang <mike.hui.zhang at hotmail.com> wrote:
> Assembly of local Mat's to a parallel Mat formally defined by A = \sum_i Ri^T Ai Ri.
> 
> My Ai's are originally defined in sub-communicators.  In Petsc, I was told before there are no counterpart of Ri that can promote the mat Ai to sup-communicator where A stays. (VecScatter can only acts on Vec but not Mat)
> 
> So, what is the easiest way to achieve this task?  Note that Ai's are already defined in sub-communicators.
> 
> What are you trying to do? Get the action of A, or assemble it directly?

Assembly it directly. I just found MatGetSubMatricesParallel.  Maybe I can learn from the source codes of this function but I can not find where they are.

> 
>    Matt
> 
> -- 
> 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