[petsc-users] (Fast?) assembly of upper triangle and MatZeroRows

[Barry Smith]

On Aug 8, 2011, at 2:37 PM, Jed Brown wrote:

> On Mon, Aug 8, 2011 at 14:23, Barry Smith <bsmith at mcs.anl.gov> wrote:
> We have a MatZeroRowsColumns() for MPIAIJ and SeqSBAIJ, what about having one for MPISBAIJ?
> 
> Of course this makes sense to have, but I don't think it solves the problem. How do you solve more than one system?

   You don't 

> How would you use this interface with SNES?

   The user calls this as part  the FormJacobian()  (in the same way as if they explicitly remove those rows and columns (what Matt likes) in the matrix assembly.


  Barry