[petsc-users] AOCreateBasic & AOCreateBasicIS

[Jed Brown]

Hui Zhang <mike.hui.zhang at hotmail.com> writes:

> Thanks! Is the problem you mentioned serious when the indices to be
> translated on each processor include only a few ones beyond the input
> myapp[] of AOCreateBasic?  Because I only use AO for FEM assembly so I
> would not translate too many beyond local ranges.

Don't use AO for FEM assembly.  Use a local-to-global mapping and
MatSetValuesLocal().  That is memory scalable and simpler code.

> Another question: do the inputs IS's to AOCreateBasicIS include all
> the indices, and AOCreateBasicIS would not do any gathering of
> indices?

You could create an AO on PETSC_COMM_SELF, but I don't think you should
use AO.