[petsc-users] Question on asm

[Jed Brown]

Konstantinos Kontzialis <ckontzialis at lycos.com> writes:

> Dear all,
>
> I am using asm as a preconditioner for solving the Navier Stokes 
> equations. When using ILU as the subdomain preconditioner, I notice 
> convergence problems in the partition boundaries.

I.e., it converges slowly there?  That is natural because the
preconditioner is more accurate in the interior of subdomains.

> This does not happen with the Jacobi preconditioner. 

Naturally, because Jacobi is identical regardless of the partition.

> Do I need to provide any connectivity, node mapping, and/or overlap
> information to Petsc before calling KSPsolve?

No, the matrix is enough.