[petsc-users] Ghosted vectors in KSP via SNES

[Jed Brown]

On Wed, Mar 30, 2011 at 18:43, I-Kamenetskiy, Dmitry S <
dmitry.s.kamenetskiy at boeing.com> wrote:

> I have run in to the following issue with the PETSc SNES usage. The logic
> of the SNESSolve() routine in my code is that the solution vector x should
> include ghost points at the boundary of subdomains in the distributed case.


Not true, the solvers take "global" vectors, each degree of freedom appears
exactly once on exactly one process. Ghost points are typically needed
inside of residual evaluation and Jacobian assembly, but they should not be
present in the vector you give to the solver.
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