To owned DOF. Any ghosting of the problem is not relevant since the null space created is purely a linear algebra thing that is related to the global vector (not local vectors).
Barry > On Dec 4, 2023, at 9:44 AM, Jordi Manyer Fuertes via petsc-users > <[email protected]> wrote: > > Dear PETSc users/developpers, > > I am currently trying to use the method `MatNullSpaceCreateRigidBody` > together with `PCGAMG` to efficiently precondition an elasticity solver in > 2D/3D. > > I have managed to make it work in serial (or with 1 MPI rank) with > h-independent number of iterations (which is great), but the solver diverges > in parallel. > > I assume it has to do with the coordinate vector I am building the null-space > with not being correctly setup. The documentation is not that clear on which > nodes exactly have to be set in each partition. Does it require nodes > corresponding to owned dofs, or all dofs in each partition (owned+ghost)? > What ghost layout should the `Vec` have? > > Any other tips about what I might be doing wrong? > > Thanks, > > Jordi >
