[petsc-users] ksppreonly question

[Shao-Ching Huang]

On Fri, Sep 21, 2012 at 3:15 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> Like which part? Lower and upper triangular in some ordering? That's exactly
> what PCSOR does.
>

In this particular finite volume discretization, the flux normal to a
face involves the cell-center values on each side of the face (1),
plus values from neighboring nodes (2) [due to non-orthogonal mesh
cell shape]. The A1 part include coefficients from (1). A2 includes
those in (2).