[petsc-users] multiply a mpibaij matrix by its block diagonal inverse

[Jed Brown]

"Smith, Barry F." <bsmith at mcs.anl.gov> writes:

>   Hmm, I never had this idea presented to me, I have no way to know if
>   it is particularly good or bad. So essentially you transform the
>   matrix "decoupling the physics alone the diagonal" and then do
>   PCFIELDSPLIT instead of using PCFIELDSPLIT directly on the original
>   equations.

We talked about this several years ago, e.g., in the context of a
low-Mach preconditioner (acting in the pressure space) when using
conservative variables.