[petsc-users] Roles of ksp_type and pc_type

[Massimiliano Leoni]

In data giovedì 13 novembre 2014 05:59:17, hai scritto:
> On Thu, Nov 13, 2014 at 5:39 AM, Massimiliano Leoni <
> We call Hypre directly to apply P^{-1}.
> 
> It should be. Send -ksp_view and we can verify. 

It looks like that's what's happening! :D
Here it is
http://pastebin.com/6J3Rj4x1

> You should use 
>   -pc_fieldsplit_schur_factorization_type diag
Ok, This is not clear to me.
According to what I studied, Schur decomposition is when I formally eliminate 
a variable [for Stokes, velocity u] and get a system in the others [sole 
pressure], which I then solve by some smart method and substitute back to find 
u. This is done on the full Stokes matrix A, not on the preconditioner...
It should be not what I want to do, as I'm facing the whole system at once.

What does PETSc mean by "Schur" here? 
 
>    Thanks,
> 
>       Matt

Thank you very much!
Massimiliano