[petsc-users] shell preconditioner for Schur complement

[Matteo Semplice]

Il 11/02/21 06:41, Barry Smith ha scritto:
>    Best to just look at the code to see exactly what it is doing: src/ksp/pc/impls/fieldsplit/fieldsplit.c  function PCApply_FieldSplit_Schur()
>
>    There is no particular "scaling" applied to the vectors. It might be easiest to track through the computational process with the debugger (you can call VecView(v,0) in the debugger anytime to see the current vector) to see why the "scaling" seems to change.
>
>    Barry

Found!

It came from the initial rescaling b->b/norm(b) in the fgmres for the 
entire matrix.

We are now set and we can concentrate on our routine.

Thanks a lot Matthew and Barry!

Matteo & Elena

-- 
Prof. Matteo Semplice
Università degli Studi dell’Insubria
Dipartimento di Scienza e Alta Tecnologia – DiSAT
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