[petsc-users] ASM Interface (Additive Schwarz Method)

Mark Adams mfadams at lbl.gov
Fri Jan 18 07:42:19 CST 2019


>
>
>
> This works perfectly as long as I use PC_ASM_BASIC for the PCASMType. If I
> switch to PC_ASM_RESTRICT, my GMRES algorithm, does not converge anymore.
> Why is this?
>

PC_ASM_RESTRICT specifies the use of a different algorithm. It is a cheaper
algorithm in terms of work (communication) but is weaker mathematically, in
parallel.


> Am I misunderstanding the ASM interface? (i.e. is the way I define the
> overlap
> wrong?)
> Do I have to somehow permute the right-hand side of system of equations?
>
> It’s probably important to know, that PCSide is set to PC_RIGHT.
>
> Thank you for your help!
> With best regards,
> Nils
>
> P.S.: I very much hope, that my small picture is not destroyed by our
> email clients.
>
>
> --
> M.Sc. Nils Schween
> Research Associate
>
> Phone: +49 6221 54 14512
> Mail: nils.schween at uni-heidelberg.de
>
> Heidelberg University
> Engineering Mathematics and Computing Lab (EMCL)
> Interdisciplinary Center for Scientific Computing (IWR)
> Im Neuenheimer Feld 205, D-69120 Heidelberg
> http://emcl.iwr.uni-heidelberg.de
>
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