[petsc-users] PCs and MATIS

[Eric Chamberland]

Hi Pierre,

ok, that's a nice trick!

Thanks for this great hint! :)

Eric


On 2021-12-14 3:58 p.m., Pierre Jolivet wrote:
> Hello Eric,
> Why do you want to use a MATIS?
> This solution that Barry suggested to me some time ago is perfectly 
> functioning: 
> https://lists.mcs.anl.gov/pipermail/petsc-dev/2020-January/025491.html 
> <https://lists.mcs.anl.gov/pipermail/petsc-dev/2020-January/025491.html>
> That’s what I do for optimized (restricted) additive Schwarz.
> You can see also how to use this “trick” from Barry here: 
> https://gitlab.com/petsc/petsc/-/commit/ba409789b0c94205af794ad85bdac232504f2b3f#2c7d367ac831f3b0c5fb767c0eb16c1ea7ae7fe0_821_821 
> <https://gitlab.com/petsc/petsc/-/commit/ba409789b0c94205af794ad85bdac232504f2b3f#2c7d367ac831f3b0c5fb767c0eb16c1ea7ae7fe0_821_821> (it’s 
> in a WIP branch, and for the fine-level PCASM smoother used in 
> PCHPDDM, but at least it’s actual code, in case you do not follow what 
> Barry and I are saying in the old thread).
>
> Thanks,
> Pierre
>
>> On 14 Dec 2021, at 9:37 PM, Eric Chamberland 
>> <Eric.Chamberland at giref.ulaval.ca 
>> <mailto:Eric.Chamberland at giref.ulaval.ca>> wrote:
>>
>> Hi,
>>
>> We want to use an Additive Schwarz preconditioner (like PCASM) 
>> combined with overlapping meshes *and* specific boundary conditions 
>> to local (MATIS) matrices.
>>
>> At first sight, MATIS is only supported for BDDC and FETI-DP and is 
>> not working with PCASM.
>>
>> Do we have to write a new PC from scratch to combine the use of mesh 
>> overlap, MATIS and customized local matrices?
>>
>> ...or is there any working example we should look at to start from? :)
>>
>> Thanks a lot!
>>
>> Eric
>>
>> -- 
>> Eric Chamberland, ing., M. Ing
>> Professionnel de recherche
>> GIREF/Université Laval
>> (418) 656-2131 poste 41 22 42
>>
>
-- 
Eric Chamberland, ing., M. Ing
Professionnel de recherche
GIREF/Université Laval
(418) 656-2131 poste 41 22 42

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