[petsc-users] Regarding ksp ex42 - Citations

[domenico lahaye]

Thank you for sharing the additional insight.
The separate Galerkin coarsening of A and M will be part of the overall algorithm only. 

I think it is wise to implement in two stages: first a fragile implementation and later 
a more stable one. 

Kind wishes, Domenico. 
 
      From: Lawrence Mitchell <lawrence.mitchell at imperial.ac.uk>
 To: domenico lahaye <domenico_lahaye at yahoo.com> 
Cc: PETSc Users List <petsc-users at mcs.anl.gov>
 Sent: Thursday, July 21, 2016 1:09 PM
 Subject: Re: [petsc-users] Regarding ksp ex42 - Citations
   

> On 21 Jul 2016, at 10:55, domenico lahaye <domenico_lahaye at yahoo.com> wrote:
> 
> Apologies for being not sufficient clear in my previous message.
> 
> I would like to be able to Galerkin coarsen A^h to obtain A^H
> and to separately Galerkin coarsen M^h to obtain M^H.
> 
> So, yes, the way in which I currently (partially) understand your
> description of the new DMCreateMatrices would do the job.

If you want to separately coarsen A and M via Galerkin, I think it will be easier to just change the code in PCSetUp_MG to handle the case where A and M are different on the coarse levels.  Effectively you just need to replicate the code that computes the coarse grid "B" matrix to separately compute coarse grid A and B matrices and pass them in to KSPSetOperators.

Cheers,

Lawrence


  
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