[petsc-users] Regarding ksp ex42 - Citations

Mon Jul 18 02:11:48 CDT 2016

On Mon, Jul 18, 2016 at 1:41 AM, domenico lahaye <domenico_lahaye at yahoo.com>
wrote:

> Dear Matthew,
>
>   I would like to place the FormJacobian statement in ex25.c in such a way
> that I can view
> the result on the different levels. Can you please point me to an example?
>

You can use options to do this. For any KSP solve, you can use

  -ksp_view_mat draw

for whatever viewer you want. In the mg cycle, you can use

  -mg_level_2_ksp_view_mat draw

or for all levels

  -mg_levels_ksp_view_mat draw

  I would like to do above with Galerkin coarsening as well. So yes, I do
> expect that I will need the
> hooks attached to the different MG levels. I appreciate more pointers here
> as well.
>

The above should work with either method.

  Thanks,

    Matt

>    Thanks, Domenico.
>
>
> *From:* Matthew Knepley <knepley at gmail.com>
>
>
> *To:* domenico lahaye <domenico_lahaye at yahoo.com>
> *Cc:* PETSc Users List <petsc-users at mcs.anl.gov>
> *Sent:* Monday, July 18, 2016 8:16 AM
>
> *Subject:* Re: [petsc-users] Regarding ksp ex42 - Citations
>
> On Mon, Jul 18, 2016 at 12:59 AM, domenico lahaye <
> domenico_lahaye at yahoo.com> wrote:
>
> Thanks for all the pointers.
>
> I am happy to switch to ksp/examples/tutorials/ex25.c in a first instance
> as you suggest.
>
>     I am still stuck with the same issue as before though. I am trying to
> extract the hierarchy
>     of coarser grid matrices and the intergrid transfer operators from the
> DMDA data structure. I would
>     like to modify these operators and define a multigrid cycle with the
> modified operators.
>
>     Given A^h (Helmholtz) and M^h (shifted Laplace), I would like to
> define a multigrid cycle involving
>     both A^H and M^H. Can I rely on the multilevel DMDA structure to
> construct A^H and M^H for me
>     in a set-up phase, plug them into a user-defined context, and plug
> them back out in a solve phase?
>
>
> If you are not using -pc_mg_galerkin, then the FormJacobian is called
> separately on each level to rediscretize the operator.
> The only thing that changes is the DMDA that is passed to the call. If you
> need more information, there are hooks to
> attach different contexts to each MG level. Do you need this?
>
>   Thanks,
>
>      Matt
>
>
> Thanks, Domenico.
>
>
> ------------------------------
> *From:* Matthew Knepley <knepley at gmail.com>
> *To:* Barry Smith <bsmith at mcs.anl.gov>
> *Cc:* domenico lahaye <domenico_lahaye at yahoo.com>; "
> petsc-users at mcs.anl.gov" <petsc-users at mcs.anl.gov>
> *Sent:* Sunday, July 17, 2016 2:29 PM
> *Subject:* Re: [petsc-users] Regarding ksp ex42 - Citations
>
> On Sat, Jul 16, 2016 at 10:11 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>
> > On Jul 14, 2016, at 12:21 PM, domenico lahaye <domenico_lahaye at yahoo.com>
> wrote:
> >
> > Dear PETSc team,
> >
> > 1) I am looking into ks/examples/tutorials/ex42.c I am still new to the
> DMDA structure
> >     and likely not giving it as much time as it deserves. However, I do
> not see immediately
> >     what function is responsible for calling PCMGSetSmoother and
> PCMGSetResidual.
> >
> >      I tried to call PCMGGetCoarseSolve(pc, &kcpc) and subsequently
> >      KSPGetOperators (kspc, ... ) to check how the coarse grid operator
> is defined
> >      after calling DMCoarsenHierarchy, but that failed.
> >
> >      I am solving Helmholtz with shifted Laplace, and managed to exploit
> DMDA to perform
> >      a multigrid solve on the preconditioner. In a next stage I want to
> implement the deflation
> >      using DMDA as well.
> >
> > 2) On http://www.mcs.anl.gov/petsc/documentation/referencing.html I see
> >
> > @Misc{petsc-web-page,
> >             author = {Satish Balay and Shrirang Abhyankar and Mark~F.
> Adams and Jed Brown and Peter Brune
> >                       and Kris Buschelman and Lisandro Dalcin and Victor
> Eijkhout and William~D. Gropp
> >                       and Dinesh Kaushik and Matthew~G. Knepley
> >                       and Lois Curfman McInnes and Karl Rupp and
> Barry~F. Smith
> >                       and Stefano Zampini and Hong Zhang and Hong Zhang},
> >             title =  {{PETS}c {W}eb page},
> >             url =    {http://www.mcs.anl.gov/petsc},
> >             howpublished = {\url{http://www.mcs.anl.gov/petsc}},
> >             year = {2016}
> >           }
> >
> >
> >
> > Is the last author mentioned twice intentionally?
> >
> > 3) On
> http://www.mcs.anl.gov/petsc/publications/petscapps-bib.html#OpenFOAM%202.2.1
> I see
> >
> > @misc{OpenFOAM
> > ,
> >
> >
> > title =       "OpenFOAM",
> >
> > howpublished  =       "\url{http://www.openfoam.com}",
> >
> > url   =       {http://www.openfoam.com},
> >
> > note  =       "OpenFOAM is a free, open source CFD software package. It
> allows PETSc linear algebra and solvers to be used underneath.",
> >
> > key   =       "OpenFOAM 2.2.1"
> >
> > }
> >
> >
> > Do you have more information on the use of PETSc within OpenFoam?
>
>   Very good question. It seems that this citation is wrong or no longer
> valid; I have removed it from the PETSc repository. I could find no mention
> of PETSc usage in the OpenFoam and its third party packages. I think we
> should not have been listing this citation.
>
>
> This suggests that people are using it with OpenFOAM:
> http://powerlab.fsb.hr/ped/kturbo/OpenFOAM/slides/PatersonNuTTS2009.pdf
>
> In fact, they use PETSc in the dynamic overset grid implementation for
> OpenFOAM, which I think is an approved extension:
>
>
> http://web.student.chalmers.se/groups/ofw5/Abstracts/DavidBogerAbstractOFW5.pdf
>
>      Matt
>
>
>
>    Barry
>
> >
> > 4) @matt in response to a question he raised in Vienna
> >
> > MIPSE is a BEM solver. Details are on:
> >
> http://www.g2elab.grenoble-inp.fr/plateforms/mipse-modeling-of-interconnected-power-systems-632862.kjsp?RH=G2ELAB_R-MAGE
> >
> > Cheers, Domenico Lahaye.
>
> >
>
>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
>
>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
>
>

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20160718/22c519ff/attachment-0001.html>