[petsc-users] SOLVE + PC combination for 7 point stencil (unstructured) poisson solution

[Matthew Knepley]

On Mon, Jun 26, 2023 at 12:08 PM Vanella, Marcos (Fed) via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Than you Matt and Mark, I'll try your suggestions. To configure with hypre
> can I just use the --download-hypre configure line?
>

Yes,

  Thanks,

    Matt


> That is what I did with suitesparse, very nice.
> ------------------------------
> *From:* Mark Adams <mfadams at lbl.gov>
> *Sent:* Monday, June 26, 2023 12:05 PM
> *To:* Vanella, Marcos (Fed) <marcos.vanella at nist.gov>
> *Cc:* petsc-users at mcs.anl.gov <petsc-users at mcs.anl.gov>
> *Subject:* Re: [petsc-users] SOLVE + PC combination for 7 point stencil
> (unstructured) poisson solution
>
> I'm not sure what MG is doing with an "unstructured" problem. I assume you
> are not using DMDA.
> -pc_type gamg should work
> I would configure with hypre and try that also: -pc_type hypre
>
> As Matt said MG should be faster. How many iterations was it taking?
> Try a 100^3 and check that the iteration count does not change much, if at
> all.
>
> Mark
>
>
> On Mon, Jun 26, 2023 at 11:35 AM Vanella, Marcos (Fed) via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
>
> Hi, I was wondering if anyone has experience on what combinations are more
> efficient to solve a Poisson problem derived from a 7 point stencil on a
> single mesh (serial).
> I've been doing some tests of multigrid and cholesky on a 50^3 mesh. *-pc_type
> mg* takes about 75% more time than *-pc_type cholesky
> -pc_factor_mat_solver_type cholmod* for the case I'm testing.
> I'm new to PETSc so any suggestions are most welcome and appreciated,
> Marcos
>
>

-- 
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

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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