[petsc-users] Solving Poisson equation with multigrid

[Michele Rosso]

So should I always use an odd number of grid points?
There is no way around this?

Michele

On 05/17/2013 03:53 PM, Jed Brown wrote:
> Michele Rosso <mrosso at uci.edu> writes:
>
>> I added KSPSetDM() and now the error I receive is:
>>
>> [0]PETSC ERROR: --------------------- Error Message
>> ------------------------------------
>> [0]PETSC ERROR: No support for this operation for this object type!
>> [0]PETSC ERROR: For coloring efficiency ensure number of grid points in
>> X is divisible
>>                    by 2*stencil_width + 1
>> !
>> [0]PETSC ERROR:
>> ------------------------------------------------------------------------
>> [0]PETSC ERROR: Petsc Release Version 3.3.0, Patch 3, Wed Aug 29
>> 11:26:24 CDT 2012
>> [0]PETSC ERROR: See docs/changes/index.html for recent updates.
>> [0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
>> [0]PETSC ERROR: See docs/index.html for manual pages.
>> [0]PETSC ERROR:
>> ------------------------------------------------------------------------
>> [0]PETSC ERROR: ./hit on a  named nid25119 by Unknown Fri May 17
>> 17:41:05 2013
>> [0]PETSC ERROR: Libraries linked from
>> [0]PETSC ERROR: Configure run at
>> [0]PETSC ERROR: Configure options
>> [0]PETSC ERROR:
>> ------------------------------------------------------------------------
>> [0]PETSC ERROR: DMCreateColoring_DA_3d_MPIAIJ() line 288 in
>> src/dm/impls/da/fdda.c
>> [0]PETSC ERROR: DMCreateColoring_DA() line 172 in src/dm/impls/da/fdda.c
>> [0]PETSC ERROR: DMCreateColoring() line 709 in src/dm/interface/dm.c
>> [0]PETSC ERROR: DMComputeJacobian() line 2206 in src/dm/interface/dm.c
>> [0]PETSC ERROR: KSPSetUp() line 228 in src/ksp/ksp/interface/itfunc.c
>>
>>
>> My 3D grid is composed by 256^3 nodes, I am using 4 processors and the
>> the DMDA is initialized as:
> Yes, with a vertex-centered discretization, use 257^3 instead.
>

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