[petsc-users] How to reorder the local part of the parallel mat?

[Jed Brown]

http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatGetDiagonalBlock.html


On Wed, Jan 16, 2013 at 3:51 PM, Fande Kong <fd.kong at siat.ac.cn> wrote:

> Thanks, Jed,
>
> Could I directly extract a local sub matrix from the parallel matrix? The
> local part should be a sequential matrix.
>
>
> On Wed, Jan 16, 2013 at 2:32 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
>
>> 1. Partition the mesh
>> 2. Create a sequential matrix representing local mesh adjacency
>> 3. Use MATORDERINGRCM to get a new ordering for that sequential matrix
>> 4. Broadcast the new global indices to neighbors
>>
>>
>> On Wed, Jan 16, 2013 at 2:26 PM, Fande Kong <fd.kong at siat.ac.cn> wrote:
>>
>>> Barry, Thank you very much.
>>>
>>> What I want to do is to order the original mesh.  I have partitioned the
>>> mesh. But I want to reorder the vertices. Thus I create a matrix that
>>> represent the relationships of the vertices, and then I want to use the
>>> ordering methods in petsc to reorder the vertices by using matgetordering.
>>>
>>> What should I do if I want to use the ordering methods
>>> (e.g. MATORDERINGRCM ) in petsc to reorder the mesh vertices?
>>>
>>> On Wed, Jan 16, 2013 at 1:10 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>>>
>>>>
>>>> On Jan 16, 2013, at 1:53 PM, Fande Kong <fd.kong at siat.ac.cn> wrote:
>>>>
>>>> > Hi all,
>>>> >
>>>> > I create a parallel mat with type MATMPIAIJ, and use the
>>>> MatGetOrdering to reorder it. But it doesn't work. Who can tell me how to
>>>> do that? I just want to reorder the local part of the matrix.
>>>>
>>>>    We don't have code in place for this type of thing. Maybe if you
>>>> explain why you would like it we could suggest alternatives.
>>>>
>>>>     Generally we recommend ordering the original mesh appropriately so
>>>> that the resulting matrices have good orderings and don't recommend
>>>> reordering the matrices directly (except for direct solvers).
>>>>
>>>>    Barry
>>>>
>>>> >
>>>> > Thanks,
>>>> >
>>>> > --
>>>> > Fande Kong
>>>> > ShenZhen Institutes of Advanced Technology
>>>> > Chinese Academy of Sciences
>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> Fande Kong
>>> ShenZhen Institutes of Advanced Technology
>>> Chinese Academy of Sciences
>>>
>>
>>
>
>
> --
> Fande Kong
> ShenZhen Institutes of Advanced Technology
> Chinese Academy of Sciences
>
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