[petsc-users] Variable Block Row format in PETSc

[Longxiang Chen]

VBR like in this link, use 6 arrays to represent a matrix.
http://docs.oracle.com/cd/E19061-01/hpc.cluster5/817-0086-10/prog-sparse-support.html

Each row is a vertex in the graph, , and use parmetis to partition the
graph to minimize the number of cuts between different processors. (reduce
communication when calculate Matrix-Vector)
The matrix is calculated from Jacobian and construct the A and b from the
result of Jacobian (in VBR).


Best regards,
Longxiang Chen

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On Tue, May 14, 2013 at 2:51 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> What kind of VBR matrix? What are you partitioning using parmetis? A mesh?
> The blocks of the matrix? How do you create the entries in the matrix?
> On May 14, 2013 4:36 PM, "Longxiang Chen" <suifengls at gmail.com> wrote:
>
>> To whom it may concern,
>>
>> I use parmetis to partition a mesh for a sparse matrix.
>> Then I distribute the data to the  appropriate processors according to
>> the result of partition.
>>
>> The sparse matrix is stored in Variable Block Row(VBR) format.
>> After the distribution, I want to call PETSc KSP solver to solve Ax = b.
>> I tried to convert VBR to AIJ or CSR format, but the data would be
>> re-distributed.
>>
>> The ideal method is to keep the distribution result from parmetis.
>> For example, after parmetis, processor 0 has 0, 1, 4, and processor 1
>> has 2, 3, 5. I wish the PETSc would not change this distribution and
>> solve Ax = b.
>>
>> Are there any approaches to call KSP solver in VBR format from PETSc?
>> Or any suggestions for solving Ax = b?
>>
>> Thanks in advance.
>>
>> Regards,
>> Longxiang Chen
>>
>>
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