matrix assembling time

[Matthew Knepley]

On Fri, Mar 13, 2009 at 4:39 PM, Ravi Kannan <rxk at cfdrc.com> wrote:

>  Hi Matt
>
> Are you suggesting to use MatGetOrdering()?
>

That is one way.


> Will it work for parallel matrix?
>

It depends on the particular ordering, but I think most do.

  Matt


> Thanks.
>
> Ravi
>
> -----Original Message-----
> *From:* petsc-users-bounces at mcs.anl.gov [mailto:
> petsc-users-bounces at mcs.anl.gov]*On Behalf Of *Matthew Knepley
> *Sent:* Friday, March 13, 2009 11:34 AM
> *To:* PETSc users list
> *Subject:* Re: matrix assembling time
>
> On Fri, Mar 13, 2009 at 12:48 PM, Ravi Kannan <rxk at cfdrc.com> wrote:
>
>> Hi,
>>    This is Ravi Kannan from CFD Research Corporation. One basic question
>> on
>> the ordering of linear solvers in PETSc: If my A matrix (in AX=B) is a
>> sparse matrix and the bandwidth of A (i.e. the distance between non zero
>> elements) is high, does PETSc reorder the matrix/matrix-equations so as to
>> solve more efficiently. If yes, is there any specific command to do the
>> above?
>
>
> You can reorder the matrix using the MatOrdering class.
>
>   Matt
>
>
>>
>> Thanks
>> Ravi
>>
>>
>>
>> -----Original Message-----
>> From: petsc-users-bounces at mcs.anl.gov
>> [mailto:petsc-users-bounces at mcs.anl.gov]On Behalf Of Yixun Liu
>> Sent: Friday, March 06, 2009 12:50 PM
>> To: PETSC
>> Subject: matrix assembling time
>>
>>
>> Hi,
>> Using PETSc the assembling time for a mesh with 6000 vertices  is about
>> 14 second parallelized on 4 processors, but another sequential program
>> based on gmm lib is about 0.6 second. PETSc's solver is much faster than
>> gmm, but I don't know why its assembling is so slow although I have
>> preallocate an enough space for the matrix.
>>
>> MatMPIAIJSetPreallocation(sparseMeshMechanicalStiffnessMatrix, 1000,
>> PETSC_NULL, 1000, PETSC_NULL);
>>
>> Yixun
>>
>>
>>
>
>
> --
> 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
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