[petsc-users] Conversion between AIJ & BAIJ

[Matthew Knepley]

On Wed, Jan 21, 2015 at 2:29 PM, Chung-Kan Huang <ckhuangf at gmail.com> wrote:

>
> On Wed, Jan 21, 2015 at 2:15 PM, Matthew Knepley <knepley at gmail.com>
> wrote:
>
>> On Wed, Jan 21, 2015 at 2:07 PM, Chung-Kan Huang <ckhuangf at gmail.com>
>> wrote:
>>
>>>
>>> On Wed, Jan 21, 2015 at 2:01 PM, Matthew Knepley <knepley at gmail.com>
>>> wrote:
>>>
>>>> On Wed, Jan 21, 2015 at 1:55 PM, Chung-Kan Huang <ckhuangf at gmail.com>
>>>> wrote:
>>>>
>>>>>
>>>>> On Wed, Jan 21, 2015 at 1:44 PM, Matthew Knepley <knepley at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> On Wed, Jan 21, 2015 at 1:40 PM, Chung-Kan Huang <ckhuangf at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> Then A & AB are not longer the same matrix.  They become complete
>>>>>>> two individuals aren't they?
>>>>>>> If I do whatever to AB after AB is created the A is still the same
>>>>>>> old A and not going to be affected by the operations I do to AB.
>>>>>>>
>>>>>>
>>>>>> Yes.
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> What I am really looking for is a way to create two interfaces (one
>>>>>>> as AIJ and one as BAIJ) but they both refer to the same matrix.
>>>>>>>
>>>>>>
>>>>>> Why would you ever want this? Why not just using BAIJ?
>>>>>>
>>>>> As I mentioned in the beginning.  There are parts of the code gets
>>>>> benifit when AIJ is used and the other part gets benifit  if BAIJ is used.
>>>>>
>>>>> For instance,
>>>>>
>>>>> I'd like to use MatSetValuesBlocked but I also want to use ilu
>>>>> constructed by AIJ instead of BAIJ (our experience found ilu from BAIJ
>>>>> behaves funny sometimes.
>>>>>
>>>>
>>>> If the blocks truly are dense, then ILU(0) is identical on both.
>>>>
>>>
>>> Unfortunately the life is not that easy.  The blocks are spares and we
>>> found ILU(1) works better for our case.
>>> And besides that is not the only reason I want to have AIJ & BAIJ
>>> interfaces, we have some code management issue and I am looking for short
>>> cut to unite them.
>>>
>>> So go back to the original question the short answer is no way?
>>>
>>
>> Yes, it would not make sense.
>>
>> What problem are you using ILU(1) for?
>>
>
> I am using it for flow simulation for reservoir problems.
>

Have you considered trying algebraic multigrid?


> Some issues we found is that
> 1) for a * x = 0 it doesn't return x = 0
>

This is impossible. There must be a bug in the code.

  Thanks,

     Matt


> 2) After compared ILU(1) with BAIJ against with ILU(1) with AIJ I found
> latter one is better.  I could not find anything wrong with my BAIJ version
> though.  However, experiences suggested that BAIJ's ILU(1) should be better.
>
>
> Thanks,
>
> Kan
>
>>
>>   Thanks,
>>
>>      Matt
>>
>>
>>> Thanks,
>>>
>>> Kan
>>>
>>>>
>>>>   Matt
>>>>
>>>>
>>>>> Thanks,
>>>>>
>>>>> Kan
>>>>>
>>>>>>
>>>>>>   Thanks,
>>>>>>
>>>>>>       Matt
>>>>>>
>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> Kan
>>>>>>> On Wed, Jan 21, 2015 at 1:20 PM, Matthew Knepley <knepley at gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> On Wed, Jan 21, 2015 at 12:56 PM, Chung-Kan Huang <
>>>>>>>> ckhuangf at gmail.com> wrote:
>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> So if I do
>>>>>>>>>
>>>>>>>>> Mat A, AB;
>>>>>>>>> MatCreateAIJ(comm,m,n,M,N,d_nz, d_nnz,o_nz, o_nnz, &A);
>>>>>>>>> MatConvert(A, MATBAIJ, MAT_INITAL_MATRIX, &AB);
>>>>>>>>> MatSetBlockSize(AB, bs)
>>>>>>>>> I can create AB as a BAIJ with block size of bs from A which is a
>>>>>>>>> AIJ matrix.
>>>>>>>>>
>>>>>>>>> So from this point I can use both A and AB and they will mean the
>>>>>>>>> same matrix. Am I right?
>>>>>>>>>
>>>>>>>>
>>>>>>>> Yes
>>>>>>>>
>>>>>>>>
>>>>>>>>> At the end of the program do I only destory one of them or both?
>>>>>>>>>
>>>>>>>>
>>>>>>>> Both
>>>>>>>>
>>>>>>>>
>>>>>>>>> Do I need to worry about anything in terms of memory penalty?
>>>>>>>>>
>>>>>>>>
>>>>>>>> It is twice the memory. Its another matrix.
>>>>>>>>
>>>>>>>> Did you catch when Jed said you could jsut create the BAIJ up front?
>>>>>>>>
>>>>>>>>   Thanks,
>>>>>>>>
>>>>>>>>     Matt
>>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Thanks,
>>>>>>>>>
>>>>>>>>> Kan
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Tue, Jan 20, 2015 at 4:39 PM, Barry Smith <bsmith at mcs.anl.gov>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>   You can do a MatConvert() (requires another copy of the matrix)
>>>>>>>>>> for the parts that benefit from BAIJ.
>>>>>>>>>>
>>>>>>>>>>   Barry
>>>>>>>>>>
>>>>>>>>>> > On Jan 20, 2015, at 4:33 PM, Chung-Kan Huang <
>>>>>>>>>> ckhuangf at gmail.com> wrote:
>>>>>>>>>> >
>>>>>>>>>> > Hi,
>>>>>>>>>> >
>>>>>>>>>> > Does PETSc provide means for conversion between AIJ & BAIJ.
>>>>>>>>>> >
>>>>>>>>>> > My matrix is created as AIJ because it makes life easy for most
>>>>>>>>>> part of the applications but some part of applications actually get some
>>>>>>>>>> benefits with BAIJ.  So I wonder if a matrix can exist as two idenfities
>>>>>>>>>> and I can use either format depend on which one is more convenient at run
>>>>>>>>>> time.
>>>>>>>>>> >
>>>>>>>>>> > So in my case the block size is fixed and identical for all
>>>>>>>>>> blocks.
>>>>>>>>>> >
>>>>>>>>>> >
>>>>>>>>>> > Thanks,
>>>>>>>>>> >
>>>>>>>>>> >
>>>>>>>>>> > Kan
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>>
>>>>>>>>> *Cheers*
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> 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
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>>
>>>>>>> *Cheers*
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> 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
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> *Cheers*
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> 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
>>>>
>>>
>>>
>>>
>>> --
>>>
>>> *Cheers*
>>>
>>
>>
>>
>> --
>> 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
>>
>
>
>
> --
>
> *Cheers*
>



-- 
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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