[petsc-users] Conversion between AIJ & BAIJ

Chung-Kan Huang ckhuangf at gmail.com
Wed Jan 21 15:16:40 CST 2015 

On Wed, Jan 21, 2015 at 2:36 PM, Matthew Knepley <knepley at gmail.com> wrote:

> 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?
>

I am solving PDE fully implicitly and as far as I know algebraic multigrid
only good for pressure equations
I will need 2 stages PC while AMG is for pressure stage but I will still
need something like ILU for second stage.



>
>
>> 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
>



-- 

*Cheers*
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