On Apr 25, 2012, at 3:48 PM, Barry Smith wrote:
>
> On Apr 25, 2012, at 2:44 PM, Mark F. Adams wrote:
>
>>
>> On Apr 25, 2012, at 12:22 PM, Hong Zhang wrote:
>>
>>> Mark,
>>>
>>> I attach it with this code:
>>>
>>> /* attach block size of columns */
>>> if( pc_gamg->col_bs_id == -1 ) {
>>> ierr = PetscObjectComposedDataRegister( &pc_gamg->col_bs_id );
>>> assert(pc_gamg->col_bs_id != -1 );
>>> }
>>> ierr = PetscObjectComposedDataSetInt( (PetscObject)Prol,
>>> pc_gamg->col_bs_id, data_cols ); CHKERRQ(ierr);
>>>
>>> which Hong can not see w/o my ID. so we need a mechanism for me to get
>>> this to PtAP.
>>>
>>> Sorry, I do not understand what do you mean here.
>>> Do you want add above into the implementation of PtAP or petsc?
>>
>> This is an architectural/API decision. I will do what you and Barry want.
>> You could add a parameter to PtAP, or add a field to Mat (column block
>> size), or whatever.
>
> Mark,
>
> I'm leaning towards setting a column block size, MatSetColumnBlockSize().
> But what exactly is a "column block size"? Is it really a column blocksize
> in the sense that nbs columns next to each other always have the exact same
> nonzero pattern: for example
>
> xx 00 xx 00
> yy 00 yy 00
> zz 00 zz 00
No. The blocks are dense for smoothed aggregation but for geometric MG and
classical AMG the blocks are scaled identity.
>
> or is it a more vague thing that defined by "well if you compute Pt A P the
> result has a blocksize of nbs". In that case we would provide a
> MatSetVirtualColumnBlockSize()
>
All I really need is for the coarse grid matrix to have the block size, because
that is used to create a graph (for "vertices" not equations). The method that
constructs the prolongator knows the block size, so I attach it to P. I could
actually attach the block size to the coarse matrix in the way that I do with
P, or pass it around as a parameter internally, I suppose.
Mark
> Thanks
>
> Barry
>
>>
>> Mark
>>
>>> Hong
>>>
>>> And MatGetSubMatrix has to inherit block size, which I assume is trial.
>>>
>>> Mark
>>>
>>> On Apr 24, 2012, at 11:14 PM, Barry Smith wrote:
>>>
>>>>
>>>> On Apr 24, 2012, at 8:14 PM, Mark F. Adams wrote:
>>>>
>>>>>
>>>>> On Apr 24, 2012, at 5:01 PM, Barry Smith wrote:
>>>>>
>>>>>>
>>>>>> On Apr 24, 2012, at 2:38 PM, Mark F. Adams wrote:
>>>>>>
>>>>>>>
>>>>>>> On Apr 24, 2012, at 3:28 PM, Hong Zhang wrote:
>>>>>>>
>>>>>>>> Mark :
>>>>>>>> Shall C=PtAP inherit the block size of A?
>>>>>>>> Currently, MatPtAP() is only implemented with aij bs=1.
>>>>>>>
>>>>>>> No, as I said, algebraically it should inherit the column block size of
>>>>>>> P, but that is not available.
>>>>>>
>>>>>> What is the column block size of P and how do you know what it is?
>>>>>
>>>>> I now attach it to the P matrix instead of adding it as a return
>>>>> parameter of the create P method. So I keep track of it in the code.
>>>>> Its size is the number of null space vectors.
>>>>
>>>> Ok if P knows its block size then the code that computes PtAP can set the
>>>> block size of the resulting matrix as it creates it using the information
>>>> in P. So is the issue on calling MatSetBlockSize() now resolved and
>>>> everyone happy?
>>>>
>>>> Barry
>>>>
>>>>>
>>>>> Mark
>>>>>
>>>>>>
>>>>>> Barry
>>>>>>
>>>>>>>
>>>>>>> Perhaps PtAP should take a parameter for the block size ...
>>>>>>>
>>>>>>> Mark
>>>>>>>
>>>>>>>> Hong
>>>>>>>>
>>>>>>>> On Apr 24, 2012, at 2:55 PM, Barry Smith wrote:
>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Apr 24, 2012, at 1:39 PM, Mark F. Adams wrote:
>>>>>>>>>
>>>>>>>>>> Now I'm getting this error with code like this:
>>>>>>>>>>
>>>>>>>>>> ierr = MatGetSubMatrix( Cmat, new_eq_indices, new_eq_indices,
>>>>>>>>>> MAT_INITIAL_MATRIX, &mat );
>>>>>>>>>> CHKERRQ(ierr);
>>>>>>>>>> ierr = MatSetBlockSize( mat, cbs ); CHKERRQ(ierr);
>>>>>>>>>>
>>>>>>>>>> and like this:
>>>>>>>>>>
>>>>>>>>>> ierr = MatPtAP( Amat_fine, Pold, MAT_INITIAL_MATRIX, 2.0, &Cmat );
>>>>>>>>>> CHKERRQ(ierr);
>>>>>>>>>> ierr = MatSetBlockSize( Cmat, cbs ); CHKERRQ(ierr);
>>>>>>>>>
>>>>>>>>> Right you cannot do this. The matrix already exists so you cannot now
>>>>>>>>> set its size.
>>>>>>>>>
>>>>>>>>> Does Cmat have a block size of cbs
>>>>>>>>>
>>>>>>>>> What about Amat? By default these routines should create the new
>>>>>>>>> matrix with the correct blocksize.
>>>>>>>>>
>>>>>>>>> The harder part is if the blocksize of mat would be different than
>>>>>>>>> Cmat?
>>>>>>>>>
>>>>>>>>
>>>>>>>> It seems like MatGetSubMatrix should just inherit the block size but
>>>>>>>> PtAP is harder. The block size of the Cmat is the column block size
>>>>>>>> of P. But I can not set a column block size (!= row block size) so I
>>>>>>>> don't set block size on P at all. Here cbs is this column block size
>>>>>>>> of P, or what it should be.
>>>>>>>>
>>>>>>>> Mark
>>>>>>>>
>>>>>>>>> Barry
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Mark
>>>>>>>>>>
>>>>>>>>>> On Apr 23, 2012, at 9:09 PM, Barry Smith wrote:
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Yes, look, for example how ex32 is handled at the bottom of the
>>>>>>>>>>> makefile.
>>>>>>>>>>>
>>>>>>>>>>> Thanks
>>>>>>>>>>>
>>>>>>>>>>> Barry
>>>>>>>>>>>
>>>>>>>>>>> On Apr 23, 2012, at 5:50 PM, Mark F. Adams wrote:
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On Apr 23, 2012, at 5:59 PM, Barry Smith wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> It was changed a while ago that MatSetBlockSize() couldn't be set
>>>>>>>>>>>>> after the matrix was full instantiated. I guess that example did
>>>>>>>>>>>>> not get fixed because it is not listed in the makefile to run in
>>>>>>>>>>>>> the makeall.
>>>>>>>>>>>>
>>>>>>>>>>>> May I add it?
>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> I have fixed the example to call MatSetBlockSize() at a safe
>>>>>>>>>>>>> point.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Barry
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Apr 23, 2012, at 4:29 PM, Mark F. Adams wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> ex55.c in ksp is failing with:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> [0]PETSC ERROR: --------------------- Error Message
>>>>>>>>>>>>>> ------------------------------------
>>>>>>>>>>>>>> [0]PETSC ERROR: Arguments are incompatible!
>>>>>>>>>>>>>> [0]PETSC ERROR: Cannot change block size 1 to 2!
>>>>>>>>>>>>>> [0]PETSC ERROR:
>>>>>>>>>>>>>> ------------------------------------------------------------------------
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> on this line 57 of ex55.c:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> ierr = MatSetBlockSize(Amat,2); CHKERRQ(ierr);
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Any idea what happened here?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Mark
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>
>
