[petsc-dev] MetSetBlockSize issue
Mark F. Adams
mark.adams at columbia.edu
Tue Apr 24 20:14:25 CDT 2012
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.
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
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>
>
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