[petsc-users] MatSetSizes with blocked matrix

[Matthew Knepley]

On Tue, Mar 15, 2016 at 12:14 PM, Steena Monteiro <steena.hpc at gmail.com>
wrote:

> Hi Matt,
>
> Yes, the rest of the code is:
>
>   ierr = MatSetBlockSize(A,2);CHKERRQ(ierr);
> *  ierr = MatLoad(A,fd);CHKERRQ(ierr);*
>

So, are you saying that

  1) You have a matrix with odd total dimension

  2) You set the block size of the initial matrix to 2

  3) You load the matrix

and there is no error? Can you make a simple example with a matrix of size
5?
I can put in the relevant error checking.

  Thanks,

     Matt


>   ierr = MatCreateVecs(A, &x, &y);CHKERRQ(ierr);
>
>
>   ierr =  VecSetRandom(x,NULL); CHKERRQ(ierr);
>   ierr = VecSet(y,zero); CHKERRQ(ierr);
>   ierr = MatMult(A,x,y); CHKERRQ(ierr);
>
>
>   ierr = PetscViewerDestroy(&fd);CHKERRQ(ierr);
>   ierr = MatDestroy(&A);CHKERRQ(ierr);
>   ierr = VecDestroy(&x);CHKERRQ(ierr);
>   ierr = VecDestroy(&y);CHKERRQ(ierr);
>
> Thanks,
> Steena
>
>
> On 15 March 2016 at 09:15, Matthew Knepley <knepley at gmail.com> wrote:
>
>> On Tue, Mar 15, 2016 at 11:04 AM, Steena Monteiro <steena.hpc at gmail.com>
>> wrote:
>>
>>> I pass a binary, matrix data file at the command line and load it into
>>> the matrix:
>>>
>>> PetscInitialize(&argc,&args,(char*)0,help);
>>> ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRQ(ierr);
>>>
>>> /* converted mtx to dat file*/
>>> ierr = PetscOptionsGetString(NULL,"-f",file,PETSC_MAX_PATH_LEN,&flg);
>>> CHKERRQ(ierr);
>>>
>>> if (!flg) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_USER,"specify matrix dat
>>> file with -f");
>>>
>>>  /* Load matrices */
>>> ierr =
>>> PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,FILE_MODE_READ,&fd);CHKERRQ(ierr);
>>> ierr =
>>> PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,FILE_MODE_READ,&fd);CHKERRQ(ierr);
>>> ierr = MatCreate(PETSC_COMM_WORLD,&A);CHKERRQ(ierr);
>>> ierr = MatSetFromOptions(A);CHKERRQ(ierr);
>>>
>>
>> Nothing above loads a matrix. Do you also call MatLoad()?
>>
>>   Matt
>>
>>
>>> Thanks,
>>> Steena
>>>
>>> On 15 March 2016 at 08:58, Matthew Knepley <knepley at gmail.com> wrote:
>>>
>>>> On Tue, Mar 15, 2016 at 10:54 AM, Steena Monteiro <steena.hpc at gmail.com
>>>> > wrote:
>>>>
>>>>> Thank you, Dave.
>>>>>
>>>>> Matt: I understand the inconsistency but MatMult with non divisible
>>>>> block sizes (here, 2) does not throw any errors and fail, when MatSetSize
>>>>> is commented out. Implying that 1139905 global size does work with block
>>>>> size 2.
>>>>>
>>>>
>>>> If you comment out MatSetSize(), how does it know what size the Mat is?
>>>>
>>>>    Matt
>>>>
>>>>
>>>>> On 15 March 2016 at 00:12, Dave May <dave.mayhem23 at gmail.com> wrote:
>>>>>
>>>>>>
>>>>>> On 15 March 2016 at 04:46, Matthew Knepley <knepley at gmail.com> wrote:
>>>>>>
>>>>>>> On Mon, Mar 14, 2016 at 10:05 PM, Steena Monteiro <
>>>>>>> steena.hpc at gmail.com> wrote:
>>>>>>>
>>>>>>>> Hello,
>>>>>>>>
>>>>>>>> I am having difficulty getting MatSetSize to work prior to using
>>>>>>>> MatMult.
>>>>>>>>
>>>>>>>> For matrix A with rows=cols=1,139,905 and block size = 2,
>>>>>>>>
>>>>>>>
>>>>>>> It is inconsistent to have a row/col size that is not divisible by
>>>>>>> the block size.
>>>>>>>
>>>>>>
>>>>>>
>>>>>> To be honest, I don't think the error message being thrown clearly
>>>>>> indicates what the actual problem is (hence the email from Steena). What
>>>>>> about
>>>>>>
>>>>>> "Cannot change/reset row sizes to 400000 local 1139906 global after
>>>>>> previously setting them to 400000 local 1139905 global. Local and global
>>>>>> sizes must be divisible by the block size"
>>>>>>
>>>>>>
>>>>>>>
>>>>>>>   Matt
>>>>>>>
>>>>>>>
>>>>>>>> rank 0 gets 400000 rows and rank 1 739905 rows,  like so:
>>>>>>>>
>>>>>>>> /*Matrix setup*/
>>>>>>>>
>>>>>>>>
>>>>>>>> ierr=PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,FILE_MODE_READ,&fd);
>>>>>>>> ierr = MatCreate(PETSC_COMM_WORLD,&A);
>>>>>>>> ierr = MatSetFromOptions(A);
>>>>>>>> ierr = MatSetType(A,MATBAIJ);
>>>>>>>> ierr = MatSetBlockSize(A,2);
>>>>>>>>
>>>>>>>> /*Unequal row assignment*/
>>>>>>>>
>>>>>>>>  if (!rank) {
>>>>>>>>     ierr = MatSetSizes(A, 400000, PETSC_DECIDE,
>>>>>>>> 1139905,1139905);CHKERRQ(ierr);
>>>>>>>>    }
>>>>>>>> else {
>>>>>>>>     ierr = MatSetSizes(A, 739905, PETSC_DECIDE,
>>>>>>>> 1139905,1139905);CHKERRQ(ierr);
>>>>>>>> }
>>>>>>>>
>>>>>>>> MatMult (A,x,y);
>>>>>>>>
>>>>>>>> /************************************/
>>>>>>>>
>>>>>>>> Error message:
>>>>>>>>
>>>>>>>> 1]PETSC ERROR: [0]PETSC ERROR: No support for this operation for
>>>>>>>> this object type
>>>>>>>> Cannot change/reset row sizes to 400000 local 1139906 global after
>>>>>>>> previously setting them to 400000 local 1139905 global
>>>>>>>>
>>>>>>>> [1]PETSC ERROR: [0]PETSC ERROR: Cannot change/reset row sizes to
>>>>>>>> 739905 local 1139906 global after previously setting them to 739905 local
>>>>>>>> 1139905 global
>>>>>>>>
>>>>>>>> -Without messing with row assignment,  MatMult works fine on this
>>>>>>>> matrix for block size = 2, presumably because an extra padded row is
>>>>>>>> automatically added to facilitate blocking.
>>>>>>>>
>>>>>>>> -The above code snippet works well for block size = 1.
>>>>>>>>
>>>>>>>> Is it possible to do unequal row distribution *while using
>>>>>>>> blocking*?
>>>>>>>>
>>>>>>>> Thank you for any advice.
>>>>>>>>
>>>>>>>> -Steena
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> 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
>>>>
>>>
>>>
>>
>>
>> --
>> 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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