[petsc-users] MatSetSizes with blocked matrix

[Steena Monteiro]

Hi Matt,

Yes, the rest of the code is:

  ierr = MatSetBlockSize(A,2);CHKERRQ(ierr);
*  ierr = MatLoad(A,fd);CHKERRQ(ierr);*
  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
>
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