Re: [deal.II] Wrong result in use of FEEvaluation with different ConstraintMatrix objects

[Sambit Das]

Dear Martin,

Thank you for your quick reply. I understand my mistake now- the issue 
stems from "matrix_free_data.initialize_dof_vector(VECTOR_NAME, 1);" in the 
second 
case.  I have used matrix_free_data.initialize_dof_vector(VECTOR_NAME, 0) 
in both cases which causes a mismatch with the argument in the FEEvaluation 
in the second case. I was not running on debug
mode, which is why it didn't throw an error. I will use the dealii debug 
mode for such issues in the future.

Thank you again,
Best,
Sambit

On Saturday, December 2, 2017 at 6:57:26 AM UTC-6, Martin Kronbichler wrote:
>
> Dear Sambit, 
>
> If the result of the two cases is different and 
> ConstraintMatrix::distribute() was called in both cases, I expect there 
> to be some confusion regarding the indices of ghost entries. In debug 
> mode, there should be a check that the parallel partitioner of the 
> vector inside FEEvaluation::read_dof_values* does match with the 
> expected index numbering. Did you run in debug mode? To localize the 
> issue, can you check whether you called 
> "matrix_free_data.initialize_dof_vector(VECTOR_NAME, 1);" in the second 
> case? Note the optional argument "1" that must match with the "1" passed 
> to FEEvaluation. If the issue still appears, it must be because 
> ConstraintMatrix::distribute() does not do all updates. In that case, I 
> would appreciate if you can give us a workable example. 
>
> Best, 
> Martin 
>
>

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Re: [deal.II] Wrong result in use of FEEvaluation with different ConstraintMatrix objects

[Martin Kronbichler]

Dear Sambit,

If the result of the two cases is different and 
ConstraintMatrix::distribute() was called in both cases, I expect there 
to be some confusion regarding the indices of ghost entries. In debug 
mode, there should be a check that the parallel partitioner of the 
vector inside FEEvaluation::read_dof_values* does match with the 
expected index numbering. Did you run in debug mode? To localize the 
issue, can you check whether you called 
"matrix_free_data.initialize_dof_vector(VECTOR_NAME, 1);" in the second 
case? Note the optional argument "1" that must match with the "1" passed 
to FEEvaluation. If the issue still appears, it must be because 
ConstraintMatrix::distribute() does not do all updates. In that case, I 
would appreciate if you can give us a workable example.


Best,
Martin

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[deal.II] Wrong result in use of FEEvaluation with different ConstraintMatrix objects

[Sambit Das]

Hi All,

I have reduced my bug to the following minimal example: I create a 
MatrixFree object for two different ConstraintMatrices (provided as vector 
of ConstraintMatrices to the reinit(..)). 

matrix_free_data.reinit(dofHandlerVector, d_constraintsVector, 
quadratureVector, additional_data);

The dofHandlers are the same for both the ConstraintMatrices. Only 
difference- the first ConstraintMatrix has periodic constraints while the 
second one has no constraints. Next I run two cases

*  Case1: *

  FEEvaluation<3,FEOrder,FEOrder+1,1> phiTotEval(matrix_free_data,0, 0);
  const unsigned int numSubCells=matrix_free_data.n_components_filled(cell);
  const int numQuadPoints=phiTotEval.n_q_points;

  double phiTotRhoOutQuadSum=0.0;
  for (unsigned int cell=0; cellpoissonPtr->phiTotRhoOut); 
//phiTotRhoOut is a  parallel::distributed::Vector where I have previously 
called ConstraintMatrix(the one with periodic constraints)::distribute() 
and update_ghost_values()

// I have also called 
matrix_free_data.initialize_dof_vector(phiTotRhoOut) prior
phiTotEval.evaluate(true,true);

for (unsigned int q=0; q phiTotEval(matrix_free_data,1, 0);



I get different values of phiTotRhoOutQuadSumTotal for the two cases when 
run on multiple processors but same value when run on single processor. 
Comparing with a non-vectorized loop, case 1 which uses the periodic 
constraints gives the correct answer. However going by the manual, I 
expected the same value as I am using read_dof_values_plain(..) which 
doesn't take any constraints into account. I am wondering if I am doing 
anything wrong here.

Best,
Sambit

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