Dear community
I am asking your help today about imposing affine constraints. I understood
well example 6, but when it comes to apply it to sparse MPI matrices I get
lost. I am not sure if example 27 is of help for my case.
What would I like to simulate? Take two separate domains, with conformal
meshes. I want to impose that two sets of nodes share the same solution,
i.e. the solution field is continuous. To this aim, the dofs to be tied
have been collected in a set of pairs (which has been verified, it is OK).
Hence, say the set is named tie_table, the dof tie_table.first shall be
equal to tie_table.second .
So far so good, but from now on it blurs to me. I figured out that I shall
build the affine constraint (say it is named m_interfaces_constraints) and
update the sparsity pattern (say it is named dsp).
The dsp has been created after the hanging node constraints
DoFTools::make_flux_sparsity_pattern( this->dof_handler,
dip,
this->hanging_node_constraints,
/*keep constrained dofs*/ false);
and it has been updated afterwards like that:
for (auto tie_table_ii : tie_table )
{
if ( tie_table_ii.first < tie_table_ii.second )
// we shall make sure not to impose a tie twice ...
{
dsp->add( tie_table_ii.first, tie_table_ii.second ) ;
dsp->add( tie_table_ii.second, tie_table_ii.first ) ;
m_interfaces_constraints.add_line( tie_table_ii.first );
m_interfaces_constraints.add_entry( tie_table_ii.first,
tie_table_ii.second, 1 );
}
}
m_interfaces_constraints.close();
Is the above reasonable to build the m_interfaces_constraints? Am I missing
something? At this point how shall I proceed in distributing the cell
matrix into the system matrix in the assembly phase? The following code
does not seem to work.
... make entries in cell_matrix, cell_rhs ...
cell->get_dof_indices (local_dof_indices);
this->hanging_node_constraints.distribute_local_to_global(cell_matrix,
cell_rhs,
local_dof_indices,
this->system_matrix, this->system_rhs);
this->m_interfaces_constraints.distribute_local_to_global(cell_matrix,
cell_rhs,
local_dof_indices,
this->system_matrix, this->system_rhs);
specifically, the instruction
this->m_interfaces_constraints.distribute_local_to_global generates the
following error:
--------------------------------------------------------
An error occurred in line <1683> of file
</var/folders/py/_sybqp9s7pn6y633bs_bqyp00000gn/T/albertosalvadori/spack-stage/spack-stage-dealii-9.2.0-ujawazz34bb5ybgxwfovovdrwaem4ymj/spack-src/source/lac/trilinos_sparse_matrix.cc>
in function
void dealii::TrilinosWrappers::SparseMatrix::add(const
dealii::TrilinosWrappers::SparseMatrix::size_type, const
dealii::TrilinosWrappers::SparseMatrix::size_type, const
dealii::TrilinosWrappers::SparseMatrix::size_type *, const
dealii::TrilinosScalar *, const bool, const bool)
The violated condition was:
ierr == 0
Additional information:
An error with error number 2 occurred while calling a Trilinos function
--------------------------------------------------------
Finally, shall I call this function? What does it do?
m_interfaces_constraints.condense(*dsp);
I appreciate your help, very much.
Alberto
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