Hi David,
I am working on fluid-fluid coupling. My goal is to create matrices that
correspond to the interface so that I can put them in 0,1 and 1,0 blocks of
the system matrix.
Here is what I am doing for one of these matrices:
BlockSparseMatrix<double> system_matrix12;
BlockSparsityPattern non_diag_sparsity_pattern12;
BlockSparseMatrix<double> system_matrix;
BlockSparsityPattern sparsity_pattern;
non_diag_sparsity_pattern12.reinit(2,2);
non_diag_sparsity_pattern12.block(0,0).reinit(dof_u,dof_u2,2*fe1.dofs_per_cell
+ 2*fe2.dofs_per_cell);
non_diag_sparsity_pattern12.block(0,1).reinit(dof_u,dof_p2,2*fe1.dofs_per_cell
+ 2*fe2.dofs_per_cell);
non_diag_sparsity_pattern12.block(1,0).reinit(dof_p,dof_u2,2*fe1.dofs_per_cell
+ 2*fe2.dofs_per_cell);
non_diag_sparsity_pattern12.block(1,1).reinit(dof_p,dof_p2,2*fe1.dofs_per_cell
+ 2*fe2.dofs_per_cell); //max_per_row is chosen arbitrarily big since
I'll compress it later
// I iterate over the cells and their faces and in a way check to see if
cell1(face_no1) == cell2(face_no2), then (meshes are matching from the
both side)
fe_face_values1.reinit (cell1, face_no1);
fe_face_values2.reinit (cell2, face_no2);
std::vector<types::global_dof_index> local_dof_indices1 (fe1.dofs_per_cell);
std::vector<types::global_dof_index> local_dof_indices2 (fe2.dofs_per_cell);
cell1->get_dof_indices (local_dof_indices1);
cell2->get_dof_indices (local_dof_indices2);
for (unsigned int i=0; i<fe1.dofs_per_cell; ++i)
for (unsigned int j=0; j<fe2.dofs_per_cell; ++j)
{
if (local_dof_indices1[i] < dof_u && local_dof_indices2[j] < dof_u2)
{
non_diag_sparsity_pattern12.block(0,0).add(local_dof_indices1[i],local_dof_indices2[j]);
}
else if(local_dof_indices1[i] < dof_u && local_dof_indices2[j] >=
dof_u2)
{
non_diag_sparsity_pattern12.block(0,1).add(local_dof_indices1[i],local_dof_indices2[j]
- dof_u2);
}
else if(local_dof_indices1[i] >= dof_u && local_dof_indices2[j] <
dof_u2)
{
non_diag_sparsity_pattern12.block(1,0).add(local_dof_indices1[i] -
dof_u,local_dof_indices2[j]);
}
else
{
non_diag_sparsity_pattern12.block(1,1).add(local_dof_indices1[i] -
dof_u,local_dof_indices2[j] - dof_u2);
}
}
non_diag_sparsity_pattern12.compress();
sparsity_pattern.compress();
sparsity_pattern.block(0,2).copy_from(non_diag_sparsity_pattern12.block(0,0));
sparsity_pattern.block(0,3).copy_from(non_diag_sparsity_pattern12.block(0,1));
sparsity_pattern.block(1,2).copy_from(non_diag_sparsity_pattern12.block(1,0));
sparsity_pattern.block(1,3).copy_from(non_diag_sparsity_pattern12.block(1,1));
//Other blocks of the global sparsity pattern
were copied same way.
system_matrix.clear();
system_matrix12.clear();
system_matrix.reinit(sparsity_pattern);
system_matrix12.reinit(non_diag_sparsity_pattern12);
To check the problem:
std::cout << system_matrix11.m() << std::endl;
std::cout << system_matrix12.m() << std::endl;
std::cout << system_matrix.m() << std::endl;
std::cout <<
non_diag_sparsity_pattern12.block(0,0).max_entries_per_row() << std::endl;
std::cout << sparsity_pattern.block(3,0).n_rows()<< std::endl;
Results:
659 initialized with a pattern created by make_sparsity_pattern
code, so no problem at all
0 initialized with manually added sparsity pattern
0 same goes here
31 manually added non-diag sparsity pattern looks non-empty
81 manually added global sparsity pattern also looks non-empty
As their sparsity patterns look to be created correctly, system matrices
initialized with these sparsity patterns looks empty.
Thanks,
Mustafa.
On Sat, Dec 15, 2018 at 2:04 AM David Wells <[email protected]> wrote:
> Hi Mustafa,
>
> This does sound strange: BlockSparseMatrix::m() should return the number
> of rows of blocks (which is clearly 4 in your code).
>
> Would it be possible for you to post a more complete code fragment that
> shows the problem? I cannot figure out where the problem is with what you
> posted.
>
> Thanks,
> David Wells
>
> On Friday, December 14, 2018 at 8:41:10 AM UTC-5, Mustafa Aggul wrote:
>>
>> Hello,
>> I have created my own block sparsity pattern by adding non-zero entries
>> manually, and then compressed it. Upon some testings on this sparsity
>> pattern, I have realized that it is indeed created correctly, in terms of
>> dimension and number of elements it has. However, the system matrix that I
>> initialized with this sparsity pattern looks empty (system_matrix.m() = 0).
>> What would be the possible reason for this?
>> Thanks for any response in advance,
>>
>> sparsity_pattern.reinit(4,4);
>>
>> if(something happens)
>> sparsity_pattern.block(0,0).add(local_dof_indices1[i],local_dof_indices2[j]);
>> //these kind of operations
>> sparsity_pattern.compress();
>> system_matrix.reinit(sparsity_pattern);
>>
>> --
>> *Mustafa Ağgül*
>> *Department of Mathematics*
>> *Michigan Technological University*
>> *1400 Townsend Drive*
>> *Houghton, Michigan 49931-1295*
>> *Tel: 906-487-3135*
>>
> --
> The deal.II project is located at http://www.dealii.org/
> For mailing list/forum options, see
> https://groups.google.com/d/forum/dealii?hl=en
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--
*Mustafa Ağgül*
*Department of Mathematics*
*Michigan Technological University*
*1400 Townsend Drive*
*Houghton, Michigan 49931-1295*
*Tel: 906-487-3135*
--
The deal.II project is located at http://www.dealii.org/
For mailing list/forum options, see
https://groups.google.com/d/forum/dealii?hl=en
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