Dear Prof. Wolfgang,
Thank you very much for your quick answer! I have thinked about your
answers and debuged my code these days, and my question No.1 is still
unsolved, and question No.2 has been solved:
question No.1 : how to destroy sp efficiently? (unsolved)
As you say, I can destroy SparsityPattern by using the marked line below,
which is " m.reinit(); "
>{
> SparseMatrix m;
> SparsityPattern sp;
> ...fill sp, for example by copying from a DynamicSparsityPattern...
> m.reinit (sp); // m now points to sp
> ...some more code...
> m.reinit(); // ***
>}
But is I use the line directly, which means there isn't anything in the
brackets:
{
BlockSparseMatrix system_matrix;
BlockSparsityPattern sparsity_pattern_1;
[...]
sparsity_pattern_1.copy_from (dsp);
system_matrix.reinit (sparsity_pattern_1);
[...]
system_matrix.reinit ();
}
And the code cannot run, and the error is shown as :
error: no matching function for call to
‘dealii::BlockSparseMatrix<double>::reinit()’
system_matrix.reinit ();
If I define another BlockSparsityPattern : sparsity_pattern_2; then
{
BlockSparseMatrix system_matrix;
BlockSparsityPattern sparsity_pattern_1;
BlockSparsityPattern sparsity_pattern_2;
[...]
sparsity_pattern_1.copy_from (dsp);
sparsity_pattern_2.copy_from (dsp);
system_matrix.reinit (sparsity_pattern_1);
[...]
system_matrix.reinit (sparsity_pattern_2);
}
So the sparsity_pattern_1 is destroyed, but sparsity_pattern_2 cannot to be
destroyed, there is a BlockSparsityPattern object cannot be destroyed in
each time step, How to deal with it?
question No.2 : what differences between triangulation and
triangulation_active? (solved)
The definition of these two are:
GridGenerator::hyper_cube (triangulation_active, 0, 4.5);
triangulation_active.refine_global (8);
GridGenerator::flatten_triangulation (triangulation_active,
triangulation);
By using GridGenerator::flatten_triangulation, the level of triangulation
is 0, i.e. the coarsest mesh, which is used when define a periodic boundary
conditions. So triangulation.n_levels() is always 0. and cannot use
triangulation when determine which cell to be coarsen or refined:
if (triangulation.n_levels() > max_grid_level)
> for (typename Triangulation<dim>::active_cell_iterator
> cell = triangulation.begin_active(max_grid_level);
> cell != triangulation.end(); ++cell)
> cell->clear_refine_flag ();
So if we not only want to use triangulation.n_levels() like above,but also
want to use the coarsest mesh to define periodic boundary conditions, we
should learn from step-45, like this:
GridGenerator::hyper_cube (triangulation, 0, 4.5);
for (typename Triangulation<dim>::active_cell_iterator
cell = triangulation.begin_active();
cell != triangulation.end();
++cell)
{
for (unsigned int f=0; f<GeometryInfo<dim>::faces_per_cell;
++f)
{
if (cell->face(f)->at_boundary())
{
if (std::fabs(cell->face(f)->center()(0) - (4.5))
< 1e-12)
cell->face(f)->set_boundary_id (1);
else if(std::fabs(cell->face(f)->center()(1) -
(0)) < 1e-12)
cell->face(f)->set_boundary_id (2);
else if(std::fabs(cell->face(f)->center()(1)
- (4.5)) < 1e-12)
cell->face(f)->set_boundary_id (3);
else
if(std::fabs(cell->face(f)->center()(0) - (0)) < 1e-12)
{
cell->face(f)->set_boundary_id
(0);
}
}
}
}
triangulation.refine_global (3);
Hope the answer of question No.1. Thanks in advance.
Best,
Chucui
>
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