And for the record, attached is a corrected version of the MWE illustrating
the correct and intended behaviour of constraint creation for pure
p-refinement.
Number of cells: 2
Number of degrees of freedom: 11
Number of constraints: 1
On Saturday, August 27, 2016 at 9:41:41 AM UTC+2, Jean-Paul Pelteret wrote:
>
> Ha ha. Dammit, what a silly mistake :-) Thanks Wolfgang!
>
> On Friday, August 26, 2016 at 11:08:17 PM UTC+2, Wolfgang Bangerth wrote:
>>
>> On 08/25/2016 02:34 AM, Jean-Paul Pelteret wrote:
>> > Hi Deepak,
>> >
>> > Ok, so I've created a minimal working example to demonstrate what
>> you're
>> > seeing here. I'm not sufficiently familiar with the p-refinement part
>> of the
>> > hp functionality/implementation to tell whether this is truly the
>> expected
>> > behaviour or not. I see that the examples and description
>> > <
>> https://www.dealii.org/8.4.1/doxygen/deal.II/group__constraints.html#ga3eaa31a679484e80c193e74e8a967dc8>
>>
>>
>> > in the documentation mix h- and p-refinement, so are _perhaps_ not
>> > sufficiently clear to describe the expected outcome of this
>> configuration. Or
>> > maybe its a bug arising from the adjacent cells being on the same
>> refinement
>> > level (i.e. there are no actual hanging _nodes_). Perhaps someone else
>> could
>> > clarify this?
>>
>> It's not a bug but a feature :-) In your code, you call
>>
>>
>> // Build constraints
>> ConstraintMatrix constraints;
>> DoFTools::make_hanging_node_constraints (dof_handler,
>> constraints);
>> constraints.clear(); // *************
>>
>> I suspect what you really wanted to call in the last line is
>> 'constraints.close()' -- because if you do so, the result is pretty much
>> what
>> I think you probably wanted ;-)
>>
>> Cheers
>> W.
>>
>> --
>> ------------------------------------------------------------------------
>> Wolfgang Bangerth email: bange...@colostate.edu
>> www: http://www.math.colostate.edu/~bangerth/
>>
>>
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#include <deal.II/dofs/dof_handler.h>
#include <deal.II/dofs/dof_tools.h>
#include <deal.II/fe/fe_q.h>
#include <deal.II/fe/fe_values.h>
#include <deal.II/grid/grid_generator.h>
#include <deal.II/grid/tria.h>
#include <deal.II/grid/tria_accessor.h>
#include <deal.II/grid/tria_iterator.h>
#include <deal.II/hp/dof_handler.h>
#include <deal.II/hp/fe_collection.h>
#include <deal.II/hp/fe_values.h>
#include <deal.II/lac/constraint_matrix.h>
#include <deal.II/numerics/data_out.h>
#include <iostream>
#include <fstream>
using namespace dealii;
int main()
{
const int dim = 2;
Triangulation<dim> tria;
const hp::FECollection<dim> fe_collection (FE_Q<dim>(1), FE_Q<dim>(2));
hp::DoFHandler<dim> dof_handler(tria);
// Two cell domain
std::vector<unsigned int> divisions (dim,1);
divisions[0] = 2;
Point<dim> pt_1, pt_2;
for (unsigned int d=0; d<dim; ++d)
pt_2[d] = 1.0;
GridGenerator::subdivided_hyper_rectangle(tria, divisions, pt_1, pt_2);
// Set active FE index (p-refinement level; default index is 0)
dof_handler.begin_active()->set_active_fe_index(1);
dof_handler.distribute_dofs(fe_collection);
// Build constraints
ConstraintMatrix constraints;
DoFTools::make_hanging_node_constraints (dof_handler,
constraints);
constraints.close();
// Print to screen
std::cout
<< "Number of cells: " << tria.n_active_cells() << "\n"
<< "Number of degrees of freedom: " << dof_handler.n_dofs() << "\n"
<< "Number of constraints: " << constraints.n_constraints() << "\n";
// Output p-refinement level
Vector<double> p_refinement (tria.n_active_cells());
unsigned int cell_no = 0;
for (typename hp::DoFHandler<dim>::active_cell_iterator
cell = dof_handler.begin_active();
cell != dof_handler.end(); ++cell, ++cell_no)
{
p_refinement[cell_no] = cell->active_fe_index();
}
DataOut<dim,hp::DoFHandler<dim> > data_out;
data_out.attach_dof_handler (dof_handler);
data_out.add_data_vector (p_refinement, "p_refinement_level");
data_out.build_patches ();
std::ostringstream filename;
filename << "solution.vtk";
std::ofstream output (filename.str().c_str());
data_out.write_vtk (output);
return 0;
}
