Hello everyone !
I have (another) a problem in my code. I am trying to mix *step-12* and
*step-31* for my project.
I want to solve two coupled equations (named *eq1* and *eq2*) that I am
solving in parallel just like in *step-31* but for one of them I am using
the Discontinuous Galerkin method like in *step-12* (*eq1*) and for the
other one I use standard Galerkin (*eq2*). I also have two *dof_handler*
like in *step-31* one for each equation. It looks like this :
*FESystem<dim> fe_eq1; //FE element for equation 1
FESystem<dim> fe_eq2; //FE element for equation 2
DoFHandler<dim> dof_handler_eq1; DoFHandler<dim>
dof_handler_eq2;*
And the constructor of the class :
* template <int dim> DG_FEM<dim>::DG_FEM () : fe_eq1
(FE_DGQ<dim>(1),40), fe_eq2 (FE_Q<dim>(1), 1), dof_handler_eq1
(triangulation), dof_handler_eq2 (triangulation) {}*
For the* eq1*, I am using like in *step-12* the *MeshWorker::mesh_loop(...)*
to fill my matrix :
In the *cell_worker* function, in order to access the ith component of my
shape function, I use the same technique as in *step-8*:
...
* const unsigned int n_dofs_per_cell =
scratch_data.fe_values.get_fe().dofs_per_cell; for (unsigned int i =
0; i < n_dofs_per_cell; ++i) { unsigned int component_i =
fe_eq1.system_to_component_index(i).first; // and then I access
the "component_i" of my shape function "i" at gauss point "point" using
copy_data.cell_rhs(i) += .... fe_v.shape_value_component(i, point,
component_i) ... }*
...
This seems to work fine. Since I have 40 components and 4 nodes, I have
*n_dofs_per_cell
= 160*. That is confirmed by the debuggeur.
My problem arises when I am using the same technique in the *face_worker*.
...
* const unsigned int n_dofs =
fe_iv.n_current_interface_dofs(); for (unsigned int i = 0; i <
n_dofs; ++i) { unsigned int component_i =
fe_eq1.system_to_component_index(i).first;
copy_data_face.cell_matrix(i, j) += * fe_iv.shape_value((beta_dot_n > 0),
j, qpoint, component_i) }*
...
Here *n_dofs = 320* and so *system_to_component_index()* does not like to
have an argument i>=160 and throws an error.
How come n_dofs=320 in this case ? I was expecting 2 interfaces * 2 nodes *
40 components = 160 dofs, unless I am considering all the interfaces of the
cell at onces in which case I have 2 interfaces * 4 nodes * 40 components =
320.
*My main question is therefore:*
How can I access the ith component of my shape function in face_worker like
in the cell_worker if I cannot use system_to_component_index() ?
Best regards,
Sylvain Mathonnière
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