On 3/29/22 19:26, Léonhard YU wrote:
1) cell_mass_matrix(i, j) += rho * fe_values.shape_value(i, q_point) *
fe_values.shape_value(j, q_point) * fe_values.JxW(q_point);
Yes, this is not correct unless you prefix it with
if (fe.system_to_component_index(i).first ==
fe.system_to_component_index(j).first)
2) cell_mass_matrix(i, j) +=
(mass_phi_i * mass_phi_j) *
fe_values.JxW(q_point) * rho;
where mass_phi_i:
const Tensor<2, dim>
mass_phi_i =get_mass_matrix(fe_values, i, q_point);
(using this function)
template <int dim>
inline Tensor<2, dim> get_mass_matrix(const FEValues<dim> &fe_values,
const unsigned int shape_func_i,
const unsigned int shape_func_j,
const unsigned int q_point)
{
Tensor<2, dim> tmp;
for (unsigned int t = 0; t < dim; ++t)
for (unsigned int k = 0; k < dim; ++k)
{
tmp[t][k] = fe_values.shape_value_component(shape_func_i,
q_point, t)*
fe_values.shape_value_component(shape_func_j,
q_point, k);
}
return tmp;
}
I don't understand this code. You say
const Tensor<2, dim> mass_phi_i
= get_mass_matrix(fe_values, i, q_point);
but the definition of get_mass_matrix() takes four arguments.
2) cell_mass_matrix(i, j) +=
(mass_phi_i * mass_phi_j) *
fe_values.JxW(q_point) * rho;
where mass_phi_i:
const SymmetricTensor <2, dim>
mass_phi_i =get_mass_matrix(fe_values, i, q_point);
(using this function)
template <int dim>
inline SymmetricTensor<2, dim>
get_mass_matrix (const FEValues<dim> &fe_values,
const unsigned int shape_func,
const unsigned int q_point)
{
SymmetricTensor<2, dim> tmp;
for (unsigned int i = 0; i < dim; ++i)
tmp[i][i] = fe_values.shape_value_component(shape_func, q_point, i) *
fe_values.shape_value_component(shape_func,
q_point, i);
for (unsigned int i = 0; i < dim; ++i)
for (unsigned int j = i + 1; j < dim; ++j)
tmp[i][j] =
fe_values.shape_value_component(shape_func, q_point, i) *
fe_values.shape_value_component(shape_func, q_point, j);
return tmp;
}
This suffers from the same problem.
I think you want to read through the module on vector-valued problems to
understand the general philosophy about dealing with vector problems.
Best
W.
--
------------------------------------------------------------------------
Wolfgang Bangerth email: [email protected]
www: http://www.math.colostate.edu/~bangerth/
--
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
---
You received this message because you are subscribed to the Google Groups "deal.II User Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/dealii/42ff523d-ecae-e8dd-6417-2cf620301c87%40colostate.edu.
