Hi All,
I'm trying to calculate J_tor= x*solution+solution_max/y
solution is already calculated vector from 3 function (setup_system,
assemble_system, solve)
To do this calculation I added the following three function(setup_Jtor,
assmeble_Jtor, solve_Jtor)
template <int dim>
void Step6<dim>::setup_Jtor ()
{
system_rhs.reinit(dof_handler.n_dofs()); //create global space for b
J_tor.reinit (dof_handler.n_dofs()); //create global space for x
system_matrix_Jtor.reinit (sparsity_pattern); //create global space for
A (in Ax=b)
}
template <int dim>
void Step6<dim>::assemble_Jtor ()
{
const QGauss<dim> quadrature_formula(2);
const RightHandSide<dim> right_hand_side;
FEValues<dim> fe_values (fe, quadrature_formula,
update_values | update_gradients |
update_quadrature_points | update_JxW_values);
const unsigned int dofs_per_cell = fe.dofs_per_cell;
const unsigned int n_q_points = quadrature_formula.size();
FullMatrix<double> cell_matrix (dofs_per_cell, dofs_per_cell); //create
local space for A
Vector<double> cell_rhs (dofs_per_cell); //create
local space for x
std::vector<double> sol_tmp(n_q_points); //create local space for
solution
std::vector<types::global_dof_index> local_dof_indices (dofs_per_cell);
typename DoFHandler<dim>::active_cell_iterator
cell = dof_handler.begin_active(),
endc = dof_handler.end();
//by Han(To get psi0)
Vector<double>::iterator max;
max=std::max_element(solution.begin(),solution.end());
for (; cell!=endc; ++cell)
{
fe_values.reinit (cell);
fe_values.get_function_values(solution,sol_tmp);
cell_matrix = 0;
cell_rhs = 0;
for (unsigned int q_index=0; q_index<n_q_points; ++q_index)
{
for(unsigned int i=0; i<dofs_per_cell; ++i) //local calculation for A
for(unsigned int j=0; j<dofs_per_cell; ++j)
cell_matrix(i,j) += (fe_values.shape_value (i, q_index) *
fe_values.shape_value (j, q_index) *
fe_values.JxW (q_index));
for(unsigned int i=0; i<dofs_per_cell; ++i) //local calculation for b
cell_rhs(i) += (fe_values.shape_value(i, q_index)*
right_hand_side.value(fe_values.quadrature_point(q_index),
sol_tmp[q_index],*max) *
fe_values.JxW (q_index));
}
cell->get_dof_indices (local_dof_indices);
for (unsigned int i=0; i<dofs_per_cell; ++i) //move calculated
values from local to global
for (unsigned int j=0; j<dofs_per_cell; ++j)
system_matrix_Jtor.add (local_dof_indices[i],
local_dof_indices[j],
cell_matrix(i,j));
for (unsigned int i=0; i<dofs_per_cell; ++i)
system_rhs(local_dof_indices[i]) += cell_rhs(i);
}
std::map<types::global_dof_index,double> boundary_values;
VectorTools::interpolate_boundary_values (dof_handler,
0,
ZeroFunction<dim>(),
boundary_values);
MatrixTools::apply_boundary_values (boundary_values,
system_matrix_Jtor,
solution,
system_rhs);
}
template <int dim>
void Step6<dim>::solve_Jtor ()
{
SolverControl solver_control (2000, 1e-12);
SolverCG<> solver (solver_control);
PreconditionSSOR<> preconditioner;
preconditioner.initialize(system_matrix_Jtor, 1.2);
solver.solve (system_matrix_Jtor, J_tor, system_rhs,
preconditioner);
}
In other words, I just calculated (pi_i,pi_j) x J_tor_j=(rhs_i,pi_i)
(where pi is test function)
It worked, the results are as I expected. But someone said to me it is very
inefficient way.
I agree with that opinion
But I have to access to Point(x and y), solution and maximum value of
solution to calculate J_tor
And, I also have to visualize J_tor using Visit.
Could you let me know how can I solve J_tor more efficiently using the
above three information?
Thank you.
Kyusik.
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