On 07/22/2016 05:10 PM, Junchao Zhang wrote:
In matrix assembly, I need to access solution values of the previous
time-step at DoFs of the current cell. Is my following code correct? I could
not find an example. Thanks.
std::vector<types::global_dof_index> local_dof_indices (dofs_per_cell);
...
for(; cell!=endc; ++cell) {
if (cell->is_locally_owned()) {
cell->get_dof_indices (local_dof_indices);
fe_values.reinit (cell);
... += old_locally_relevant_solution(local_dof_indices[i]);
}
}
No. You typically need to access the old solution at *quadrature points*, not
at the node points. You can find how this is typically done in many tutorial
programs, e.g., in steps 21, 26, 15. To evaluate a solution at the quadrature
points, you'll have to do something like
fe_values.get_function_values (old_solution,
old_solution_values);
Best
W.
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