2016년 10월 5일 수요일 오전 1시 17분 31초 UTC+9, Wolfgang Bangerth 님의 말:
>
> On 10/04/2016 09:12 AM, hank...@gmail.com <javascript:> wrote:
> >
> > template <int dim>
> > void Step6<dim>::get_profile ()
> > {
> > const QGauss<dim> quadrature_formula(3);
> > 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();
> >
> > 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();
> > f.reinit (dof_handler.n_dofs()); //f is already declared as private
> > like solution
> >
> > for (; cell!=endc; ++cell)
> > {
> > fe_values.reinit (cell);
> >
> > for (unsigned int q_index=0; q_index<n_q_points; ++q_index)
> > {
> > const Point<dim> &p=fe_values.quadrature_point(q_index);
> >
> > f[q_index]=p(0)*solution[q_index]+p(1);
>
> 'solution' is a global vector of the values for each degree of freedom.
> But you index it with the quadrature point number. That makes no sense.
>
> What you need to do is evaluate the solution at the quadrature points.
> This is done using the
> FEValues::get_function_values()
> function. Several example programs use it, so you will find use cases
> there.
>
> Best
> W.
>
> --
> ------------------------------------------------------------------------
> Wolfgang Bangerth email: bang...@colostate.edu
> <javascript:>
> www: http://www.math.colostate.edu/~bangerth/
>
First of all, Thank you very much indeed for your kind reply.
I'm sorry to have bothered you... But, Could I have one more question...??
In your lecture 31.65, you used the gradient of previous solution in the
assemble_system() by using of previous_solution_gradient[q_index].
So,like you used previous_solution_gradient[q_index], I also wanted to use
previous_solution[q_index] in the assemble_system()
But, according to what you mentioned above, what I have done with
previous_solution[q_index] is wrong....(Because previous_solution is
declared as global vector like solution)
So, my question is that If I want to use previous solution in the
assemble_system, Do I have to use FEValues::get_function_values() not
previous_solution[ ] that is global vector?
Thank you
Kyusik
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