> for (unsigned int i=0;i<dof_handler_total.n_dofs();i++)
> if (selected_dofs[i]==true)
> {
> sum+=vector_solution(i); ///where vector_solution is the
> vector that I want to integrate./
> nodes_number++; ///number of nodes belonging to the boundary
> out1./
> }
>
> double integral_per_surface=sum/nodes_number;
This can only work if you have a uniform mesh since you need to weigh the
contribution of all dofs by the surface element in the integral.
Why not do something like
double integral = 0;
for (cell=...)
for (f=0...)
if (cell->face(f)->at_boundary() &&
cell->face(f)->boundary_indicator == something interesting)
{
fe_face_values.reinit (cell, f);
fe_face_values.get_function_values (solution,
local_solution_values);
for (q=0; q<fe_face_values.n_quadrature_points; ++q)
integral += local_solution_values[q] * fe_face_values.JxW(q);
}
?
W.
-------------------------------------------------------------------------
Wolfgang Bangerth email: [email protected]
www: http://www.math.tamu.edu/~bangerth/
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