sim working correctly fully in fem

nufi/fields.h

@@ -76,8 +76,8 @@ inline double eval(double x, const PoissonProblem<1> &poisson,
 
   x = x - Parameters::LX * std::floor(x * Parameters::LX_INV); // in domain
 
-  return eval_point<1>(poisson.get_mapping(), poisson.get_dof_handler(),
-                       solution, Point<1>(x));
+  return eval_point_grad<1>(poisson.get_mapping(), poisson.get_dof_handler(),
+                            solution, Point<1>(x));
 }
 
 inline double integral_space_vector(const PoissonProblem<1> &poisson,

nufi/parameters.h

@@ -36,7 +36,7 @@ constexpr double DT = 1. / 8.;
 constexpr unsigned int TMAX = 100;
 
 // Plotting options
-constexpr int PLOT_FREQUENCY = 10;
+constexpr int PLOT_FREQUENCY = 4;
 constexpr size_t PLOT_NX = CALC_NX;
 constexpr double PLOT_DX = LX / PLOT_NX;
 } // namespace Parameters

nufi/poisson_problem.h

@@ -33,11 +33,14 @@
 #include <deal.II/fe/fe_values.h>
 
 #include <deal.II/numerics/data_out.h>
+#include <deal.II/numerics/fe_field_function.h>
 #include <deal.II/numerics/matrix_tools.h>
 #include <deal.II/numerics/vector_tools.h>
 
 #include <deal.II/numerics/vector_tools_evaluate.h>
 #include <deal.II/numerics/vector_tools_interpolate.h>
+#include <deal.II/numerics/vector_tools_point_gradient.h>
+#include <deal.II/numerics/vector_tools_point_value.h>
 #include <functional>
 #include <memory>
 #include <string>
@@ -170,14 +173,26 @@ PoissonProblem<dim>::sample_electric_potential(double x_min, double x_max,
 }
 
 template <int dim>
-double eval_point(const Mapping<dim> &mapping,
-                  const DoFHandler<dim> &dof_handler,
-                  const Vector<double> &solution, const Point<dim> &point) {
-  return VectorTools::point_value<dim>(mapping, dof_handler, solution, point);
+double
+eval_point_grad(const Mapping<dim> &mapping, const DoFHandler<dim> &dof_handler,
+                const Vector<double> &solution, const Point<dim> &point) {
+
+  Tensor<1, dim> grad =
+      VectorTools::point_gradient<dim>(mapping, dof_handler, solution, point);
+  double Ex = grad[0];
+
+  return Ex;
 }
 
-// dealii Poisson
+template <int dim>
+double eval_point_value(const Mapping<dim> &mapping,
+                        const DoFHandler<dim> &dof_handler,
+                        const Vector<double> &solution,
+                        const Point<dim> &point) {
 
+  return VectorTools::point_value<dim>(mapping, dof_handler, solution, point);
+}
+// dealii Poisson
 template <int dim> void PoissonProblem<dim>::create_mesh() {
 
   GridGenerator::hyper_cube(triangulation, Parameters::X_DOMAIN_LEFT,