Dear Daniel,
Ok, I think I got it to work now, can you verify that it is correct or if I
have missed something crucial.
std::vector<double> x,y,z;
x.resize (dof_handler_scalar.n_dofs());
y.resize (dof_handler_scalar.n_dofs());
z.resize (dof_handler_scalar.n_dofs());
Quadrature<dim> quadrature_formula(fe_scalar.get_unit_support_points());
FEValues<dim> fe_values (fe, quadrature_formula,
update_values | update_quadrature_points);
FEValues<dim> fe_values_scalar (fe_scalar, quadrature_formula,
update_values | update_quadrature_points);
std::vector<Vector<double>> local_velocity_values
(quadrature_formula.size());
for (unsigned int i=0;i<quadrature_formula.size();i++)
local_velocity_values[i].reinit(dim);
const unsigned int dofs_per_cell = fe_scalar.dofs_per_cell;
std::vector<types::global_dof_index> local_dof_indices (dofs_per_cell);
typename DoFHandler<dim>::active_cell_iterator
cell_scalar = dof_handler_scalar.begin_active(),
endc_scalar = dof_handler_scalar.end();
typename DoFHandler<dim>::active_cell_iterator
cell = dof_handler.begin_active(),
endc = dof_handler.end();
for (; cell!=endc; ++cell, ++cell_scalar)
{
fe_values.reinit (cell);
fe_values_scalar.reinit (cell_scalar);
fe_values.get_function_values (solution,local_velocity_values);
cell_scalar->get_dof_indices (local_dof_indices);
for (unsigned int i=0; i<dofs_per_cell; ++i)
{
x[local_dof_indices[i]] = local_velocity_values[i](0);
y[local_dof_indices[i]] = local_velocity_values[i](1);
z[local_dof_indices[i]] = local_velocity_values[i](2);
}
}
I appreciate all your help,
Joel
On Wednesday, September 28, 2016 at 7:24:33 PM UTC+2, Daniel Arndt wrote:
>
> Joel,
>
> I did try it, but I cant just change the local_velocity_values from a
>> std::vector<Tensor<1,dim>> to std::vector<double>. Then the
>> fe_values[velocities].get_function_values function doesnt compile.
>>
> That's true, but you should use std::vector<Vector<double> > and not
> std::vector<double>, see also [1].
>
>
>> (correct me if wrong) This method of using norm_sqr() would only produce
>> the size, not the individual x,y and z components. I need the x,y and
>> z components separately so I can get the size but also the difference
>> between two solutions and that error of these two solutions. Hence my
>> previous message. I want to be able to manipulate the vector components.
>> How would I do this?
>>
> Yes, but since you get all the values at the local dofs, you can play
> around with them as you like and store the result in velocity. If this is
> not sufficient, you can also make velocity a std::vector and use something
> like
> velocity[component][local_dof_indices[i]] =
> local_velocity_values[i][component]
>
> Best,
> Daniel
>
>>
> [1]
> https://www.dealii.org/8.4.1/doxygen/deal.II/classFEValuesBase.html#a396f1430dd3f5716a9fe6ef2762edb5d
>
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