Anders Logg wrote:
> On Thu, Feb 14, 2008 at 12:00:38PM +0100, Dag Lindbo wrote:
>>> Then I suggest first finding out which cells those points lie in, then
>>> then for each cell with a point get the expansion coefficients within
>>> that cell, then multiply those coefficients with the values of the
>>> basis functions at the points.
>>>
>>> The basis functions are available from the ufc::finite_element.
>>>
>> The searching part has been sorted out. How do I get the
>> ufc::finite_element from the function and/or the form? E.g.
>>
>> Function f(mesh, 0.0);
>> StokesTHBilinearForm a;
>> StokesTHLinearForm L(f);
>> LinearPDE pde(a, L, mesh, bcs);
>>
>> pde.set("PDE linear solver", "direct");
>> pde.solve(u, p);
>>
>> ufc::form frm = a.form(); // form() is virtual
>> ufc::finite_element fe = frm.create_finite_element();
>
> You should be able to do this:
>
> // Create element (the '0' means create it for the space used for the
> // first argument in the form, '1' for second etc)
> ufc::finite_element* element = a.form().create_finite_element(0);
Thanks! In my case element->space_dimension() return 15 (dofs) which
makes sense, since I have a Taylor-Hood element (but will problably
switch later). However, I only want to pick out the velocity components.
How should a mixed element be handled?
I have(u is a Function):
Cell cell(mesh,cell_nr);
UFCCell ufc_cell(cell);
ufc::finite_element* fe = a->form().create_finite_element(0);
ufc::dof_map* ufc_dof_map = a->form().create_dof_map(0);
DofMap* dof_map = new DofMap(*ufc_dof_map, mesh);
unsigned int* dofs = new unsigned int[dof_map->local_dimension()];
real* basis_values = new real[fe->space_dimension()];
real* dof_values = new real[fe->space_dimension()];
Vector vec = u.vector();
dof_map->tabulate_dofs(dofs,ufc_cell);
vec.get(dof_values, dof_map->local_dimension(), dofs);
>
> // Use it for a while
> element->tabulate_basis(...);
> ...
>
> // Then delete it
> delete element;
>
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