On Thu, Dec 12, 2013 at 10:59 AM, Andrew Donaldson Davis
<davi...@mit.edu> wrote:
> Hi,
>
> I am trying to get the spatial points corresponding to the degrees of
> freedom for a specific variable in a libMesh::System. However, I am having
> some trouble if the degree of the variable's shape functions is less than
> the mesh. Here is the code I am using
>
> int varNum = 0
> set<libMesh::dof_id_type> dofIndices;
> system.local_dof_indices(varNum, dofIndices);
>
> const libMesh::MeshBase& mesh =system.get_mesh();
>
> for (auto dofIter = dofIndices.begin(); dofIter != dofIndices.end();
> ++dofIter) {
> libMesh::Point pt = mesh.point(*dofIter);
> cout << pt << endl;
> }
>
> This works fine if, for example, varNum is order 2 and the mesh is
> libMesh::QUAD9. However, if varNum is linear (order) and the mesh still
> libMesh::QUAD9 I am not getting the correct subset of mesh points. It
> looks like the set dofIndices contains the numbers 1,2,3,...,N, which I
> believe give the first N points in the mesh. I expected dofIndices not to
> contain sequential numbers. Shouldn't it skip some on each element
> (corresponding to the DOFs that aren't used by the basis)? Does anyone
> know a better way to accomplish this?
I guess it would depend on the node numbering in your mesh? Is it
possible that the first N nodes are actually the corner vertices of
the QUAD9s and hence correspond to the DOF ids for the linear finite
element?
Is your mesh created via build_square()?
--
John
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