Quadrature elements constructed from non-Lagrange elements

[pbrubeck]

Enables quadrature spaces on a quadrature rule defined by a finat element

V = FunctionSpace(mesh, "CG", degree, variant="integral")

Q = FunctionSpace(mesh, "Quadrature", degree, quad_scheme=V.finat_element)

[pbrubeck]

This approach applied to RT1 gives a scalar FunctionSpace with the same DOFs and entity associations/continuity as Crouzeix-Raviart. The reference values of RT1 live on this space, but maybe CrossMeshInterpolator would want a fully-discontinuous vector-valued quadrature space.

[pbrubeck]

This approach applied to RT1 gives a scalar FunctionSpace with the same DOFs and entity associations/continuity as Crouzeix-Raviart. The reference values of RT1 live on this space, but maybe CrossMeshInterpolator would want a fully-discontinuous vector-valued quadrature space.

Maybe we shouldn't care about the discontinuities of the tangential components, as they are not involved in the DOFs. It should be fine as long as the normal component gets interpolated into the vector-valued quadrature space.