### Support for H1 BrokenElement in FunctionSpace

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11 months ago by
Hi all,

I have a question for the developers.
I'm interested in storing elemental matrices in the form a large sparse block-diagonal matrix.

To this aim, I have tried using the BrokenElement class.
My question is: Is there a mathematical/implementation reason because of which a FunctionSpace with BrokenElement can not be constructed?

Consider the following code:

import dolfin as dl
mesh = dl.UnitSquareMesh(1,1)
elH1 = dl.FiniteElement("Lagrange", mesh.ufl_cell(), 1)
elH1_b = dl.BrokenElement(elH1)
Vh = dl.FunctionSpace(mesh, elH1_b)​

The code gives a segmentation fault with error:

Calling FFC just-in-time (JIT) compiler, this may take some time.
Cannot handle this element type: BrokenElement(<CG1 on a triangle>)

Which FEniCS package is raising the error? Is there a walk-around?

An alternative could be using DG. However, do the DG spaces differ from their corresponding CG version only at the DofMap level or also in term of shape functions?

Umberto

Community: FEniCS Project