Automatic update to Fenicsx 0.8 broke ufl.FiniteElement

Errors
1

Hello,
My working 0.7 installation was automatically upgraded from Ubuntu 22 PPAs to version 0.8 and is now broken. The following error was issued on previously working code:

Traceback (most recent call last):
  File "/home/bill/Cluster/Fenics2020/DielectricResonators/4Resonator/QuadResonatorFilterwMonopole.py", line 183, in <module>
    elem = ufl.FiniteElement('Nedelec 1st kind H(curl)', mesh.ufl_cell(), degree=2)
AttributeError: module 'ufl' has no attribute 'FiniteElement'. Did you mean: 'finiteelement'?

I also tried to change the attribute to “finiteelement” and it th efollowing error popped out:

Traceback (most recent call last):
  File "/home/bill/Cluster/Fenics2020/DielectricResonators/4Resonator/QuadResonatorFilterwMonopole.py", line 183, in <module>
    elem = ufl.finiteelement('Nedelec 1st kind H(curl)', mesh.ufl_cell(), degree=2)
TypeError: 'module' object is not callable

Has anyone else seen this error? How can I fix it?

2

Hi,

I think there have been some changes in the API. Look here.

3

cf. also Replace UFL elements with Basix elements in tests and demos by mscroggs · Pull Request #2381 · FEniCS/dolfinx · GitHub
(inspect the patches to the demos)

4

Thanks for the tip.
Following the Github notes, I added the basix importation lines

from slepc4py import SLEPc
from petsc4py import PETSc
from mpi4py import MPI as nMPI
import basix
import basix.ufl_wrapper
import meshio
import ufl
from dolfinx.mesh import locate_entities_boundary, meshtags
from dolfinx.io import gmshio
from dolfinx import fem
from dolfinx import io
from dolfinx.fem.petsc import LinearProblem
import gmsh

and changed the element creation lines to

    elem = basix.ufl_wrapper.create_element('Nedelec 1st kind H(curl)', mesh.ufl_cell().cellname(), degree=2)
    V = fem.FunctionSpace(mesh, elem)
    u = ufl.TrialFunction(V)
    v = ufl.TestFunction(V)

Unfortunately, I get an error that basix.ufl_wrapper does not exist.

ModuleNotFoundError: No module named 'basix.ufl_wrapper'
    import basix.ufl_wrapper

What is the correct way to define the element? Is the wrapper under another name?

5

You’re probably best to look at how it’s done in the demos (https://fenicsproject.org/documentation/).
DOLFINx documentation — DOLFINx 0.8.0 documentation

Other demos and tutorials are available at The FEniCSx tutorial — FEniCSx tutorial

For instance there are Nedelec examples at Electromagnetic scattering from a wire with perfectly matched layer condition — DOLFINx 0.8.0 documentation

6

I think it should be like this:

elem = basix.ufl.element("Nedelec 1st kind H(curl)", mesh.ufl_cell().cellname(), degree=2)
V = fem.functionspace(mesh, elem)
u = ufl.TrialFunction(V)
v = ufl.TestFunction(V)
7

Thanks for the links! They really helped. It is all working again. :white_check_mark: