[BUG]: Facet-to-vertex and facet-to-edge connectivities in prism mesh are missing triangular facets

[schnellerhase]

Summarize the issue

The connectivities (2,0) (facet-to-vertex) and (2, 1) (facet-to-edge) are missing the triangular facets in a prism mesh.

How to reproduce the bug

Run the MWE below. For a more detailed description of the problem see here

Minimal Example (Python)

from dolfinx.mesh import create_box, CellType
from mpi4py import MPI

mesh = create_box(MPI.COMM_WORLD, [[0, 0, 0], [1, 1, 1]], [1, 1, 1], CellType.prism)

print("Connectivity (2, 0)")
mesh.topology.create_connectivity(2, 0)
f_to_v = mesh.topology.connectivity(2, 0)
for i in range(f_to_v.num_nodes):
    print(f_to_v.links(i))

print("\nConnectivity (2, 1)")
mesh.topology.create_connectivity(2, 1)
f_to_v = mesh.topology.connectivity(2, 1)
for i in range(f_to_v.num_nodes):
    print(f_to_v.links(i))

Output (Python)

Connectivity (2, 0)
[0 1 3 4]
[0 2 3 5]
[1 2 4 5]
[1 4 6 7]
[2 5 6 7]

Connectivity (2, 1)
[0 2 4 8]
[1 2 6 9]
[ 3  4  6 10]
[ 4  5 11 13]
[ 6  7 12 13]

especially we do not retrieve the front and back facets, in the case of the (2,0) connectivity, given by: [0, 1, 2], [1, 2, 6], [3, 4, 5] and [4, 5, 7]

Version

main branch

DOLFINx git commit

No response

Installation

No response

Additional information

No response

[chrisrichardson]

I don't think this is an issue:

from dolfinx.mesh import create_box, CellType
from mpi4py import MPI

mesh = create_box(MPI.COMM_WORLD, [[0, 0, 0], [1, 1, 1]], [1, 1, 1], CellType.prism)

facets = mesh.topology.entity_types[2]

for j in range(2):
    mesh.topology.create_connectivity(2, j)
    for i in range(2):
        print(f"Connectivity {facets[i]} -> {mesh.topology.entity_types[j][0]}")
        f_to_v = mesh.topology.connectivity((2, i), (j, 0))
        for k in range(f_to_v.num_nodes):
            print(f_to_v.links(k))

should produce the correct (I think) output:

Connectivity CellType.quadrilateral -> CellType.point
[0 1 3 4]
[0 2 3 5]
[1 2 4 5]
[1 4 6 7]
[2 5 6 7]
Connectivity CellType.triangle -> CellType.point
[0 1 2]
[1 2 6]
[3 4 5]
[4 5 7]
Connectivity CellType.quadrilateral -> CellType.interval
[0 2 4 8]
[1 2 6 9]
[ 3  4  6 10]
[ 4  5 11 13]
[ 6  7 12 13]
Connectivity CellType.triangle -> CellType.interval
[3 1 0]
[7 5 3]
[10  9  8]
[12 11 10]

[schnellerhase]

Thanks, this was just incorrect usage of the interface. Previously this did not raise. With the changes of #3637 the initial example code also raises an assertion of the incorrect usage. Closing.