SubDomain on_boundary detection for vertices and edges

[Francesco Ballarin]

Dear FEniCS community,

suppose I have a 2D domain and want to define a VertexFunction equal to 1 for vertices on the boundary. I thought that using the on_boundary flag in SubDomain::inside() would do this task in SubDomain::mark(), but it seems that the flag only applies to facets.

Is there a reason for which this flag is only available to facets? If not, is there interest in extending the availability of this flag also to vertices and edges? If so, I have a simple patch to SubDomain::mark() (that marks as on boundary if at least one connected facet is on boundary) and I can open a pull request to further discuss it.

Thanks, best regards, Francesco Ballarin

[Jan Blechta]

I'd suggest to open a pull request for the sake of discussion.

[Francesco Ballarin]

Closed by PR 356