First of all, the code is not valid when you set X_MP to r_outer.
You are passing it in wrongly to your function:
as r_outer is interpreted as X_MP.
This should be:
mesh, subdomains, facet_tags = OneDimensionalSetup(n_elem, r_outer=r_outer)
However, irregardless, you are right the the integrals aren’t correct. This is due to me not implementing dS integrals as part of the integration kernels: dolfinx_mpc/cpp/assemble_matrix.cpp at main · jorgensd/dolfinx_mpc · GitHub
Feel free to open an issue in the Github repo, and I’ll see if I have time to implement it over christmas.