Lagrange multiplier for Dirichlet boundary condition

General Discussion
7

Dear @cmd @marchywka , thank you both for your previous help and I have made good process about using Lagrange multiplier to implement Dirichlet BC. However, there are problems when I try to parallelise my code.
It seems FreeFemm++ and ff-mpirun -n 1 … compile code differently. I found the fowllowing three operations are not allowed using ff-mpirun -n 1…, while it works well for FreeFem++

1. int[int] labs = [1];
    ThS = extract(ThG, label=labs);
2. matrix UAtemp = ua(Vh,Sh);
3. createMat(ThS, UU, Pk)

it seem createMat(ThS UU, Pk) does not work for a surface mesh ThS ? also it seems the second command is illegal if Vh and Sh are in two different FE spaces defined on two different meshes?

Can you please help me have a look? the sequential code works well.
stokes_lagrange_parallel.edp (2.2 KB)
stokes_lagrange.edp (1.5 KB)