[dune-pdelab] Accessing solution vector for MPFA

[Shubhangi Gupta]

Dear All,

I am trying to implement a Multi-Point-Flux-Approximation (MPFA) method 
in DUNE PDELab.

I pass the current solution vector (u) by a pointer to the 
localoperator, from where I call the MPFA-method to calculate the flux 
over the edge.
In the same step, I give the solution vector (u) to the stationary 
problem solver by slp.apply(u).
However, when I solve the problem, the values of u which are taken by 
MPFA-method differ from the solution vector which is passed to the 
localoperator by calling alpha_skeleton.
Because of this, the mpfa fails to converge even though it uses the 
values from the pointer to the solution vector.

My question is:
Why is the value of u from the pointer to the solution vector different 
from the local solution in the alpha_skeleton?
Also, which vector is passed to the alpha skeleton and is it possible to 
access the whole solution vector from alpha skeleton somehow?


Thanks in advance,
Best regards,
Shubhangi