[dune-pdelab] Off main-diagonal Dirchlet conditions

[Andreas Lauser]

Hi pdelabers,

Now I am able to use mixed boundary conditions with PowerGridFunctionSpace 
which is great! The next thing which would be nice to have is a way to specify 
which equation determines which dirichlet condition. If I my understanding of 
the constraints framework in PDELab is correct I do not see a way to do this.

Example:

For two-dimensional P1-Elements, the LocalPowerGridFunctionSpace for two 
equations looks like this:

(root)
|
|--- (local finite element for equation 0)
|     |-> coefficient index for vertex 0
|     |-> coefficient index for vertex 1
|     \-> coefficient index for vertex 2
\--- (local finite element for equation 1)
      |-> coefficient index for vertex 0
      |-> coefficient index for vertex 1
      \-> coefficient index for vertex 2

If I understood everything correctly, constraints are defined by inserting the 
weights of number of DOFs to the constraints tranformation. Also the weights 
of the DOFs are specified by their index in the local finite element if I'm 
not mistaken.

What I would like to have is a way to define constraints depending on the 
solution of a different finite element, for example using equation 1 to 
specify the dirichlet value for primary variable 0 on the the first vertex. I 
guess this would require to store some global DOF indices in the constraints 
transformation. How can I do this? Quite likely I'm just too stupid to see 
some obvious solution...

Regards
  Andreas

-- 
Andreas Lauser
Lehrstuhl für Hydromechanik und Hydrosystemmodellierung
Universität Stuttgart - Institut für Wasserbau
Pfaffenwaldring 61
D-70569 Stuttgart
Tel: (+49) 0711/ 685-64719
Fax: (+49) 0711/ 685-60430
e-mail: andreas.lauser at iws.uni-stuttgart.de