Re: [Libmesh-devel] inhomogenous DOF constraints

[Boyce G. <gri...@ci...>]

On 12/2/10 8:03 PM, Boyce Griffith wrote:
> Hi, Folks --
>
> I'm trying to add support for inhomogeneous DOF constraints to DofMap. I
> think I am almost there --- if I add the constraints after calling
> init(), everything appears to work. These constraints are quite simple
> --- they are just inhomogeneous Dirichlet boundary conditions. I've
> verified that the work in the context of a modified version of ex4.
>
> If I add the constraints by setting user_constrain in the system, things
> break (specifically, the matrix is not properly constrained). I think
> that the problem is related to DofMap::process_constraints(). What is
> this method doing? I am having a little bit of trouble deciphering it...

Sorry to reply to myself, but I think that I realized what the problem 
was --- these DOFs are "constrained" to themselves, which was resulting 
in process_constraints() removing the constraint from the row of the 
constraint matrix altogether when trying to expand out recursive 
constraints...

-- Boyce