[deal.ii] setting dn u at the boundary when this is a dof

[Baerbel Janssen]

Dear deal.II experts,

I would like to set boundary values for the normal derivative. In the 
element I use this is a degree of freedom. So when I solve problems with 
homogeneous conditions there is no problem, but when solving with 
inhomogeneous conditions I get terrible results. I use the 
MatrixTools::apply_boundary_values function. Can someone explain what I am 
doing wrong?

Thanks in advance.

Cheers,
Bärbel_______________________________________________