Re: [deal.II] Pure Neumann BCs in mixed form

2019-03-26 Thread Wolfgang Bangerth
On 3/26/19 5:29 AM, Konrad wrote: > Issue resolved. I used the wrong sparsity pattern. That was just a typo in > the > code. Sorry for having bothered you with this but anyway: Well, glad you found the problem. Also, doh for deriving the compatibility condition -- that was too simply for me no

Re: [deal.II] Pure Neumann BCs in mixed form

2019-03-26 Thread Konrad
Issue resolved. I used the wrong sparsity pattern. That was just a typo in the code. Sorry for having bothered you with this but anyway: Many thanks, Konrad -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii

Re: [deal.II] Pure Neumann BCs in mixed form

2019-03-26 Thread Konrad
Hi Wolfgang, > Precisely what do you see? >> > > Chaotic distribution of values in the solution several orders of > magnitudes higher than what I expect. > > >> I haven't heard of this, but that doesn't mean anything. How do you >> actually derive the compatibility condition in the mixed ca

Re: [deal.II] Pure Neumann BCs in mixed form

2019-03-25 Thread Wolfgang Bangerth
On 3/23/19 7:23 AM, Konrad wrote: > > I am trying to solve a simple elliptic problem (imagine some sort of a > simple Laplace problem for now) with pure Neumann BCs, say -\Delta u = > f, n\grad u = g. Now theory tells me that the volume average over f must > be the same as the boundary average

[deal.II] Pure Neumann BCs in mixed form

2019-03-23 Thread Konrad
Hi all, I am encountered a weird thing (bug?) and I am having trouble to understand it. Maybe someone has an idea: I am trying to solve a simple elliptic problem (imagine some sort of a simple Laplace problem for now) with pure Neumann BCs, say -\Delta u = f, n\grad u = g. Now theory tells me