> thanks for your reply. I also did think that the order might be a > problem, so I applied the periodic boundaries first as I wanted the > Dirichlet conditions to "win". > > I now tried also your decision using two constraints and merging them > and set the dirichlet ones as the winner. But didn't hasn't had any > effect. I got the same matrix and rhs and the same result. > I than tried it also the other way round, which again gave the same > behavior. > > So, something else must be the problem. In addition I found out the > number of dofs common to both constraints and explicitly skipped setting > periodic constraints to them. Still the same... > > Btw, this behavior only occurs for one of the two components.
The way to debug these kinds of problems is to use, say, a 2x2 mesh for which you can compute the system matrix (without constraints) by hand, print it to the screen and verify that it's correct. Then also print to screen all the constraints in your ConstraintMatrix and see whether they make any sense. I'm fairly confident that the ConstraintMatrix does the right thing if the constraints stored in it are correct, so if your solution is wrong then it's either the assembly of the matrix or rhs, or that the constraints are filled the wrong way. You should be able to find out which it is for a small enough problem. Best W. ------------------------------------------------------------------------- Wolfgang Bangerth email: [email protected] www: http://www.math.tamu.edu/~bangerth/ _______________________________________________ dealii mailing list http://poisson.dealii.org/mailman/listinfo/dealii
