Dear Wolfgang, On Thursday, October 20, 2016 at 9:48:55 PM UTC-5, Wolfgang Bangerth wrote: > > What is the norm of the first right hand side? You now set the tolerance > in > the first iteration to a fixed value of 1e-16, but how does this compare to > the previous value of 1e-12*system_rhs.l2_norm()? >
The system_rhs.l2_norm() before the first call to CGSolverat in the zero time step was 1.82492e-09, so that the 1e-12*system_rhs.l2_norm() became in the order of 1e-21 by which CGSOlver didn't converge. > > That still seems wrong to me. As I mentioned in a previous email, you > ought to > make sure that the matrix you build is the matrix you *want* to build. > I was wondering how to make sure the matrix I built is what I meant. In addition, Bruno already mentioned sometimes PreconditionerAMG has problem with non-positive definite System_matrices. Thanks -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
