Hi everyone, Thank you all for your incredible guides. It seems that I've been choosing wrong solver for my problem. Since my problem has some sort of instability in its nature, although my system_matrix is symmetric, it is not necessarily positive definite. So I have two questions: First, Is there any function in Dealii or Petsc to compute the determinant of system_matrix. I have used a determinant function for 3*3 matrices and it doesn't work for higher dimensions. Second, which solver and preconditioner can be used for symmetric but non-positive definite system_matrix.
Thanks On Tuesday, October 18, 2016 at 9:49:03 AM UTC-5, Wolfgang Bangerth wrote: > > > which solvers do you think I can examin and see if they can be used > > instead of SolverCG? > > That's the wrong question. If you know that the matrix you have *should > be* > symmetric and positive definite, but the CG solver does not converge, then > you > need to debug why the matrix *is not* s.p.d. Using a different solver > might > allow you to solve the linear system, but since the linear system is > apparently not the correct one, the solution will also not be correct. > > Best > W. > > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: bang...@colostate.edu > <javascript:> > www: http://www.math.colostate.edu/~bangerth/ > > -- 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.
