On Thu, Nov 10, 2011 at 11:07, Konstantinos Kontzialis < ckontzialis at lycos.com> wrote:
> 1. I use the conservative variables. > > 2. No limiter. > > 3. Boundary conditions are weakly imposed (to solve the riemann problem). > > 4. mat_fd_type ds is worse for the current case > It sounds like your system is poorly scaled. If you were consistent about using PetscScalar in your code, then you can configure --with-precision=__float128 and try that. It should remove the differencing errors. It is very important to scale the system carefully when using coloring or matrix-free finite differencing. It's a waste of time to dwell on the other issues until you know that you have an accurate Jacobian. > 5. sub_pc_type lu did a better work but not to a satisfactory level > In terms of time or iteration count? This test is for iteration count. > > 6. MATCOLORINGSL is used. > > For the preconditioner I need to do some changes. > > Please help me first to understand the coloring types in order to choose > the best one (any web pages, links etc.?). > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20111110/c81d47a8/attachment.htm>
