On Mon, 2 Jun 2008, Derek Gaston wrote: > On Jun 2, 2008, at 9:45 AM, Roy Stogner wrote: > > What advantages does FEMSystem have over using Ben's > NonlinearImplicit system stuff using SNES? I've used both, but I > don't really see the difference.
For you, since the numerical jacobians aren't useful right now, one of the biggest advantages is gone. But having the time integration factored out is nice for transient problems, and the interior_, side_, etc. helper methods are nice for nonlinear problems. But the biggest remaining benefits are still "to be written", I think. Threaded assembly (without having to write your own weird TBB code) should be a nice feature, even if we'll have to go through an API change to get there. And there are some other niceties (bubble-function based physics-dependent error estimators, for example) that can really only be implemented if the library can request residuals of one element at a time. > For us, we're using the NonlinearImplicit system because we hope to fill out > the Trilinos interfaces at some point and use NOX instead... Is something wrong with the FEMSystem->SNES interface? I admit that I basically gave up on PetscDiffSolver when it turned out that my own quasi-Newton code was faster on my apps, but there's at least a place there to start. If you're doing matrix-free work, the fact that DiffSystem currently inherits from ImplicitSystem may be a stumbling block, but NonlinearImplicitSystem has the same problem. --- Roy ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
