systems_of_equations_ex4 % mpirun -np 2 ./example-opt works flawlessly. My configuration is using PETSc and i highly recommend you install PETSc and reconfigure/recompile your libmesh installation.
On Tue, Sep 15, 2015 at 11:55 AM, Stephan Herb <inf74...@stud.uni-stuttgart.de> wrote: > Thanks Julian for addressing this problem; although I changed it to the > correct version nothing changed (well, now only the displacements for > the local nodes gets printed instead of all nodes^^). > I came up with another issue: If you run the example code 4 of "Systems > of Equations" (Linear Elastic Cantilever) with the command "mpirun -np 2 > ./example-opt" one gets "-nan" as solutions. When you export it for > example as vtu files theone part cannot be loaded in a visualization > program like paraview and the other part can be loaded but only contains > zeros... > So I might have no problem with my code, but perhaps with my libmesh > configuration, or I need additional starting parameters, or ... don't > know. Any suggestions? Someone has tested the examples with multiple > processes and got right results? > > regards, > Stephan > > Am 15.09.2015 um 09:54 schrieb Julian Andrej: >> Hi, >> >> maybe there is a problem with your iterator, as you are using >> >> MeshBase::const_node_iterator no = mesh.nodes_begin(); >> >> so it tries to get all nodes (from every processor), you could try >> >> MeshBase::const_node_iterator no = mesh.local_nodes_begin(); >> >> to fetch just the local nodes. Do you know if your solution (in sense >> of solving) is a problem or gathering the solution onto one machine? >> >> regards >> Julian >> >> >> On Tue, Sep 15, 2015 at 9:28 AM, Stephan Herb >> <inf74...@stud.uni-stuttgart.de> wrote: >>> Hi, >>> >>> my code is the main part of my Master Thesis, so I need to talk with my >>> professor about sharing it with the libmesh community. >>> I uploaded my config.log here (http://pastebin.com/X3whQhLs) so you can >>> check it. As far as I know I don't have PETSc installed/configured yet >>> but there should be no problem to make up for this if this solves my >>> problem. >>> I also uploaded a shortened version of my code such that you can see >>> what libmesh functions I'm using. Here is the link: >>> http://pastebin.com/L9QrYkLQ >>> Everything I removed from the code are computations of local matrix >>> entries, copying those entries into 'Ke' and 'Fe' and accessing the >>> pointers to the element's nodes (for their coordinates); so nothing that >>> could crash the program or interfere with the system solving step... >>> >>> Bye, >>> Stephan Herb >>> >>> Am 14.09.2015 um 17:34 schrieb John Peterson: >>>> >>>> On Mon, Sep 14, 2015 at 3:46 AM, Stephan Herb >>>> <inf74...@stud.uni-stuttgart.de >>>> <mailto:inf74...@stud.uni-stuttgart.de>> wrote: >>>> >>>> Hello, >>>> >>>> I wrote a code to compute displacements and drilling moments for flat >>>> shell elements with FEM. It imports a mesh file (xda or msh), >>>> assembles >>>> the system matrix and RHS, solves the system and exports the >>>> results as >>>> vtk files. >>>> When I run my program with one processor it all works fine and the >>>> displacements are correct. The problem occurs with more than one >>>> processor. >>>> Simple example: Plane mesh (e.g. 8x8 quadrilaterals). Left edge is >>>> clamped, the force is applied at the right edge and only at this edge. >>>> If I run this example with e.g. 2 processors the partitioning cut >>>> halves >>>> the mesh in a left and a right part. The result looks as follows: The >>>> left part has no displacement at all, while the right part has a huge >>>> displacement. >>>> >>>> >>>> So you implemented a new type of shell finite element in libmesh? It >>>> would be great if this is something you could share with us in a >>>> branch on GitHub... >>>> >>>> >>>> I studied your example codes and couldn't see any special code >>>> fragments >>>> that is needed for a parallelized version of the code, so I thought: >>>> 'Hey, libmesh seems to handle the parallelization internally - that's >>>> great!'. But when I look at my results; in my opinion every processor >>>> solves its own partial system with its own boundary condition, mesh >>>> nodes and RHS and produces its own solution - so no communication or >>>> exchange between the processes at all... >>>> >>>> >>>> Are you using PETSc? Please send me (or share on google docs) your >>>> config.log file so I can take a look at your system's configuration. >>>> >>>> >>>> Now to my questions: Do I need additional configurations in my code to >>>> make it work (at the LinearImplicitSystem, the mesh, the system >>>> matrix, >>>> etc.)? Additional MPI code to exchange values/vectors/matrices by my >>>> own? Libmesh seems to use MPI communication extensively internally and >>>> it's difficult for me right now to see where the problem is. >>>> Perhaps you >>>> can give me a hint to be back on track soon. >>>> >>>> >>>> You shouldn't need to do anything too special. One big thing is to >>>> make sure you use "active_local" element iterators instead of "active" >>>> ones in your assembly routine if you are writing non-FEMSystem style >>>> libmesh code. >>>> >>> ------------------------------------------------------------------------------ >>> _______________________________________________ >>> Libmesh-users mailing list >>> Libmesh-users@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/libmesh-users > > > ------------------------------------------------------------------------------ > _______________________________________________ > Libmesh-users mailing list > Libmesh-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/libmesh-users ------------------------------------------------------------------------------ _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
