This is almost definitely not a libMesh problem. It sounds like an uninitialized variable. I recommend running your application using valgrind ( http://valgrind.org ) . Use a debug (dbg) build of your application and valgrind will point you right to the problem.
Derek On Thu, Jan 2, 2014 at 7:30 PM, Dafang Wang <[email protected]> wrote: > Hi, > > My libmesh progam, which uses SNES to solve a nonlinear equation, had > different > convergence behavior when running on a linux desktop and on a cluster > machine. > > All other running conditions were double checked to be identical: It was > the same program > running as a single thread on both machines. Both machines were using > Libmesh 0.9.2.2. > > My program was solving a simple elastic model with good numerical/physical > behavior. (The > model consists of a 5*5*5 cubic mesh with a total of ~600 degress of > freedom.) For the > nonlinear solve, I was using the Newton method and line search (the > default settings in > Petsc SNES). > > The Newton method took 5 iterations to converge on my desktop (Ubutun > 12.04), whereas it > took 114 iterations to converge on the cluster. Moreover, both machines > generated > identical results in the first 2 Newton iterations, then they diverged > from the 3rd > iteration. > > I am wondering if such difference is common for Libmesh/Petsc programs > running on > different machines. Does anyone have similar experience of running > programs on different > clusters? > > Thanks, > Dafang > -- > Dafang Wang, Ph.D. > Postdoctoral Fellow > Institute of Computational Medicine > Hackerman Hall, Room 218 > Johns Hopkins University, Baltimore, 21218 > http://lagniappe.icm.jhu.edu/~dwang/ > > > ------------------------------------------------------------------------------ > Rapidly troubleshoot problems before they affect your business. Most IT > organizations don't have a clear picture of how application performance > affects their revenue. With AppDynamics, you get 100% visibility into your > Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics > Pro! > http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk > _______________________________________________ > Libmesh-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/libmesh-users > ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
