On Fri, Mar 15, 2013 at 1:15 PM, John Peterson <[email protected]> wrote: > On Fri, Mar 15, 2013 at 1:03 PM, Roy Stogner <[email protected]> wrote: >> >> On Fri, 15 Mar 2013, Jens Lohne Eftang wrote: >> >>> On 03/15/2013 02:01 PM, Roy Stogner wrote: >>>> >>>> I'd start by turning on PETSc's monitor flags ('-ksp_monitor' etc?). >>>> Endless residual reevaluations suggests to me that the initial >>>> linear solve converged poorly and didn't give you a descent direction, >>>> and a subsequent line search is failing to find a reduced nonlinear >>>> residual. >>> It seems to me that the residual gets assembled after the solver has >>> converged, for some reason. >> >> Yes: After you take a Newton step, the Newton solver typically wants >> to make sure that that step gave you a (nonlinear) residual reduction, >> and to see whether that new residual meets your tolerances so that the >> Newton iteration can claim convergence and exit. >> >> If you got a good linear solve (so the new proposed solution is a >> descent direction) but the next nonlinear residual is lousy, then >> typically the next operation is a line search, which does a whole >> bunch more residual evaluations at points in between the solution at >> the previous nonlinear solve and the failed proposed next step. >> >> But it looks like you're getting a good linear solve yet not getting a >> good line search result. Is it possible your residual and Jacobian >> aren't consistent? > > Petsc 3.3? You can also try "-snes_linesearch_type basic" to turn > linesearch off completely > > Prior to 3.3 it was "-snes_ls basic"
Wait, nevermind, you said FEMSystem, which is base on ImplicitSystem, sorry. Those options won't do anything. -- John ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
