Hi Matt, Thanks for your response. You were right: the right hand side matrix has had some 'nan's which caused the solver to return error. Strangely this does not happen when #cpus are less than 4! I am going to search for the source of that.
Best, Mohammad On Wed, Jan 10, 2018 at 5:04 PM, Matthew Knepley <[email protected]> wrote: > On Wed, Jan 10, 2018 at 4:41 PM, Mohammad R. Gohardoust < > [email protected]> wrote: > >> Hi, >> >> I hope you are doing well. I am Mohammad, a PhD student of environmental >> sciences at the University of Arizona. >> >> I do appreciate any help that can shed some light on the issue I have: >> recently I have added a feature to an existing parallel code called >> 'parswms' which solves water and solute transport in soils. The code uses >> MPI and parmetis for the parallelization purposes and petsc package >> (KSPSolve) for solving linear systems. I have it installed on the UofA >> HPC : the issue is that it works well if the number of CPUs are up to 4! >> but when I add to this number the numerical linear solver (here it is >> 'KSPCGS') stops with the error of 'KSP_DIVERGED_NANORINF'. >> >> Would you mind please giving me some hints, suggestions or resources in >> this regard? >> > > It sounds like you might have a problem in matrix assembly. However, first > use -pc_type gmres instead since > it has nicer numerical behavior (I believe). > > Thanks, > > Matt > > >> Best Regards, >> Mohammad >> >> >> >> > > > -- > What most experimenters take for granted before they begin their > experiments is infinitely more interesting than any results to which their > experiments lead. > -- Norbert Wiener > > https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/> >
