Matt, Thanks for your reply. It DOES make no sense for this problem. But I am not clear about the 'preonly' option. Which solver is used in preonly? I wonder if 'preonly' is suitable for large scale problem such as 400,000,000 unknowns. So I tried 'gmres' option and found these error messages.
Could you give me some suggestions? Thanks. Wenbo On Mon, Oct 2, 2017 at 12:34 AM, Matthew Knepley <knep...@gmail.com> wrote: > On Sun, Oct 1, 2017 at 6:49 AM, Wenbo Zhao <zhaowenbo.n...@gmail.com> > wrote: > >> Hi, >> >> I met some questions when I use PETSC/SLEPC to solve two-group neutron >> diffusion equations with finite difference method. The grid is 3*3*3, when >> DOF on each points is 2. So the matrix size is 54*54. >> It is generalized eigenvalue problem Ax=\lamda Bx, where B is diagonally >> dominant matrix but not symmetry. >> EPS is set as below, >> ierr = EPSSetProblemType(eps,EPS_GNHEP);CHKERRQ(ierr);¬ >> ierr = EPSSetWhichEigenpairs(eps,EPS_LARGEST_REAL);CHKERRQ(ierr);¬ >> >> Krylovschur is used as eps sovler. GAMG is used as PC. >> I tried agg_nsmooths and mg_coarse_ksp_type. Only non-smooths and preonly >> is OK. >> > > Why are you setting the coarse solver. This makes no sense. > > Thanks, > > Matt > > >> >> Test 1 >> $ make NCORE=1 runkr_nonsmooth >> mpirun -n 1 ./step-41 \ >> -st_ksp_type gmres \ >> -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths 0 \ >> -st_ksp_view -mata AMAT.dat -matb BMAT.dat \ >> -st_mg_coarse_ksp_type preonly -st_mg_coarse_ksp_monitor \ >> -eps_nev 1 -eps_ncv 10 -eps_monitor -log_view > log_nonsmooth 2>&1 >> >> Test 2 >> $ make NCORE=1 runkr_smooth >> mpirun -n 1 ./step-41 \ >> -st_ksp_type gmres \ >> -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths 1 \ >> -st_ksp_view -mata AMAT.dat -matb BMAT.dat \ >> -st_mg_coarse_ksp_type preonly -st_mg_coarse_ksp_monitor \ >> -eps_nev 1 -eps_ncv 10 -eps_monitor -log_view > log_smooth 2>&1 >> makefile:43: recipe for target 'runkr_smooth' failed >> make: *** [runkr_smooth] Error 91 >> >> Test 3 >> $ make NCORE=1 runkr_gmres >> mpirun -n 1 ./step-41 \ >> -st_ksp_type gmres \ >> -st_pc_type gamg -st_pc_gamg_type agg -st_pc_gamg_agg_nsmooths 0 \ >> -st_ksp_view -mata AMAT.dat -matb BMAT.dat \ >> -st_mg_coarse_ksp_type gmres -st_mg_coarse_ksp_monitor >> -st_mg_coarse_ksp_rtol 1.0e-6 \ >> -eps_nev 1 -eps_ncv 10 -eps_monitor -log_view > log_gmres 2>&1 >> makefile:59: recipe for target 'runkr_gmres' failed >> make: *** [runkr_gmres] Error 91 >> >> Log files were attched. >> The matrix file were also attched as AMAT.dat and BMAT.dat. >> >> Is it correct? Or something wrong with my code or commad-line? >> >> Thanks! >> >> Wenbo >> > > > > -- > 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/> >