On Tue, Sep 10, 2013 at 2:48 PM, sang pham van <[email protected]> wrote:
> Hi Matt, > > Is it true that the option -snes_linesearch_type basic will make SNES run > with the pure Newton method (without line search nor true region)? > Yes. Matt > Thank you. > Sang > > > On Wed, Jun 5, 2013 at 1:04 PM, Matthew Knepley <[email protected]> wrote: > >> On Wed, Jun 5, 2013 at 12:33 PM, Gaurish Telang <[email protected]>wrote: >> >>> I am trying to solve a non-linear system with PETSs's SNES solvers. >>> >>> To run my code, I am using the following options for snes set through >>> the command-line, >>> seen below. >>> >>> mpirun -np 1 ./Testvector \ >>> -fBus $1/Bus.mat \ >>> -fYm $1/Ym.mat \ >>> -ft $1/t.mat \ >>> -flinedata $1/linedata.mat \ >>> -nox \ >>> -snes_atol 1.e-5\ >>> -snes_stol 1.e-6 \ >>> -snes_rtol 1.e-12 \ >>> -snes_max_it 100 \ >>> -snes_max_linear_solve_fail 100 \ >>> -snes_converged_reason \ >>> -ksp_type preonly \ >>> -pc_type lu \ >>> -pc_factor_mat_solver_package superlu_dist \ >>> -snes_monitor \ >>> > result_superLU_dist.tmp 2>&1; >>> >>> >>> After feeding my data, I get the following output >>> 0 SNES Function norm 2.438306296478e+02 >>> 1 SNES Function norm 1.679437793666e+02 >>> 2 SNES Function norm 1.493618467597e+02 >>> 3 SNES Function norm 4.622194635741e+01 >>> 4 SNES Function norm 4.195017632984e+01 >>> Nonlinear solve did not converge due to DIVERGED_LINE_SEARCH iterations 4 >>> >>> As you can see the the SNES function norm is *decreasing*, which >>> indicates it is probably converging slowly to the actual solution. However >>> after just 4 iterations, it stops and indicates non-convergence, even >>> though my -snes_max_it = 100 as shown above. >>> >>> Is there a way to tell PETSc to continue its SNES iterations? Maybe some >>> there are some >>> default parameters which have to be changed? >>> >> >> You can try -snes_max_fail <num> or maybe -snes_linesearch_type basic. >> >> Matt >> >> >>> Thank you >>> >>> Gaurish >>> >> >> >> >> -- >> 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 >> > > -- 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
