On Mon, May 4, 2015 at 5:41 PM, Reza Yaghmaie <[email protected]> wrote:
> > Dear Matt, > > Actually the initial jacobian was identity. Regular SNES converges in 48 > iterations, GMRES in 19, NCG in 67,... > Do you think SNESQN with the basiclineseach was the problem for divergence? > If I use SNESQN by default should not it converge with initial identity > jacobian? > Do you mean that you used an initial guess of the identity, or that the Actual Jacobian was the identity at your initial guess? Matt > Best regards, > Reza > > > > > On Monday, May 4, 2015, Matthew Knepley <[email protected]> wrote: > >> On Mon, May 4, 2015 at 2:11 PM, Reza Yaghmaie <[email protected]> >> wrote: >> >>> >>> Dear PETSC representatives, >>> >>> I am solving a nonlinear problem with SNESNGMRES and it converges faster >>> with less iterations compared to otehr SNES methods. Any idea why that is >>> the case? >>> >> >> It is impossible to tell with this information. >> >> >>> Also SNESQN diverges quickly. I tried to use SNESLINESEARCHBASIC for >>> the linesearch option and nothing changes. >>> >> >> This can happen, especially if your matrix is far from the identity. >> >> >>> I presume it is using the default SNESQN method. Btw, there are three >>> options for QN, as "SNES_QN_LBFGS, SNES_QN_BROYDEN, SNES_QN_BADBROYEN" >>> in teh manual. I tried to associate them with SNES however it seems these >>> hyphened names don't work there. What am I missing? >>> >> >> -snes_qn_scale_type <lbfgs,broyden,badbroyden> >> >> from >> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/SNES/SNESQNSetType.html >> >> Thanks, >> >> Matt >> >> Best regards, >>> Ray >>> >> >> >> >> -- >> 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
