On Sun, Jul 19, 2015 at 9:45 AM, Khai Pham <[email protected]> wrote:
> Dear Petsc-Users, > > The SNES only converges for a small problem. I did the jacobian check. The > result is sensitive to the choice of differencing parameter. > This looks like you probably have the correct Jacobian, but the problem is very sensitive. Then convergence might be hard as you scale up because you have a bad initial guess. Its impossible to say anything else without knowing more about your problem. Matt > With the option "-snes_type test": > > "Norm of matrix ratio 4.11569e-09 difference 7.64426e-07 (user-defined > state) > Norm of matrix ratio 2.05846e-08 difference 3.89655e-06 (constant state > -1.0) > Norm of matrix ratio 5.77446e-09 difference 1.09307e-06 (constant state > 1.0)" > > with the option "-snes_type test -mat_fd_type ds" : > > "Norm of matrix ratio 1.05213e-07 difference 1.95418e-05 (user-defined > state) > Norm of matrix ratio 2.51463e-07 difference 4.76004e-05 (constant state > -1.0) > Norm of matrix ratio 2.81081e-08 difference 5.32071e-06 (constant state > 1.0)". > > Could you give me any hint where should I check for the error? > > Khai > > > -- 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
