[petsc-users] snes options for rough solution

[Matthew Knepley]

On Mon, Dec 12, 2016 at 12:56 AM, Praveen C <cpraveen at gmail.com> wrote:

> Increasing number of snes iterations, I get convergence.
>
> So it is a problem of initial guess being too far from the solution of the
> nonlinear equation.
>
> Solution can be seen here
>
> https://github.com/cpraveen/fenics/blob/master/1d/cosmic_
> ray/cosmic_ray.ipynb
>
> Green curve is solution after two time steps.
>
> It took about 100 snes iterations in first time step and about 50 in
> second time step.
>
> I use exact Jacobian and direct LU solve.
>

I do not believe its the correct Jacobian. Did you test it as I asked? Also
run with

  -snes_monitor -ksp_monitor_true_residual -snes_view -snes_converged_reason

and then

  -snes_fd

and send all the output

   Matt


> Thanks
> praveen
>



-- 
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
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