[petsc-users] ODE solving

[Matthew Knepley]

On Thu, Oct 21, 2010 at 5:01 PM, Jed Brown <jed at 59a2.org> wrote:

> On Thu, Oct 21, 2010 at 23:56, Matthew Knepley <knepley at gmail.com> wrote:
> > You SNES is not converging. You solve 163 systems, but do 4300 function
> > evaluations.
>
> That is because the Jacobian is assembled using coloring.
>

With that many colors, it seems like you should sit down and work out the
Jacobian.

   Matt


> Sundials is probably doing fewer steps than BEuler for this problem,
> and it's also lagging the preconditioner and just using matrix-free
> differencing to define the Krylov operator.  These options are not
> default with PETSc's TS implementations.
>
> Jed
>



-- 
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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