[petsc-users] [EXT]Re: Is using PETSc appropriate for this problem

[Matthew Knepley]

On Thu, Sep 17, 2020 at 12:23 AM Jed Brown <jed at jedbrown.org> wrote:

> Alexander B Prescott <alexprescott at email.arizona.edu> writes:
>
> >>      Are the problems of varying nonlinearity, that is will some
> converge
> >> with say a couple of Newton iterations while others require more, say 8
> or
> >> more Newton steps?
> >>
> > The nonlinearity should be pretty similar, the problem setup is the same
> at
> > every node but the global domain needs to be traversed in a specific
> order.
>
>
> It sounds like you may have a Newton solver now for each individual
> problem?  If so, could you make a histogram of number of iterations
> necessary to solve?  Does it have a long tail or does every problem take 3
> and 4 iterations (for example).
>
> If there is no long tail, then you can batch.  If there is a long tail,
> you really want a solver that does one problem at a time, or a more dynamic
> system that checks which have completed and shrinks the active problem
> down.  (That complexity has a development and execution time cost.)
>

He cannot batch if the solves are sequential, as he says above.

   Matt

-- 
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

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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