[petsc-dev] Non-scalable matrix operations

[Jed Brown]

On Fri, Dec 23, 2011 at 12:19, Mark F. Adams <mark.adams at columbia.edu>wrote:

> Eisenstat is not computing with zero data if there is no initial guess,
> right?  I'm not sure I understand you here.
>

I'm thinking of, e.g. third order Cheby preconditioned by GS.


>
> I know the theory doesn't argue for it, but G-S with Cheby sometimes wins
> over everything else I've tried.
>
>
> People damp G-S for convection etc, which is what Cheb/GS does.  Do you do
> this for SPD systems?
>

No, I was doing it for the thermo/lid-driven cavity, for example.


>
> Is there any hope of doing nonlinear G-S where the user can provide
> something moderately simple?
>
>
> Nonlinear should be very simple actually.  Just replace my hacks into
> (MPI)AIJ matrices with your own operator.
>

Sure, but what does the user need to provide? How much code can we reuse
between the matrix-based implementation and the nonlinear implementation?
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