[petsc-dev] perhaps where the custom adapativity perversity began

[Lisandro Dalcin]

On 30 April 2017 at 23:34, Jed Brown <jed at jedbrown.org> wrote:
>
> One reliable, if somewhat expensive, option would be to use
> extrapolation similar to TSARKIMEX1BEE.

Somewhat expensive :-) ?

>  If this feels like reinventing
> a wheel using stone tools, it is; we could just add a TSARKIMEX tableau
> for Theta with extrapolation.
>

Oh, I'm not going to touch TSARKIMEX until the TSClone() business gets
refactored/cleaned up.

But in general, I'm not opposed to your suggestion.

> Since Theta is supposed to be an implementation that newcomers use as an
> example to learn how TS works, we should try to keep it as clean/simple
> as possible.

Too late, my friend:

* THETA is backing the other two methods BEULER and CN.
* We have the DM subdomain/restrict hooks stuff.
* We have the adjoint stuff.
* And finally, I already added time adaptivity in last release to
contribute some extra entropy.

so I think THETA abandoned simplicity in favor of features long time ago.

>  I think it would also be okay to have no error estimator

Why? Having support for some sort of adaptivity, that is not default,
and based on a cheap estimator seems like a win-win for me... IMHO,
practicality beats purity in this case.

> -- it seems likely that user implementations may not have an error
> estimator (though maybe they should think about it up-front).

What did you mean? I'm not following you in these lasts comments...


-- 
Lisandro Dalcin
============
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