[petsc-users] -ts_adapt_clip .5,1.25

[Mark Adams]

On Wed, Mar 4, 2020 at 4:03 PM Jed Brown <jed at jedbrown.org> wrote:

> See -ts_adapt_scale_solve_failed.  '


That's it. No C interface for this so no doc.


> The clip provides bounds on step
> shortening as a result of the error indicator, but a solve failing can
> be more severe.  The default clip allows more aggressive shortening, but
> I don't think we want clip to be a lower bound on solver-failure
> shortening.  And if you shorten and still fail, you want to be able to
> shorten more.
>

Not exactly sure what you are getting at here. I don't have a problem with
the default, I just couldn't find where to change it. My problem gets
smoother and is pretty simple and well behaved, so I don't need such an
aggressive response, I think. I don't have a problem with the default, it's
just that I'm trying to squeeze out some performance and I don't want it to
fall back so much.

Thanks,
Mark

 that the "clip" increase increment that I set (eg, 1.25), when aoos


>
> Mark Adams <mfadams at lbl.gov> writes:
>
> > I use -ts_adapt_clip .5,1.25, with -ts_type arkimex -ts_arkimex_type
> 1bee.
> > When SNES hits max_it (in the first stage), TS seems to reduce the time
> > step by 4x. I don't see where that 4x comes from and how to adjust it. Is
> > it in the "safety" stuff?
> > Thanks,
> > Mark
>
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