[petsc-dev] TS Terminology

[Matthew Knepley]

On Sat, Oct 21, 2017 at 9:28 AM, Jed Brown <jed at jedbrown.org> wrote:

> Matthew Knepley <knepley at gmail.com> writes:
>
> > On Fri, Oct 20, 2017 at 4:21 PM, Jed Brown <jed at jedbrown.org> wrote:
> >
> >> Matthew Knepley <knepley at gmail.com> writes:
> >>
> >> >> Note that TSComputeIFunction is very much like SNESComputeFunction,
> >> >> which includes
> >> >>
> >> >>   if (snes->vec_rhs) {
> >> >>     ierr = VecAXPY(y,-1.0,snes->vec_rhs);CHKERRQ(ierr);
> >> >>   }
> >> >>
> >> >> Why haven't you complained about that?
> >> >>
> >> >
> >> > Good point. I did not notice. This came up because the initialization
> >> > of input vectors is inconsistent between TSComputeIFunction() and
> >> > TSComputeIFunctionLocal(). The former does not zero the output vec,
> >> > but the later does.
> >>
> >> The latter function doesn't exist so maybe you mean
> >> TSComputeIFunction_DMDA with ADD_VALUES?  That's because the DMDA needs
> >> it when using ADD_VALUES, just like SNESComputeFunction_DMDA.  When
> >> using INSERT_VALUES, the user is responsible for setting every entry.
> >> Is any of this different from SNES?
> >>
> >
> > No I mean TSComputeIFunction_DMLocal().
>
> That's just some code you wrote for finite elements when you hard-coded
> it for ADD_VALUES.
>
>   ierr = DMLocalToGlobalBegin(dm, locF, ADD_VALUES, F);CHKERRQ(ierr);
>   ierr = DMLocalToGlobalEnd(dm, locF, ADD_VALUES, F);CHKERRQ(ierr);
>
> It's analogous to what TSComputeIFunction_DMDA does when you set
> ADD_VALUES.  Note that with INSERT_VALUES, as is typically used for FD
> and FV, you can assemble directly into the global vector
>
> > So if you use DMTSSetIFunction() you get different initialization
> > behavior than if you use DMTSSetIFunctionLocal().  This is what Brad
> > was complaining about originally.
>
> Maybe you should document your finite element interfaces better.
>

I think the fair statement would be that it is not documented either way.

   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.caam.rice.edu/~mk51/>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20171021/1645847f/attachment.html>