On Wed, May 17, 2023 at 11:20 AM Berend van Wachem <berend.vanwac...@ovgu.de>
wrote:
> Dear Matt,
>
> Is there a way to 'redo' the DMLocalizeCoordinates() ? Or to undo it?
> Alternatively, can we make the calling of DMLocalizeCoordinates() in the
> DMPlexCreate...() routines optional?
>
> Otherwise, we would have to copy all arrays of coordinates from
> DMGetCoordinatesLocal() and DMGetCellCoordinatesLocal() before
> scaling them.
>
I am likely not being clear. I think all you have to do is the following:
DMGetCoordinatesLocal(dm, &xl);
VecScale(xl, scale);
DMSetCoordinatesLocal(dm, xl);
DMGetCellCoordinatesLocal(dm, &xl);
VecScale(xl, scale);
DMSetCellCoordinatesLocal(dm, xl);
Does this not work?
Thanks,
Matt
Best regards, Berend.
>
> On 5/17/23 16:35, Matthew Knepley wrote:
> > On Wed, May 17, 2023 at 10:21 AM Berend van Wachem <
> berend.vanwac...@ovgu.de <mailto:berend.vanwac...@ovgu.de>> wrote:
> >
> > Dear Matt,
> >
> > Thanks for getting back to me so quickly.
> >
> > If I scale each of the coordinates of the mesh (say, I want to cube
> each
> > co-ordinate), and I do this for both:
> >
> > DMGetCoordinatesLocal();
> > DMGetCellCoordinatesLocal();
> >
> > How do I know I am not cubing one coordinate multiple times?
> >
> >
> > Good question. Right now, the only connection between the two sets of
> coordinates is DMLocalizeCoordinates(). Since sometimes
> > people want to do non-trivial things to
> > coordinates, I prefer not to push in an API for "just" scaling, but I
> could be convinced
> > the other way.
> >
> > Thanks,
> >
> > Matt
> >
> > Thanks, Berend.
> >
> > On 5/17/23 16:10, Matthew Knepley wrote:
> > > On Wed, May 17, 2023 at 10:02 AM Berend van Wachem
> > > <berend.vanwac...@ovgu.de <mailto:berend.vanwac...@ovgu.de>
> <mailto:berend.vanwac...@ovgu.de
> > <mailto:berend.vanwac...@ovgu.de>>> wrote:
> > >
> > > Dear PETSc Team,
> > >
> > > We are using DMPlex, and we create a mesh using
> > >
> > > DMPlexCreateBoxMesh (.... );
> > >
> > > and get a uniform mesh. The mesh is periodic.
> > >
> > > We typically want to "scale" the coordinates (vertices) of
> the mesh,
> > > and
> > > to achieve this, we call
> > >
> > > DMGetCoordinatesLocal(dm, &coordinates);
> > >
> > > and scale the entries in the Vector coordinates appropriately.
> > >
> > > and then
> > >
> > > DMSetCoordinatesLocal(dm, coordinates);
> > >
> > >
> > > After this, we localise the coordinates by calling
> > >
> > > DMLocalizeCoordinates(dm);
> > >
> > > This worked fine up to PETSc 3.18, but with versions after
> this, the
> > > coordinates we get from the call
> > >
> > > DMPlexGetCellCoordinates(dm, CellID, &isDG, &CoordSize,
> > > &ArrayCoordinates, &Coordinates);
> > >
> > > are no longer correct if the mesh is periodic. A number of the
> > > coordinates returned from calling DMPlexGetCellCoordinates
> are wrong.
> > >
> > > I think, this is because DMLocalizeCoordinates is now
> automatically
> > > called within the routine DMPlexCreateBoxMesh.
> > >
> > > So, my question is: How should we scale the coordinates from
> a periodic
> > > DMPlex mesh so that they are reflected correctly when calling
> both
> > > DMGetCoordinatesLocal and DMPlexGetCellCoordinates, with
> PETSc versions
> > > >= 3.18?
> > >
> > >
> > > I think we might have to add an API function. For now, when you
> scale
> > > the coordinates,
> > > can you scale both copies?
> > >
> > > DMGetCoordinatesLocal()
> > > DMGetCellCoordinatesLocal();
> > >
> > > and then set them back.
> > >
> > > Thanks,
> > >
> > > Matt
> > >
> > > Many thanks, Berend.
> > >
> > > --
> > > 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/ <
> https://www.cse.buffalo.edu/~knepley/> <
> http://www.cse.buffalo.edu/~knepley/
> > <http://www.cse.buffalo.edu/~knepley/>>
> >
> >
> >
> > --
> > 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/>
>
--
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/>
