[petsc-dev] PetscSection

Jed Brown jedbrown at mcs.anl.gov
Sat Nov 10 14:19:29 CST 2012

On Sat, Nov 10, 2012 at 2:05 PM, Matthew Knepley <knepley at gmail.com> wrote:

> Well, you have to designate the set with something. The easiest thing to
> use is
> an integer, so I use that. This is the only value associated with the set,
> so I
> would say Labels really only make sets.

I was looking at DMComplexGetLabelValue() and didn't realize it's just one
value per stratum. So you get the value associated with a point by
searching to find which stratum it resides in. In the implementation, if
point is not in the set specified by the label, it does not set *value. Is
that intentional? And there is no way to query stratum values without
getting a point that is a member. What about if a given level happens to be

Also, linear search, oh my. ;-)

> Exactly, they are sorted by strata, not dimension.

Okay, then dimensional query would really need to return an IS, provided it
didn't switch to sorting by dimension.

Can you answer how you can distinguish a quad from a tet in a
non-interpolated mesh?
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