[petsc-dev] DMDA_*PERIODIC and DMDA_XYZGHOSTED

[Jed Brown]

On Tue, Dec 7, 2010 at 21:31, Dmitry Karpeyev <dkarpeev at gmail.com> wrote:

> I actually prefer the model where a geometric object (e.g., a DA) controls
> the restriction (e.g., DAGlobalToLocalBegin, etc).


Okay, but does the user need to use something like DMSliced just to update a
local form?

Things like VecView already need a way to follow an upward link to a DM.
 There is a delicate issue of circular dependencies if _p_Vec was given a
slot for the DA.  On the one hand, I feel like it would be cleaner if every
Vec had a link to _some_ DM, which, as far as the Vec is concerned, is just
a "function space".  The default implementation would be flat Cartesian
space.  On the other hand, it makes a dependency loop unless you always pass
pairs (DM,Vec) around (ugly and weird), or (a very limited subset of) the DM
API becomes part of the Vec "package".
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20101207/b25e2069/attachment.html>