And yet DMDA already defines this local fine-granularity "stencil" access. Where would it go, if not in the DM? In my opinion this is part of the function space definition: it generalizes VecGetArray to something more geometric. Not all DMs have to implement this.
On Tue, Dec 7, 2010 at 3:35 PM, Jed Brown <jed at 59a2.org> wrote: > On Tue, Dec 7, 2010 at 22:06, Dmitry Karpeev <karpeev at mcs.anl.gov> wrote: > >> But those that *want* to know, can obtain the underlying DM and start >> doing cool stuff >> to the Vec. In particular, DM is the natural place to inject geometric >> information, generalizing DMDA to the unstructured >> case. For example, a DM can allow to access the Vec data by "stencil", >> which in the DMDA case is the usual thing, >> and in the unstructured mesh case is, say, element restrictions. This >> would encapsulate the "expanded space" idea >> that Jed described a while ago in a tentative unstructured API. This >> would require, however, some iterator model, >> which is a kind of flexible local fine-granularity "on demand" scatter. >> > > This functionality is all in Level 3 of my earlier message, it's not a part > of the DM API that Vec should be aware of. > > The only parts of the DM API that I think Vec should be aware of is > PetscLayout, the "overlap" scatters, and DMVecView. The last one is purely > cosmetic because VecGetDM, DMVecView is so common. > > Jed > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20101207/16ef8b4c/attachment.html>
