On Tue, Nov 20, 2012 at 10:21 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> > On Nov 20, 2012, at 9:10 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote: > > > On Tue, Nov 20, 2012 at 3:08 PM, Barry Smith <bsmith at mcs.anl.gov> wrote: > > > > The object is called TSDM but methods are DMTSXXX()? > > > > DMTS... is right because they are methods on a DM, though they are > packaged with TS. The user _never_ sees the internal "TSDM" object. I think > the original motivation for that naming structure was to prevent conflict > with a TS/SNES implementation of the same name, but I would not object to > switching to DMTS > > > > > > TSDM is itself not a PETSc object but it is wrapped into a > PetscContainer (which is a PETSc object), so why not just make TSDM a PETSc > object? Is it because of circular references? > > > > I don't mind making it a PetscObject. > > > > What's with the complicated DMTSGetContextWrite() (copy on write > crapola) stuff? This kind of paradigm is not used anywhere else in PETSc, > is it really needed? Seems overly complex, is it just to save a few small > objects? > > > > It's for interface simplicity. If the user sets the the residual routine > on the finest level and then changes it, they probably expect their change > to propagate through the levels. But if they get out a coarse level and > explicitly change it there, they probably intended to use a different > discretization/physics on the coarse level. > > How do they "get out a coarse level and explicitly change it" for > > 1) KSP? > 2) SNES? > 3) TS? > > > > > > > The DMTSGetContext() business uses PetscObjectCompose to attach the TSDM > to a dm. Why not just have DM's have opaque pointers to KSPDM, SNESDM, and > TSDM built into the DM and things > > like DMGetKSPDM() that do the usual dm->kspdm access instead of > composing business. Since the business of DM's is to talk to TS, SNES, and > KSP there is no reason to go through the more complicated object compose > business is there? (The object compose business is for out-of-the-ordinary > stashing of stuff, not ordinary stashing of stuff, it is kind of like using > object compose to attach the ksp to the snes). > > > > Okay, but when the optimizers need to attach something, do we add > special support for that in DM as well? > > Sure > > > What about UQ and so on? The idea here was to keep DM as ignorant as > possible, but allow it to carry this extra data around for the various > solver objects that need it. > > Ok, objectcompose is certainly more extensible. > > BTW: DMTSGetContext() is kind of a funky name, context is a very general > term, this function returns a TSDM (or DMTS) so could be DMGetDMTS() or > DMTSGetDMTS() > > Should it be DMGetTSDM? I'v'e thought this (DMTS vs TSDM) an awkward distinction for a while too. However, would removing weasel words like "Context" from the names make it more clear? - Peter > Barry > > > > > > Perhaps some refactoring could bring this stuff down to the > simple-minded design of the rest of PETSc? > > > > Barry > > > > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20121120/044f7704/attachment.html>
