On Tue, Feb 28, 2012 at 13:52, Dmitry Karpeev <karpeev at mcs.anl.gov> wrote:
> I don't understand the need for multiple function evaluation routines and > their explicit naming. > I think the situation here is completely analogous to the situation with > matrices: I thought we agreed that each DM would be capable of generating a > single matrix, the "Jacobian", rather than multiple matrices like J and > J_pre, and that the different necessary matrices (again, e.g., J and J_pre) > would instead be produced by their respective DMs -- the KSP DM and the PC > DM, so to speak. These subDMs would be pulled out of the SNES DM and > passed to the corresponding KSP and PC objects. Thus, a DM encapsulates a > single "problem", and if we want to get a different problem -- the "exact" > linearization of the original, for example -- we extract the KSP DM; > likewise, PC DM is an approximate linearization, and so on. > > I don't think TS is any different -- we can have the TSI DM (maybe under a > better name), which could have DMFormFunction encapsulating the IFunction > (and, incidentally, a linearization encapsulating the mass matrix), etc. > I'm concerned that this becomes insanity. A single TS might need RHSFunction, IFunction, and IJacobian. They might also partition terms differently for the functions and the Jacobian. Having different DMs seems awfully confusing. In short -- I'm for each DM having one function (DMFormFunction or, better, > DMFormResidual) and one matrix (DMFormJacobian) -- *a* linearization of the > residual. All other functions and matrices are obtained from the > corresponding subDMs. > The interface is actually different for these (compare TSIFunction, a transient residual, to SNESFunction) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20120228/f8d060d1/attachment.html>
