On Oct 16, 2012, at 12:00 AM, Matthew Knepley <knepley at gmail.com> wrote:
> On Tue, Oct 16, 2012 at 3:52 PM, Barry Smith <bsmith at mcs.anl.gov> wrote: > > On Oct 15, 2012, at 11:48 PM, Matthew Knepley <knepley at gmail.com> wrote: > > > On Tue, Oct 16, 2012 at 3:24 PM, Barry Smith <bsmith at mcs.anl.gov> wrote: > > > > It is seriously misleading that TSType rosw uses SNES as the solver > > since it is only using SNESKSP and the algorithm really is built around > > only linear solves. Are you sure that using SNES is the right model for > > this family of algorithms? Convince me. > > > > I realize one person among us thinks we should use SNES for both linear > > and nonlinear solves, but he is wrong :-) > > > > Let me try a Venn Diagram: > > _________________________________ > > / _____________ \ > > | / \ | > > | Nonlinear problems | Linear problems | | > > | \ _____________/ | > > \_________________________________/ > > > > Also, there is no overhead using SNES, so I would say Do Not Multiply > > Entities Beyond The Necessary. > > I am not concerned about overhead. I am concerned about things looking > like they are doing one thing but that are actually doing something else. In > this case, there is actually a nonlinear problem hanging around but the rosw > algorithms avoid solving it, which is ok but I find the fact that it prints > SNES is then misleading because given a nonlinear problem and SNES one would > think it is actually solving a nonlinear problem with SNES, when it is not. > > It is solving a nonlinear problem, just a really easy one :) Yes but it is not solving THE nonlinear problem in question. It is a solving a nonlinear problem (that happens to be linear) defined by the Jacobian. Note: I am objecting to how rosw uses SNESKSP, I am not objecting to SNESKSP. Barry > I guess you could setup the SNES to > turn on the KSP monitor instead. > > Matt > > > > > Matt > > > > Matt > > > > > > Barry > > > > > > > > > > -- > > What most experimenters take for granted before they begin their > > experiments is infinitely more interesting than any results to which their > > experiments lead. > > -- Norbert Wiener > > > > > -- > What most experimenters take for granted before they begin their experiments > is infinitely more interesting than any results to which their experiments > lead. > -- Norbert Wiener
