Matthew Knepley <[email protected]> writes: > Someone had to do it. > > I will not try to frame the entire discussion. Barry has already thrown > down the "show me your interface" gauntlet. However, I want to emphasize > one point that may have been lost in the prior discussion. Every example I > have looked at so far is focused on the reduced space formulation of the > optimization problem. However, I am interested in the full space > formulation so that I can do multigrid on the entire optimal control > problem. This is not a new idea, in particular Borzi does this in SIAM > Review in 2009. I think we have a tremendous opportunity here since other > codes cannot do this, it has the potential (I think) for much better > globalization, and perhaps can be faster. > > So, when we come up with interface proposals, I think we should keep a full > space solution method in mind.
I don't see how any of the present interfaces work for waveform relaxation. I also think that is rarely a desirable technique -- too many awkward limitations. My recollection is that Borzi only uses it for parabolic problems, for which adaptivity would have given much faster/cheaper solutions of equivalent accuracy. The techniques are theoretically interesting, but have not demonstrated sufficient practicality to worry about. Someone doing research on these full-space methods can just discretize space-time using SNES.
