From: <ti...@ce...> - 2007-06-19 15:09:12
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Dear Roy, On Tue, 19 Jun 2007, Roy Stogner wrote: > On Tue, 19 Jun 2007, Tim Kr=F6ger wrote: > >> There is only one thing I would require further: For the Tet4 (and Tet10= )=20 >> elements, I would like the user to be able to influence the choice of th= e=20 >> diagonal along which the middle octrahedron of the tetrahedron is divide= d=20 >> into four tetrahedra. I.e., I would like a function >>=20 >> Tet4::influence_diagonal_selection(Tet4::Diagonal); >>=20 >> (and the same for Tet10). Would you accept such a function in your=20 >> library? > > The idea is certainly a good one, but how is the interface supposed to > work? My idea was that the user has to call the above function *before* the=20 element is actually refined. (It should be possible for the user to=20 compute the required choice in advance.) > We want to pick the shortest diagonal, I assume, where the definition > of "shortest" has changed since the refinement? Not always, in my particular application. > How about a function > like Tet::reselect_diagonal(); you'd call it on each parent Tet after > a refinement / node perturbation step, it would delete and recreate > children where appropriate, and then you'd call > EquationSystems::reinit() to do all the housekeeping and solution > projection work. Sounds even better than my idea, i.e. more user friendly; but also=20 more difficult to implement. I'll think about this, since I guess I=20 would be the person to implement that function. (If *you* want to=20 implement it, feel free ...) > One concern that just came to mind with the nodal perturbation idea: > will hanging degree of freedom constraints be calculated correctly? > The generic create_proj_constraints code should be able to cope, but I > think some of the coefficients for the specialized LAGRANGE code may > be hard coded, in which case you'd have to use HIERARCHIC elements > instead. The DoFs will be the same on a Tet4, of course, but they'll > use the more generic code paths. Thank you for that clue. Actually, for my particular application, I'm=20 not sure whether hanging nodes will at all occur on anisotropically=20 refined edges. Anyway, perhaps I should just use HIERARCHIC to be=20 sure. Best Regards, Tim |