On 9 June 2014 20:58, Martin Sandve Alnæs <[email protected]> wrote:
> I object to changing definitions based on that it would work out nicely > for one particular equation. The current definition yields a scalar jump > for both scalar and vector valued quantities, and the definition was chosen > for a reason. I'm pretty sure it's in use. Adding a tensor_jump on the > other hand wouldn't break any older programs. > > Maybe Kristian has an opinion here, cc to get his attention. > I follow the list, but thanks anyway. The current implementation of the jump() operator follows the definition often used in papers (e.g. UNIFIED ANALYSIS OF DISCONTINUOUS GALERKIN METHODS FOR ELLIPTIC PROBLEMS, arnold et al. http://epubs.siam.org/doi/abs/10.1137/S0036142901384162) where the jump of scalar valued function result in a vector, and the jump of a vector valued function result in a scalar. Adding the tensor_jump() function seems like a good solution in this case as I don't see a simple way of overloading the current jump() function to return the tensor jump. Kristian Martin > 9. juni 2014 20:16 skrev "Anders Logg" <[email protected]> følgende: > > On Mon, Jun 09, 2014 at 11:30:09AM +0200, Jan Blechta wrote: >> > On Mon, 9 Jun 2014 11:10:12 +0200 >> > Anders Logg <[email protected]> wrote: >> > >> > > For vector elements, the jump() operator in UFL is defined as follows: >> > > >> > > dot(v('+'), n('+')) + dot(v('-'), n('-')) >> > > >> > > I'd like to argue that it should instead be implemented like so: >> > > >> > > outer(v('+'), n('+')) + outer(v('-'), n('-')) >> > >> > This inconsistency has been already encountered by users >> > http://fenicsproject.org/qa/359/discontinuous-galerkin-jump-operators >> >> Interesting! I hadn't noticed. >> >> Are there any objections to changing this definition in UFL? >> >> -- >> Anders >> _______________________________________________ >> fenics mailing list >> [email protected] >> http://fenicsproject.org/mailman/listinfo/fenics >> >
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