Hi, I believe something similar has been up for discussion before when I implemented some algorithms for local averaging and Kent-André at the time referred to this as a macro element used for Clement interpolation. Any fresh thoughts on this Kent?
Mikael > On 20 Apr 2015, at 18:11, Jan Blechta <[email protected]> wrote: > > I'm probably the stupid one here, but it seems to me that DOF > functionals couldn't be local in this case. (As it showed up currently > with enriched spaces, it is not necessary to have them implemented but > is very desirable.) Any ideas? > > Jan > > > On Mon, 20 Apr 2015 16:00:52 +0000 > Anders Logg <[email protected]> wrote: > >> Yes, it might actually be that simple: The elements would be standard >> P1 elements with the only difference that the value of the basis >> functions are always one (each triangle has 3 basis function and each >> is = 1) and all derivatives are zero. >> >> Might be possible to "hack" by modifying >> _create_fiat_element(ufl_element) in ffc/fiatinterface.py. >> >> -- >> Anders >> >> >> mån 20 apr. 2015 kl 17:44 skrev Martin Sandve Alnæs >> <[email protected]>: >> >>> Doesn't sound that hard. Basically dofmaps like CG1 elements with >>> basis functions replaced by 1.0 on the entire support? >>> On 20 April 2015 at 15:37, Joakim Bø <[email protected]> wrote: >>> >>>> Thanks for answering! >>>> >>>> >>>> Anders got it right, discontinous and overlapping basis functions >>>> with the same global support as P1 tent functions. Sorry to hear >>>> that it would be hard to implement, but it came as no surprise... >>>> >>>> >>>> Thanks anyway! >>>> >>>> >>>> Joakim >>>> >>>> >>>> -- >>>> Joakim Bø >>>> Prosjektleder ENT3R UiO >>>> Tlf.: 915 24 326 >>>> >>>> http://www.ENT3R.no/OSLO >>>> ------------------------------ >>>> *From:* Anders Logg <[email protected]> >>>> *Sent:* 20 April 2015 13:46 >>>> *To:* Andrew McRae; Jan Blechta >>>> *Cc:* Joakim Bø; [email protected] >>>> *Subject:* Re: [FEniCS] Implement a new finite element type for >>>> testing purposes? >>>> >>>> If I understand correctly, you want discontinuous and overlapping >>>> basis functions with the same global support as the P1 tent >>>> functions. Unless you find a clever trick for how to treat this >>>> (perhaps via some linear algebra using P0 elements in combination >>>> with some suitable constraints), this looks difficult to implement >>>> in FEniCS. We assume each element is defined locally on >>>> triangles/tetrahedra. >>>> >>>> -- >>>> Anders >>>> >>>> >>>> mån 20 apr. 2015 kl 13:14 skrev Andrew McRae >>>> <[email protected]>: >>>> >>>>> I interpret it as a DG0, but where nodes are associated with >>>>> vertices. Related to mass-lumping, I guess. >>>>> >>>>> On 20 April 2015 at 12:07, Jan Blechta >>>>> <[email protected]> wrote: >>>>> >>>>>> On Fri, 17 Apr 2015 10:21:33 +0000 >>>>>> Joakim Bø <[email protected]> wrote: >>>>>> >>>>>>> Hi! >>>>>>> >>>>>>> >>>>>>> I am in need of a new type of basis function for testing >>>>>>> purposes. It is much similar to the basis functions of the >>>>>>> Taylor-Hood P1 element, the difference is that the functions >>>>>>> are piecewise constant equal to 1 in this "local >>>>>>> domain" (similar for 1D and 3D): >>>>>>> >>>>>>> >>>>>>> [http://www.fsz.bme.hu/~szirmay/radiosit/rad10.gif] >>>>>>> >>>>>>> >>>>>>> and zero in the rest of the domain. In general, phi_i = 1 for >>>>>>> "local domain of dof i", 0 else. >>>>>> >>>>>> If I understand your explanation correctly (it does not seem to >>>>>> match with the figure!), it is Discontinuous Lagrange element of >>>>>> degree 0, which is implemented. >>>>>> >>>>>> Jan >>>>>> >>>>>>> >>>>>>> >>>>>>> Would it be possible to implement this without too much work? >>>>>>> Or would it require a lot of effort? >>>>>>> >>>>>>> >>>>>>> Thanks! >>>>>>> >>>>>>> Joakim >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Joakim Bø >>>>>>> Prosjektleder ENT3R UiO >>>>>>> Tlf.: 915 24 326 >>>>>>> >>>>>>> http://www.ENT3R.no/OSLO >>>>>> >>>>>> _______________________________________________ >>>>>> fenics mailing list >>>>>> [email protected] >>>>>> http://fenicsproject.org/mailman/listinfo/fenics >>>>>> >>>>> >>>>> >>>> _______________________________________________ >>>> fenics mailing list >>>> [email protected] >>>> http://fenicsproject.org/mailman/listinfo/fenics >>>> >>>> > > _______________________________________________ > fenics mailing list > [email protected] > http://fenicsproject.org/mailman/listinfo/fenics _______________________________________________ fenics mailing list [email protected] http://fenicsproject.org/mailman/listinfo/fenics
