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 >> >>
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