On 14 August 2014 11:09, Martin Sandve Alnæs <[email protected]> wrote:
> On 14 August 2014 10:38, Garth N. Wells <[email protected]> wrote: > >> I favour (a) explicit provision of the element/function space; or (b) >> evaluation at quadrature points with errors for cases where no data is >> available for deciding on a sensible quadrature scheme. Using quadrature >> points would fix some other awkward issues, like specifying boundary >> conditions on polygon faces which 'creep' around corners is subdomains are >> not marked. >> > > > I agree with both (a) and (b). > I see I was a bit quick there. I favour evaluation at quadrature points for cases where no element/function space is provided, combined with making the choice of quadrature degree/scheme easier accessible with dx(degree=3) notation. Maybe we can add in a "Warning: automatic selection of integration degree 3, this may be inexact.". The quadrature degree estimation is just that: an _estimation_. It is not exact for any non-polynomial expressions. If we want to throw an error when the degree for exact integration cannot be determined, that is a partially separate issue from this one, and it will break a lot of programs. If we want integration involving any Expression without an element to be guaranteed exact, we will need to require the integration degree to be set explicitly. This will probably break every single dolfin demo. Martin
_______________________________________________ fenics mailing list [email protected] http://fenicsproject.org/mailman/listinfo/fenics
