On Wed, Feb 16, 2011 at 05:07:57PM +0000, Garth N. Wells wrote: > > > On 16/02/11 16:54, Johan Hake wrote: > > Question #145534 on DOLFIN changed: > > https://answers.launchpad.net/dolfin/+question/145534 > > > > Johan Hake proposed the following answer: > > On Wednesday February 16 2011 08:48:38 Anders Logg wrote: > >> Question #145534 on DOLFIN changed: > >> https://answers.launchpad.net/dolfin/+question/145534 > >> > >> Status: Open => Answered > >> > >> Anders Logg proposed the following answer: > >> > >> On Tue, Feb 15, 2011 at 10:30:06PM -0000, Yi Jiang wrote: > >>> New question #145534 on DOLFIN: > >>> https://answers.launchpad.net/dolfin/+question/145534 > >>> > >>> Hi all, > >>> > >>> I am using the dolfin to solve a PDE problem by finite element method. > >>> However, I met a problem when I try to define the linear form L(v) of > >>> right hand side. Suppose the PDE is: > >>> > >>> F(x) = f. > >>> > >>> What should I do if the f is a Dirac Delta function. How to define it in > >>> ufl? Anybody met and solved the similar problems before? > >>> Thank you for attention and kind help. > >> > >> This is not supported. > > > > I am also interested in this. What would it require to implement? Changes to > > UFL, FFC, DOLFIN? > > > > A lot of changes. It would require being able to integrate over > surfaces/lines within a cell.
It would be good to be able to approximate by a suitably scaled value at a single vertex, either the closest vertex to a given point specified by a vertex index. -- Anders > UFL can be stretched to do this, but extentions to FFC and DOLFIN are > needed. Take a look at the modelling discontinuities chapter in the > FEniCS book ;). _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : [email protected] Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
