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[Kent-Andre Mardal <question143195@xxxxxxxxxxxxxxxxxxxxx>]

Question #143195 on DOLFIN changed:
https://answers.launchpad.net/dolfin/+question/143195

Kent-Andre Mardal proposed the following answer:
On 1 February 2011 18:48, David Ham
<question143195@xxxxxxxxxxxxxxxxxxxxx>wrote:

> Question #143195 on DOLFIN changed:
> https://answers.launchpad.net/dolfin/+question/143195
>
>     Status: Answered => Open
>
> David Ham is still having a problem:
> Thanks Kent, this is a useful insight into part of the problem.
>
> In the example you gave, the variable which is eliminated is in a
> continuous space and, if I understand the code correctly, you use mass
> lumping to invert the mass matrix in the Schur compliment.
>
> However this doesn't indicate how one would do this in the DG case for
> which the mass can be directly inverted. So I guess the direct question
> is, is there a way in Dolfin assembling the inverse of the local tensor?
> Ie something like:
>
> assemble(inverse(u*v*dx))
>
> Many thanks,
>
> David
>
>
Nope, you could however create the matrix yourself in various ways, eg. by
running over the mesh
with an assemble like function. Or, the best option is of course to add it
to UFL. Depends on your perspective.

Kent



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