On Thu, 23 Jan 2014 09:54:34 -0800 Nikolaus Rath <[email protected]> wrote:
> On 01/23/2014 09:25 AM, Jan Blechta wrote: > > On Thu, 23 Jan 2014 18:19:45 +0100 > > Jan Blechta <[email protected]> wrote: > > > >> On Thu, 23 Jan 2014 08:53:13 -0800 > >> Nikolaus Rath <[email protected]> wrote: > >> > >>> On 01/23/2014 04:19 AM, Jan Blechta wrote: > >>>> On Wed, 22 Jan 2014 11:39:30 -0800 > >>>> Nikolaus Rath <[email protected]> wrote: > >>>> > >>>>> Hi Jan, > >>>>> > >>>>> It was my impression from the other thread that I could handle > >>>>> the problem of multiple solutions by giving the nullspace to the > >>>>> solver. But I'll try the Laplace constraint as well. > >>>>> > >>>>> But then, even with u constrained, I still need to somehow put > >>>>> the same constraint on the test functions, don't I? That's the > >>>>> part I'm struggling with. > >>>> > >>>> Sure. This is why it seems logical to me to constraint both trial > >>>> and test space by Laplace equation. Nevertheless I did not think > >>>> it over a much. > >>> > >>> > >>> For what it's worth, it seems logical to me as well... I just > >>> don't know how to impose the second constraint. > >> > >> Check > >> http://fenicsproject.org/documentation/dolfin/1.3.0/python/demo/documented/neumann-poisson/python/documentation.html > >> > >> Testing by (v, 0) and (v + c, 0) gives linearly dependent > >> equations - in fact, the same. Similar construction can apply to > >> your problem. > > > > Here, I meant (v, 0) and (v + arbitrary_constant, 0). And it holds > > because "the sufficient condition" > > \int f \dx + \int g \ds = c |\Omega| > > is fulfilled. > > > I'm afraid I'm completely lost. What do you mean with "Testing by (v, > 0) and (v + arbitrary_constant, 0)", and what is |\Omega|? The > sufficient condition on the above link doesn't have this term... "Testing by foo" means set test function in the equation to foo and observe... |\Omega| is a measure of \Omega. You get "the sufficient condition" \int f \dx + \int g \ds = c |\Omega| when testing by (v, d) := (1, 0). It is in quotes, as it is no longer a sufficient condition but rather a property of the solution. Actually, the value of the multiplier c. Jan > > > > Thanks, > Nikolaus > > _______________________________________________ > fenics mailing list > [email protected] > http://fenicsproject.org/mailman/listinfo/fenics _______________________________________________ fenics mailing list [email protected] http://fenicsproject.org/mailman/listinfo/fenics
