I already implemented a GFEM in Matlab solving these equations, which
works just fine. So I'd assumed, it must be possible to solve these
equations also using deal.II.
I'm now switching to deal.II due to performance issues. The given eqns
are actually linearized eqns of the ones I later want to solve and here
Matlab performs very badly.
Markus Bürg wrote:
Hello Timo,
you are solving a first-order PDE. Usually these are not stable in
Galerkin formulation. Have you checked the stability?
Best Regards,
Markus
Am 30.03.11 11:15, schrieb Timo Koellner:
Hi folks,
I just started working with deal.II and do experience some problems
with solving the following equations:
\nabla n = 0
\nabla \vec{E} = -e(n - \Theta(x))
For simplicity, I started off in 1d where I can solve the equations
analytically. The problem I'm stuck with is
"Exception on processing:
Iterative method reported convergence failure in step 1 with residual
nan"
I attached the program so you can have a look. What I actually did is
to take the Step-by-Step example on periodic boundary conditions
(since in higher dimensions I want to apply them) and modified it
using a FESystem and of course inserted my equations and left out the
periodics as I don't need them in 1d.
I tried using different Solver classes ending up with the same error.
So, I guess there's something wrong with setting up the system, but
after rereading the examples and the explanations on the module for
solving vector-valued eqns, I have no idea what's going wrong.
Am I missing something?
I would appreciate any help on this. Thanks.
Timo
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