[dune-pdelab] Inquiry

[Jared Okiro]

Thanks Joe for the response. I want to implement Alexander3Parameter time
stepping scheme.
Do I need to do jacobian_ volume( ) of the temporal operator then?.
Regards,
Jared

On Tue, Sep 20, 2011 at 12:35 PM, Jö Fahlke <jorrit at jorrit.de> wrote:

> Am Tue, 20. Sep 2011, 08:44:57 +0200 schrieb Jared Okiro:
> > I am a new dune user, and is developing a DG code for a
> reaction-diffusion
> > system.
> > When I look at the example code in
> > dune/pdelab/localoperator/convectiondiffusiondg.hh,
> > I see two ways of doing the residual assembly i.e alpha volume and
> jacobian
> > volume.
> > Can someone help me understand the difference between these two functions
> in
> > setting up
> > the system?. I am asking this because in standard Galerkin methods, I
> only
> > see alpha volume
> > but not jacobian volume also.
>
> Well, jacobian_volume() is needed when you need to assemble and solve a
> matrix, i.e. for stationary or implicit instationary problems.  If you
> don't
> want to implement both of alpha_volume() and jacobian_volume() you can
> derive
> your local operator from NumericalJacobianVolume.  This implements
> jacobian_volume() using alpha_volume() an numerical differenciation.
> Alternatively, if you have a *linear* problem and don't want to implement
> alpha_volume(), you can derive your local operator from
> JacobianBasedAlphaVolume.
>
> > Finally, my problem is of the form:
> >
> > *\frac{\partial u}{\partial t} = D \ Delta u + f(u) = 0  in \Omega,*
> where
> > f(u) is a non-linear function.
> >
> > Do I need to do jacobian volume of the temporal operator also or the
> alpha
> > volume is sufficient?
>
> That depends on your time-stepping scheme.
>
> Bye,
> Jö.
>
> --
> In the beginning the Universe was created.  This has made a lot of
> people very angry and been widely regarded as a bad move.
> -- Douglas Adams
>
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.10 (GNU/Linux)
>
> iQIVAwUBTnhsXumx9CKgc0OWAQgCpg//YHdlNTg511KPQ+fvHFQXAlJOj2oq2PBY
> UOMK+6i4erESoEfvoV1Fi0Qp/0heFE5Lp7KGMc7fAXns7i8kSmtmIgY5o2meSb4c
> 8aZLMOZWHouALzNxLlgN1MVLWC9CFToMxEIK3TNGfIO4CC1vyd02CTDvx2B9mL+Z
> 2aSlEjW7KTZ/iah6XVei+bLQecSKF09ea97y1ywOD2ruKd1pdJXimihW+ikLoesp
> L1mq+1jKrx5Gn+Y+XMwjwWVTifLqVerYAUFOhp/kleQeCcR4zVnZjC2kcsmWD8Xq
> eAKVQhOsmAB6IbqUndj0Yo7S/WxMXG9A12nXCkrKsEgUU/grRbesFhM41VL1ZPNb
> SeKUoKFcKbqrjACRr9JozyU5kdW0S1C9EIl3CQx2lBr0Mt6IbwCG/QzeOJXP4C5a
> gfjoBYcfN31uq2jjJaWESGTcZVzyMD2+XXRz7DPt0fgH8eHwPJovzZEfwTv+7EbW
> X2t/3gl18LD7mq5OijmJTtjRnVgEzXXssaZ8fq/fa7u1WXT8RJC3FDuzXXDeC7cp
> dmpQssmp55aP8A5DbxHUqvSdwx/QOxps9Cy7HJADRyFe7KyEvdadnby7xk7Wlvp7
> PtoLAMmT+0ulG89gBW3xHZTVuyypc/4fOt6RpupLMqeL2p/UGLUUdsnKHnxgV0Pr
> vRckb1wTOlM=
> =bm7o
> -----END PGP SIGNATURE-----
>
>


-- 
Jared Ouma Okiro,
Institute for Analysis and Numerics,
Otto-von- Guericke Universität,
Universitätsplatz 02, Gebaude 02 / 115
39106 Magdeburg, Germany
Office Tel: +493916712660
Fax:         +493916718073
Mobile:     +4917657479787
Home Tel: +4939155917376
Email:jared.okiro at st.ovgu.de
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.dune-project.org/pipermail/dune-pdelab/attachments/20110920/a194e301/attachment.htm>