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[Anders Logg <question103034@xxxxxxxxxxxxxxxxxxxxx>]

Question #103034 on DOLFIN changed:
https://answers.launchpad.net/dolfin/+question/103034

Anders Logg posted a new comment:
On Sun, Mar 14, 2010 at 11:48:21PM -0000, Murtazo Nazarov wrote:
> Question #103034 on DOLFIN changed:
> https://answers.launchpad.net/dolfin/+question/103034
>
> Murtazo Nazarov posted a new comment:
> Murtazo Nazarov wrote:
> > Your question #103034 on DOLFIN changed:
> > https://answers.launchpad.net/dolfin/+question/103034
> >
> >     Status: Answered => Open
> >
> > You are still having a problem:
> > Anders Logg wrote:
> >
> >> Question #103034 on DOLFIN changed:
> >> https://answers.launchpad.net/dolfin/+question/103034
> >>
> >>     Status: Open => Answered
> >>
> >> Anders Logg proposed the following answer:
> >> On Wed, Mar 03, 2010 at 02:36:59AM -0000, Murtazo Nazarov wrote:
> >>
> >>
> >>> New question #103034 on DOLFIN:
> >>> https://answers.launchpad.net/dolfin/+question/103034
> >>>
> >>> Hi,
> >>>
> >>> I am wondering how to compute an L1-norm, and L_inf norm of a functional on the cell. For instance how to compute
> >>>
> >>> 1. ||\div(Pu)||_{L_\infty} ?
> >>>
> >>>
> >> Try projecting div(Pu) onto piecewise constants and then pick the
> >> largest absolute value in the vector.
> >>
> >>
> >>
> >
> > I need L_inf norm on the cell. With this way, doesn't give the L_inf for
> > the entire domain?
> >
> > murtazo
> >
> >
>
> Instead of projecting div(Pu) onto piecewise constants, I projected it
> into dG(1), with this way I get three values on each cell, which I can
> then pick up the largest of them. That gives me then L_inf_K, where K is
> a cell. Now, I cannot figured out how is the numbering done for the
> dG(1) elements.
>
> If N is a total number of cells, then my projected vector Pdg has 3*N
> elements. How can I pick up elements of Pdg in the cell K?
>
> Thanks,
> murtazo

Why do you use DG(1) instead of DG(0)? If you use DG(0), the numbering
is easier.

--
Anders


> >>> 2. ||\div(Pu)||_{L_1} ?
> >>>
> >>>
> >> Try
> >>
> >> M = abs(div(Pu))*dx
> >>
> >>
> >>
> >>
> >>
> >>> where u is velocity (vector) and P is pressure (scalar). L2 norm is obvious to do.
> >>>
> >>> I use C++ interface
> >>>
> >>>
> >>>
> >>
> >
> >
>

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