Question #103034 on DOLFIN changed: https://answers.launchpad.net/dolfin/+question/103034
Anders Logg posted a new comment: On Mon, Mar 15, 2010 at 03:45:30PM -0000, Murtazo Nazarov wrote: > Question #103034 on DOLFIN changed: > https://answers.launchpad.net/dolfin/+question/103034 > > Murtazo Nazarov posted a new comment: > Anders Logg wrote: > > Your 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. > > > > > > DG(0) gives me an average of the function I have on the cell, however > the values can be large on the vertices especially in the places where > shocks exist. > > murtazo ok, then I suggest working through tabulate_dofs in the DofMap class to get the degrees of freedom for any given cell. Then you can just access those from the vector. -- 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 > >>>>> > >>>>> > >>>>> > >>>>> > >>> > > > > > -- You received this question notification because you are a member of DOLFIN Team, which is an answer contact for DOLFIN. _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : [email protected] Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
