Question #103034 on DOLFIN changed: https://answers.launchpad.net/dolfin/+question/103034
Murtazo Nazarov posted a new comment: 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 > > It seems the numbering is as the following: int nsdim = mesh.topology().dim(); int num_en = 1 + nsdim; // number of vertices's on the cell real L_inf_K = 0.; for (int i = 0; i < num_en ; i++){ L_inf_K = max(L_inf_K, fabs(my_arr[num_en*cid + i])); } probably there is a better way, but this works for now in one cpu (maybe not in parallel). murtazo >>>> 2. ||\div(Pu)||_{L_1} ? >>>> >>>> >>>> >>> Try >>> >>> M = abs(div(Pu))*dx >>> >>> -- >>> Anders >>> >>> >>> >>> >>> >>>> 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
