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 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 > > I have some problem with dofmap for dG(1) elements. Here the piece of the code I am using: const DofMap& dofmap = U.function_space().dofmap(); real Umax = 0.; UFCCell ufc_cell(*cell); uint dofsize = dofmap.max_local_dimension(); uint* cell_dofs = new uint[dofsize]; dofmap.tabulate_dofs(cell_dofs, ufc_cell, cid); for (int i = 0; i < dofsize; i++){ Umax = max(Umax, fabs(Uarr[cell_dofs[i]])); } It works fine for dG(0), however it gives strange results for dG(1). Can anyone help? Thanks, Murtazo > >>> >>> >>>>>>> 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
