Hi, Dr. W. Bangerth, Thank you so much for your timely help!
I will try it and come back if I have further questions. Best regards, Zhidong Brian Zhang On Saturday, October 19, 2019 at 10:56:47 AM UTC-4, Wolfgang Bangerth wrote: > > > Zhidong, > > > In short, my question is how to get the cell_id properly by using CellId > class ? > > > > I want to assign each cell with a different value (its pesudo density in > > topology optimization). All the values are stored in a cell-based vector > x, > > which is initialized as follows, > > > > opt->x.reinit(opt->mpi_communicator, > > opt->triangulation.n_global_active_cells(), > > opt->triangulation.n_locally_owned_active_cells(), > > false); > > > > Now I want to access to x value in each cell. My basic idea is to get > the > > cell_id and then use x(cell_id). In order to get cell_id, I found I > should use > > CellId class, specifically, cell->id().to_string(). > > I think this is the wrong approach. The cell ids are used to globally > identify > cells, but there is no easy way to translate between cell ids and an index > into vectors. What you want to do is create another finite element field > that > is piecewise constant, i.e., using FE_DGQ(0). Such fields have exactly one > value per cell, and they can be accessed like any other field-based > quantity. > > Best > W. > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: [email protected] > <javascript:> > www: http://www.math.colostate.edu/~bangerth/ > > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/ad39331b-32bd-411f-ac30-c56b385e2cf9%40googlegroups.com.
