Thank you so much! I did all of this and it works now. I had tried the dof
index before, but I think the output to a vtu file was wrong, so now I have
fixed that too.
Much appreciated,
Giselle
On Monday, December 18, 2023 at 4:55:25 p.m. UTC-5 Wolfgang Bangerth wrote:
>
> On 12/18/23 13:23, Giselle Sosa Jones wrote:
> > // Initialize vector
> > dof_handler_dg0.distribute_dofs(fe_dg0);
> > const std::vector<IndexSet> locally_owned_dofs_per_proc_dg0 =
> > DoFTools::locally_owned_dofs_per_subdomain(dof_handler_dg0);
> > locally_owned_dofs_dg0 =
> locally_owned_dofs_per_proc_dg0[this_mpi_process];
> > vec.reinit(locally_owned_dofs_dg0, mpi_communicator);
> >
> > // Calculate values
> > for (const auto &cell : dof_handler_dg0.active_cell_iterators())
> > {
> > double val;
> > if(cell->subdomain_id() == this_mpi_process)
> > {
> > val = compute_value<dim>(cell);
> > vec[cell->active_cell_index()] = val;
> > }
> > vec.compress(VectorOperation::insert);
> > }
>
> Gisella:
> There are potentially three problems with this code, though I don't know
> how many of these are actual ones :-)
>
> 1/ You treat the 'vec' vector as one associated with degrees of freedom,
> but you index into it with an active_cell_index. This isn't right. You
> need to index into it with the DoF index on this cell. I'm pretty sure
> this is already going to fix your issue.
>
> 2/ You want to do the vec.compress() call only once after assembly, not
> once per cell. In fact, I'm surprised this works the way you have it:
> compress() is a *collective* cell in which all processes must
> participate (or you will get a deadlock), but different processes will
> have different numbers of active cells, so they will call this function
> a different number of times.
>
> 3/ DataOut::add_data_vector() has a discussion that explains the 'type'
> argument, see
>
> https://dealii.org/developer/doxygen/deal.II/classDataOut__DoFData.html#ac43d3b1f6e67424f36e474627fe8e401
> You may want to read through that and perhaps provide an explicit value
> for the third argument (if you aren't already).
>
> Best
> W.
>
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