Hi Toby,

> I am wondering if the DoFRenumbering algorithms operate on
> the dof_handler associated with distributed grids (triangulation).
> in dofs/dof_renumbering.cc there is little mention of distributed dofs.
>
>  dof_handler.distribute_dofs (fe);
>  dealii::DoFRenumbering::Cuthill_McKee (dof_handler); // added this

If I remember correctly, only component_wise and custom (handwritten)
reordering is supported for distributed meshes. Cuthill_mckee is a bad
idea anyhow in parallel. It would create a SparsityPattern
representing the coupling between the DoFs for all DoFs on every
machine and then try to optimize the ordering. Even if we had the
information (we no longer have), this does not work in practice due to
memory and complexity. One could think about doing something only on
the locally_owned DoFs, though.

Best,
Timo

-- 
Timo Heister
http://num.math.uni-goettingen.de/~heister
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