On Wed, 20 Jun 2018, Derek Gaston wrote:
Right now I have exactly _one_ var group (which makes this even more
puzzling)...
No kidding. How many variables in the group?
and I'm trying to just pull out the first dof from that group
using dof_indices(). I then do all the rest of my indexing off of
that first dof for all the other dofs in the group.
You mean using dof_number()? DofMap::dof_indices() will at minimum
return you all the dofs for a single variable.
Maybe there's a better way to be doing that? Is there a more
straightforward way to get the first dof in a var_group?
No, but (if you're using dof_number()) it sounds like what you want is
a dof_number_group() call instead. Then you can determine vg and vig
*once* rather than in each dof_number() call.
We could use the same thing in DofMap::_dof_indices and
DofMap::old_dof_indices if it works well.
I think I wouldn't mind just storing a var_num->var_group vector
somewhere that every DofObject has access to. The variable numbers
are always contiguous starting from 0 so we should just be able to
index into it.
The trouble is "has access to". I'd rather avoid adding another 8
bytes per node+elem if we can.
Wait, I'm being stupid. We don't actually have to make a pointer to
it a member variable! Every time we call dof_number() we're doing so
with a DofMap in hand, so it would be easy to cache lookups there and
then pass a DofMap * to the DofObject as an argument with which to
access that cache.
---
Roy
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