On 5/1/10 1:23 PM, Roy Stogner wrote:
>
> On Sat, 1 May 2010, Boyce Griffith wrote:
>
>> and to prevent children of inactive elements which
>> satisfy this threshold from being coarsened. All other elements would
>> be flagged for coarsening.
>
> You mean that children of inactive elements which *don't* satisfy this
> threshold wouldn't be coarsened, right? In that case you'd just have
> to set the parent element ErrorVector components too.

What I mean here is --- inactive elements which satisfy the criterion 
should have their children flagged to be neither refined nor coarsened.

>> Is there a straightforward way to do using MeshRefinement?
>
> Not quite straightforward. flag_elements_by_error_tolerance would
> almost do what you want if you set refine_fraction = coarsen_fraction
> = 1, but it tries to satisfy a global tolerance (typically on a
> squared norm of error IIRC) and it calculates a per-element tolerance
> by splitting that up by n_elem.
>
>> Or am I better off flagging elements "by hand"?
>
> Flagging by hand would be as easy as writing your own estimator. The
> only advantage of the MeshRefinement method is flexibility - it'd be
> easy to add hysteresis, experiment with less-than 100%
> refinement/coarsening fractions, or switch estimators later.

If I do this manually, do I set flags only for active elements, or do I 
need to flag all elements?

Thanks,

-- Boyce

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