[Carpet] Restriction and interpolation

[Ian Hinder]

Erik Schnetter wrote:
> On Sep 1, 2006, at 15:37:44, Ian Hinder wrote:
> 
>> Hi,
>>
>> Is it true that quantities computed in the ANALYSIS bin are not
>> restricted?  This seems to be the case both from looking at
>> doc/internals and doc/scheduling, and also the output from my code.
>> What is the rationale for this?
> 
> This is true.  The rationale is that the analysis bin is executed after
> restriction.  The time at which restriction occurs has a definite place
> in the Berger-Oliger time evolution algorithm -- unlike boundary
> prolongation, which can happen at any time.  (This is partly only a
> design decision in Carpet.)
> 
> If you want to calculate norms or interpolate or look at reasonable I/O
> of quantities, it is almost always necessary to calculate them in the
> evol bin, and to allocate three time levels for them.  Only then can you
> prolongate the mesh refinement boundaries, which requires interpolation
> in time.  If you want to restrict quantities, then there is no advantage
> in scheduling them in the analysis bin, since you very likely need to
> calculate them at all time steps anyway.

Is it necessary to calculate them in EVOL directly, or is POSTSTEP
sufficient?  What scheduling semantics should I use? 'in EVOL after
MoL_Evolution'?

-- 
Ian Hinder
hinder at gravity.psu.edu
http://www.gravity.psu.edu/~hinder