[Carpet] Restriction and interpolation

[Erik Schnetter]

On Sep 4, 2006, at 03:00:11, Ian Hinder wrote:

> 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'?

The poststep bin is also executed after restriction, same as the  
analysis bin.

If you have an analysis quantity that is defined locally, such as  
e.g. the constraints then yes, you have to schedule it

	IN evolution AFTER MoL_Evolution

If the quantity should also be available during all sub-timesteps,  
i.e. while the RHS is calculated, then you have to schedule it

	AT MoL_PostStep

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>

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