[ET Trac] [Einstein Toolkit] #350: Autogenerating cctk_Loop.h

[Einstein Toolkit]

#350: Autogenerating cctk_Loop.h
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  Reporter:  eschnett     |       Owner:        
      Type:  enhancement  |      Status:  review
  Priority:  minor        |   Milestone:        
 Component:  Cactus       |     Version:        
Resolution:               |    Keywords:        
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Comment (by eschnett):

 2. Ok.

 3. If we use CCTK_NORMAL for the normal, then we should also use
 CCTK_INDEX for the loop index... Joke aside, we can store the distance
 from the outer boundary in the normal. (The "number of points less than
 the boundary size which are available" would be less useful -- it would be
 large at the boundary, and small in the interior, thus it wouldn't
 indicate what stencil you can use.)

 4. The issue isn't looping over physics vs. looping over symmetry zones.
 The issue is that there are three boundary specifiers (physical, symmetry,
 ghost), and in three dimension, and boundary can have up to three
 specifies attach to it (corners!). Yes, a boundary can be all of a
 physical, a symmetry, and a ghost boundary. The issue is in handling
 these. BOUNDARIES loops over all boundaries that are physical boundaries
 (irrespective of whether they are also a symmetry or a ghost boundary),
 INTBOUNDARIES loops over all boundaries that are only physical boundaries.
 The former does not require applying symmetry conditions and
 synchronisation afterwards, the latter allows taking tangential
 derivatives.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/350#comment:13>
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