[ET Trac] [Einstein Toolkit] #1261: Suspicious logic in NewRad thorn

[Einstein Toolkit]

#1261: Suspicious logic in NewRad thorn
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  Reporter:  wolfgang.kastaun@…           |       Owner:            
      Type:  defect                       |      Status:  review    
  Priority:  major                        |   Milestone:  ET_2012_11
 Component:  EinsteinToolkit thorn        |     Version:  ET_2012_11
Resolution:                               |    Keywords:  backport  
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Comment (by eschnett):

 The condition (is_physbnd or not is_ipbnd) does not make sense; since
 physbnd and ipbnd are exclusive, this is equivalent to (not is_ipbnd).

 The extrapolation and radiative boundary conditions have special cases for
 edges and corners. Thus they give incorrect results when applied on and
 edge or in a corner that is not a physical edge or corner. Thus I think
 the correct condition should be to remove the condition
 all_physbnd_or_ghostbnd, and to use the condition (have_bnd and
 any_physbnd and all_physbnd) in the end.

 Given the nature of this boundary condition, this means that symmetries
 need to be applied after this boundary condition, and one also needs to
 synchronise after applying this boundary condition. If this is done,
 errors on symmetry or ghost zones do not matter, which may make the
 noticed inconsistency in the code un-observable in practice.

 For safety, we may want to set all points that are (have_bnd and
 any_physbnd and not all_physbnd) to nan, because these are the outer
 boundary points that we did not set, and which thus need to be set by
 symmetries or synchronisation.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/1261#comment:3>
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