[ET Trac] [Einstein Toolkit] #851: ReflectionSymmetry Interpolation Errors and WeylScal4

[Einstein Toolkit]

#851: ReflectionSymmetry Interpolation Errors and WeylScal4
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 Reporter:  tbode   |       Owner:  tbode              
     Type:  defect  |      Status:  new                
 Priority:  major   |   Milestone:  ET_2012_05         
Component:  Cactus  |     Version:  development version
 Keywords:          |  
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 There is an inconsistency in ReflectionSymmetry on whether a scalar can
 have a tensor parity tag that isn't unity (pseudoscalars).  In
 ReflectionSymmetry's apply.c, a scalar GF's tensorparity flag is taken
 into account, while in interpolation this is ignored.  In the ET Toolkit,
 this only effects those using the ET version of WeylScal4 since only
 Psi4i, Psi2i, and Psi0i have all been registered as scalars with
 tensorparity=-1. When interpolating, e.g. Psi4, onto a sphere for mode
 decomposition, the interpolated quantities have sign errors in Psi4i and
 give erroneous gravitational wave modes.

 This problem applies to both Maxwell release and current development
 branch. Symptoms reported to me by Jim Healy.  I would suggest backporting
 the resulting fix to Maxwell.

 Either ReflectionSymmetry's interpolation has to allow for
 tensorparity=-1, or apply.c's acceptance of tensorparity=-1 should be
 removed and WeylScal4's GFs reverted to manually specified parities.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/851>
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