[ET Trac] [Einstein Toolkit] #747: 9th order prolongation test fails with REAL_PRECISION=4

[Einstein Toolkit]

#747: 9th order prolongation test fails with REAL_PRECISION=4
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  Reporter:  hinder  |       Owner:  eschnett
      Type:  defect  |      Status:  new     
  Priority:  major   |   Milestone:          
 Component:  Carpet  |     Version:          
Resolution:          |    Keywords:          
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Comment (by eschnett):

 I don't think changing things to an L1 warning is a good solution. Either
 9th order prolongation works with single precision (then we fix it), or it
 doesn't because of lack of precision (then we disable it). Or maybe we
 just have to lower our expectations with single precision.

 For example, the statement

 if (not (good::abs (res - y0) < 1.0e-12))

 may need adjusting. Replacing 1.0e-12 by eps^(3/4) where eps is the
 precision of CCTK_REAL may be a way.

 RT is a type; it is the real type corresponding to T, which may be a
 complex type. In C++, eps = numeric_limits<RT>::min(). Can you check
 whether eps^(3/4) works for single precision? 1.5e-5 seems borderline for
 this.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/747#comment:1>
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