[ET Trac] [Einstein Toolkit] #1599: CarpetInterp/waveinterp_2p tests constant in time initial data

[Einstein Toolkit]

#1599: CarpetInterp/waveinterp_2p tests constant in time initial data
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 Reporter:  rhaas         |       Owner:  eschnett           
     Type:  defect        |      Status:  new                
 Priority:  minor         |   Milestone:                     
Component:  Carpet        |     Version:  development version
 Keywords:  CarpetInterp  |  
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 the test waveinterp_2p sets up initial data using IDWaveMoL (fom
 CactusExamples) using kx=ky=kz = 0. and slopet = 0.1. Ie the initial data
 is constant in space and has frequency 0.1. It then evolves this using
 WaveMoL and interpolates in space and time with CarpetInterp.

 Since the function is constant in space (exactly so, see eg the output in
 InterpToArray::array1d_vars[0]) the interpolation in space just tests
 roundoff errors. The second time derivative (array1d_vars[2]) should be
 zero and all we measure in the test is truncation errors on the level of
 1e-9. This makes the test very sensitive to -Ofast, -O0, gcc vs. intel
 etc. and not a very good test.

 I would rather either use a Gausian wave for initial data so that there is
 some actual data in the result and not just numerical noise, or leave out
 the 2nd time derivative from the test data.

 The test fails due to significant errors in a virtual machine using
 ubuntu.cfg (which usies -ffast-math and -O2).

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/1599>
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