[ET Trac] [Einstein Toolkit] #1995: McLachlan constraint tests fail

[Einstein Toolkit]

#1995: McLachlan constraint tests fail
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  Reporter:  hinder                 |       Owner:                                                   
      Type:  defect                 |      Status:  new                                              
  Priority:  critical               |   Milestone:  ET_2017_05                                       
 Component:  EinsteinToolkit thorn  |     Version:  development version                              
Resolution:                         |    Keywords:  McLachlan constraints tests compiler optimization
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Comment (by diener):

 I have added the optionlist I use on my laptop.

 After todays call I experimented with adding -fp-model precise and found
 that the problem disappeared. In order to investigate the sensitivity of
 this test to roundoff errors, I then used the Noise thorn to add noise to
 the initial data with an amplitude of 1e-6. The differences between
 running with -O2 with and without noise was of order a few times 1e-5.
 Similarly the differences bwetween running with -O2 -fp-model precise with
 and without noise was of the same order of magnitude. On the other hand
 the difference between running with -O2 with and without -fp-precise is of
 order unity. This points to (but probably doesn't prove it) that the test
 is not overly sensitive to roundoff error. Rather I think the -fp-model
 precise turns off the buggy optimization.

 I will now test Frank's suggestion.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/1995#comment:29>
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