#1995: McLachlan constraint tests fail ------------------------------------+--------------------------------------- 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 ------------------------------------+---------------------------------------
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.