Dear all, I hope you are well. It is me again pestering you all with questions or looking for advice :).
We are currently working on our DEM simulation engine using deal.II particles features. DEM lead to very chaotic systems (with positive Lyapunov exponents, like in MD), which means that slight discrepancies in floating point numbers can lead to exponentially different results. You can imagine for example that if a particle is to fall exactly on top of another, a slight difference in round-off error can lead to the particle sliding to the right or to the left of the other particle. Consequently, very small differences accumulate and lead to drastically different results. Right now, we are testing everything using numdiff within a ctest framework identical to deal.II. However, since we are comparing text files with particles positions and velocities, the tests end up being extremely fragile because they depend on the compiler version and MPI library being used (I guess?). I was wondering if any of you had experience on what would be the best way to write functional tests that test the full code in the context of systems which show highly chaotic behavior like this? Right now we try to test for very small time, thus ensuring that differences don't have the time to propagate, but this is becoming more and more fragile and sometimes tests will crash on a peculiar machine, yet work on 95% of the other ones (such as our github actions). Thanks and I wish you all great holidays! Bruno -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/22c85579-d403-4431-b150-e0520271df75n%40googlegroups.com.
