yade-dev team mailing list archive

[Anton Gladky <gladky.anton@xxxxxxxxx>]

Hi Bruno,

thanks for the catch and for the fix. This commit was pushed
into the frozen Debian to have it fixed in Stretch [1].

[1] https://tracker.debian.org/news/843733

Best regards

Anton


2017-04-14 12:28 GMT+02:00 Bruno Chareyre <bruno.chareyre@xxxxxxxxxxxxxxx>:
> Hello all,
> A recent commit [1] fixed a critical bug of contact detection in periodic
> boundary conditions. All simulations with periodic conditions are
> potentially affected.
> I strongly suggest an update for everyone using periodic boundaries.
>
> I know personally at least four users who suffered from this bug over the
> last six years, I imagine many more have had the same problem without
> understanding it.
> Typically, a periodic simulation would crash in a (seemingly)
> non-deterministic way, after hours or days of simulations. It was actually
> the consequence of having one or more particle inside another, because the
> contact between them was missed (hence if you have unexplained crashes, stop
> the simulation right before it and check if you find particles overlapping
> too much).
>
> The logic of periodic sorting is so involved (I'm glad Vaçlav invented it)
> that I don't dare trying to explain the problem in details. The short story:
> in contrast with the non-periodic case sorting elements of a periodic ring
> can't be done in N steps (at least with our algorithm, N being the number of
> elements). As it was the case before the fix the list of positions was left
> partially un-ordered.
>
> Cheers.
>
> Bruno
>
> [1]
> https://github.com/yade/trunk/commit/c7c8e6f62d452c81a31415f05a12587a6cc8c452
>
>
>
> --
>
> _______________
> Bruno Chareyre
> Associate Professor
> ENSE³ - Grenoble INP
> Lab. 3SR
> BP 53
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> Tél : +33 4 56 52 86 21
> Fax : +33 4 76 82 70 43
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