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hannorein / rebound

💫 An open-source multi-purpose N-body code.
https://rebound.readthedocs.io/
GNU General Public License v3.0
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Collision Test Fix #746

Closed tigerchenlu98 closed 8 months ago

tigerchenlu98 commented 8 months ago

Hey Hanno, this one was quite tricky but think I figured it out!

1) Some issues with the scope of nbody_ode. After a merge (and seemingly only after a merge), only the local variable nbody_ode is updated, not the global r->odes[0]. To be honest I don't entirely understand why your code didn't work, everything looked fine to me - but I reassign y within the loop now and it seems to work.

2) Unrelated bug, but realized over the course of debugging that it's important to still update the actual r->t variable during the bs step. collision_resolve checks the last time of collision against the current simulation time, so this fails if the collision happens during the first call of bs_step.

hannorein commented 8 months ago

Amazing. Thank you! I don't understand it fully yet... will look at it tomorrow.

hannorein commented 8 months ago

Very well spotted! The issue was that when BS accepts a step, it overwrites the initial y array by swapping a pointer, rather than copying all the individual values (because it's faster). And yes, to the other issue regarding the time during collisions! Thank you!