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by RyJones 60 days ago
Interesting: https://youtu.be/cb5r3r38O9c

Guy's world records get deleted due to changes in atanh over time

2 comments

As that's a pretty long video would you mind giving a short summary of what happened? Was it a world record in a game?
yeah one of the trackmania games -- which feature a nominally deterministic physics engine, allowing for replays from a recorded sequence of inputs... except the physics engine relies on libc transcendental functions. players are generally on windows, but backend servers doing anti-cheat validations via replays are running linux. this resulted in false cheat positives when the linux server was running glibc prior to the glibc rounding fixes... and as a result the guy's world record kept being flagged as a cheat. it's a pretty good video with a lot of detail on how they narrowed it down to specific glibc versions/etc.
Pretty sure that's atan.