On Wed, 31 May 2023, at 4:11 PM, Juan Nunez-Iglesias wrote: > For me it is indeed too surprising, and I would be in favour of reverting.
(👆 Incidentally I wrote that before seeing https://github.com/scikit-image/scikit-image/pull/6970 😂) > On Wed, 31 May 2023, at 3:55 PM, Sebastian Berg wrote: >> Hi all, >> >> there was recently a PR to NumPy to improve the performance of sin/cos >> on most platforms (on my laptop it seems to be about 5x on simple >> inputs). >> This changes the error bounds on platforms that were not previously >> accelerated (most users): >> >> https://github.com/numpy/numpy/pull/23399 >> >> The new error is <4 ULP similar to what it was before, but only on high >> end Intel CPUs which not users would have noticed. >> And unfortunately, it is a bit unclear whether this is too disruptive >> or not. >> >> The main surprise is probably that the range of both does not include 1 >> (and -1) exactly with this and quite a lot of downstream packages >> noticed this and needed test adaptions. >> >> Now, most of these are harmless: users shouldn't expect exact results >> from floating point math and test tolerances need adjustment. OTOH, >> sin/cos are practically 1/-1 on a wide range of inputs (they are >> basically constant) so it is surprising that they deviate from it and >> never reach 1/-1 exactly. >> >> Since quite a few downstream libs notice this and NumPy users cannot >> explicitly opt-in to a different performance/precision trade-off. The >> question is how everyone feels about it being better to revert for now >> and hope for a better one? >> >> I doubt we can decide on a very clear cut yes/no, but I am very >> interested what everyone thinks whether this precision trade-off is too >> surprising to users? >> >> Cheers, >> >> Sebastian >> >> >> _______________________________________________ >> NumPy-Discussion mailing list -- numpy-discussion@python.org >> To unsubscribe send an email to numpy-discussion-le...@python.org >> https://mail.python.org/mailman3/lists/numpy-discussion.python.org/ >> Member address: j...@fastmail.com > _______________________________________________ > NumPy-Discussion mailing list -- numpy-discussion@python.org > To unsubscribe send an email to numpy-discussion-le...@python.org > https://mail.python.org/mailman3/lists/numpy-discussion.python.org/ > Member address: j...@fastmail.com _______________________________________________ NumPy-Discussion mailing list -- numpy-discussion@python.org To unsubscribe send an email to numpy-discussion-le...@python.org https://mail.python.org/mailman3/lists/numpy-discussion.python.org/ Member address: arch...@mail-archive.com
