Michael Felt <aixto...@felt.demon.nl> added the comment:
I have been doing a lot of research on this. Wish I had thought do start the way I finished. Basically, when math.nextafter() was added all the AIX bots were on systems running AIX earlier than AIX 7.2 TL2. When AIX 7.2 TL2 was released (roughly Q3 2017) a (major?) change was made to the nextafter() function. root@gcc119:[/home2/root]instfix -k IV95512 -a IV95512 Abstract: nextafter(+0.0, -0.0) returns +0.0 instead of -0.0. IV95512 Symptom Text: If(x==y) nextafter returns x instead of y. At first glance - it appears the CPython code is reversing the arguments: The lines in test_math.py are currently: +2026 # NaN +2027 self.assertIsNaN(math.nextafter(NAN, 1.0)) +2028 self.assertIsNaN(math.nextafter(1.0, NAN)) +2029 self.assertIsNaN(math.nextafter(NAN, NAN)) Moving line 2027 (which is what is failing) to 2029 - the other two lines pass on an AIX system with IV95512 applied. As IEEE754 says (and seems to have always said): https://pubs.opengroup.org/onlinepubs/9699919799: If x or y is NaN, a NaN shall be returned. The current test in Modules/mathmodule.c might be too simple. I am working on a PR where I check for presence of APAR IV95512 - with the nextafter() changes. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue42323> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
