New submission from Jurjen N.E. Bos <j...@users.sourceforge.net>:
The documentation of math.sin (and related trig functions) doesn't speak about backward error. In cPython, as far as I can see, there is no backward error at all, which is quite uncommon. This may vary between implementations; many math libraries of other languages have a backward error, resulting in large errors for large arguments. e.g. sin(1<<500) is correctly computed as 0.42925739234242827, where a backward error as small as 1e-150 can give a completely wrong result. Some text could be added (which I am happy to produce) that explains what backward error means, and under which circumstances you can expect an accurate result. ---------- assignee: docs@python components: Documentation messages: 334672 nosy: docs@python, jneb priority: normal severity: normal status: open title: math.sin has no backward error; this isn't documented versions: Python 2.7, Python 3.4, Python 3.5, Python 3.6, Python 3.7, Python 3.8 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue35880> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
