Steven D'Aprano <steve+pyt...@pearwood.info> added the comment: I've done some spot checks of NormDist.pdf and .cdf and compared the results to those returned by my TI Nspire calculator.
So far, the PDF has matched that of the Nspire to 12 decimal places (the limit the calculator will show), but the CDF differs on or about the 8th decimal place: py> x = statistics.NormalDist(2, 1.3) py> x.cdf(5.374) 0.9952757439207682 # Nspire normCdf(-∞, 5.372, 2, 1.3) returns 0.995275710979 # difference of 3.294176820212158e-08 py> x.cdf(-0.23) 0.04313736707891003 # Nspire normCdf(-∞, -0.23, 2, 1.3) returns 0.043137332077 # difference of 3.500191003008579e-08 Wolfram Alpha doesn't help me decide which is correct, as it doesn't show enough decimal places. https://www.wolframalpha.com/input/?i=CDF[+NormalDistribution[2,+1.3],+5.374+] https://www.wolframalpha.com/input/?i=CDF[+NormalDistribution[2,+1.3],+-0.23+] Do we care about this difference? Should I raise a new ticket for it? ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue36018> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
