On Jan 29, 2015, at 6:52 AM, Steven D'Aprano That's essentially the same as Bruce Dawson recommends:
If anyone's interested in playing with this, I updated my sample implementation with a flag that let's you select which method it will use. Four! options. Note that I not suggesting such a flag be there in an std lib function, but it makes it easy to experiment. https://github.com/PythonCHB/close_pep/blob/master/is_close_to.py Note that I found that every single one of my test cases passed with all four methods, except one designed specifically to demonstrate the asymmetry of the asymmetric test. Which was my point about it not mattering much in practice. I still need to add a bunch more to the PEP by way of explanation, then I hope to be able to gauge where people are at. -Chris