In article <4de31635$0$29990$c3e8da3$54964...@news.astraweb.com>, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: >That's also completely wrong. The correct way to test for a NAN is with >the IEEE-mandated function isnan(). The NAN != NAN trick is exactly that, >a trick, used by programmers when their language or compiler doesn't >support isnan().
Perhaps it would be reasonable to be able to do: x.isnan() when x is a float. >Without support for isinf(), identifying an INF is just as hard as >identifying an NAN, and yet their behaviour under equality is the >complete opposite: > >>>> inf = float('inf') >>>> inf == inf >True Fortunately: def isnan(x): return x != x _inf = float("inf") def isinf(x): return x == _inf del _inf both do the trick here. I would like to have both modes (non-exception-ing and exception-ing) of IEEE-style float available in Python, and am not too picky about how they would be implemented or which one would be the default. Python could also paper over the brokenness of various actual implementations (where signalling vs quiet NaNs, and so on, do not quite work right in all cases), with some performance penalty on non-conformant hardware. -- In-Real-Life: Chris Torek, Wind River Systems Salt Lake City, UT, USA (40°39.22'N, 111°50.29'W) +1 801 277 2603 email: gmail (figure it out) http://web.torek.net/torek/index.html
-- http://mail.python.org/mailman/listinfo/python-list