[EMAIL PROTECTED] > If C90 doesn't distinguish -0.0 and +0.0, how can Python?
With liberal applications of piss & vinegar ;-) > Can you give a simple example where the difference between the two is apparent > to the Python programmer? Perhaps surprsingly, many (well, comparatively many, compared to none ....) people have noticed that the platform atan2 cares a lot: >>> from math import atan2 as a >>> z = 0.0 # postive zero >>> m = -z # minus zero >>> a(z, z) # the result here is actually +0.0 0.0 >>> a(z, m) 3.1415926535897931 >>> a(m, z) # the result here is actually -0.0 0.0 >>> a(m, m) -3.1415926535897931 It work like that "even on Windows", and these are the results C99's 754-happy appendix mandates for atan2 applied to signed zeroes. I've even seen a /complaint/ on c.l.py that atan2 doesn't do the same when z = 0.0 is replaced by z = 0 That is, at least one person thought it was "a bug" that integer zeroes didn't deliver the same behaviors. Do people actually rely on this? I know I don't, but given that more than just 2 people have remarked on it seeming to like it, I expect that changing this would break /some/ code out there. BTW, on /some/ platforms all those examples trigger EDOM from the platform libm instead -- which is also fine by C99, for implementations ignoring C99's optional 754-happy appendix. _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
