=?ISO-8859-1?Q?=22Martin_v=2E_L=F6wis=22?= <[EMAIL PROTECTED]> wrote: > > Ah, you are proposing a semantic change, then: -0.0 will become > unrepresentable, right?
Well, it is and it isn't. Python currently supports only some of IEEE 754, and that is more by accident than design - because that is exactly what C90 implementations do! There is code in floatobject.c that assumes IEEE 754, but Python does NOT attempt to support it in toto (it is not clear if it could), not least because it uses C90. And, as far as I know, none of that is in the specification, because Python is at least in theory portable to systems that use other arithmetics and there is no current way to distinguish -0.0 from 0.0 except by comparing their representations! And even THAT depends entirely on whether the C library distinguishes the cases, as far as I can see. So distinguishing -0.0 from 0.0 isn't really in Python's current semantics at all. And, for reasons that we could go into, I assert that it should not be - which is NOT the same as not supporting branch cuts in cmath. Regards, Nick Maclaren, University of Cambridge Computing Service, New Museums Site, Pembroke Street, Cambridge CB2 3QH, England. Email: [EMAIL PROTECTED] Tel.: +44 1223 334761 Fax: +44 1223 334679 _______________________________________________ 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
