Steven D'Aprano wrote: > On Fri, 23 Jun 2006 02:17:39 -0700, Filip Wasilewski wrote: > > > [EMAIL PROTECTED] wrote: > > > >> Logically, I should be able to enter x[-2:-0] to get the last and next to > >> last characters. However, since Python doesn't distinguish between > >> positive and negative zero, this doesn't work. Instead, I have to enter > >> x[-2:]. > > > > Hooray! Logically there is no such thing as positive or negative zero, > > or did I miss something in the primary? > > No, not in the primary, or even in the secondary, but possibly in the > tertiary. > > For many purposes, it doesn't make sense to distinguish +0 from -0. But > for other purposes, it does.
I believe you will agree that this is mostly a matter of notation of some fact rather than really trying to sign zero. For example I use to denote numbers that approach zero from "the right side" by x -> [0 uppercase +], which is definitely harder to type and display in poor man's text editor than x -> +0. Otherwise I should also rethink the meaning of positive (>0) and negative (<0) numbers (at least where such relations are defined). [...] > In statistical mechanics, some systems can have negative absolute > temperatures, including negative zero. Counter-intuitively, negative > absolute temperatures aren't colder than absolute zero, but hotter than > any positive temperature. So, strangely enough, a temperature of -0K is > hotter than a infinitely hot temperature! Yeah, this is really cool ;-) -- Filip "During board meeting: We have great news. Our earnings reached highest value ever - a positive 0." -- http://mail.python.org/mailman/listinfo/python-list
