OK, a bit more work & two things cleared up. This was just dumb on my part:
> limit(1/x, x=0) is unsigned_infinity That should definitely be False, no disagreement there. I had misunderstood the meaning of the word "is". (Insert political joke here.) Further, this behavior actually makes sense: > limit(1/x, x=0) == unsigned_infinity True This one still doesn't make sense to me, though: > limit(1/x, x=0) == Infinity Infinity == +Infinity I'll grant that that's not a True statement, but shouldn't a typed Infinity represent unsigned_infinity, rather than +Infinity? (And either way, shouldn't the documentation for limit() say something about this?) john perry On Wednesday, June 8, 2016 at 2:15:13 PM UTC+3, john_perry_usm wrote: > > Thank you! Still, the following behavior is awfully confusing to me: > > > unsigned_infinity > Infinity > > unsigned_infinity is Infinity > False > > Infinity is +Infinity > True > > limit(1/x, x=0) is unsigned_infinity > False > > (limit(1/x, x=0) == +Infinity).full_simplify() > 1 > > I'd think the the answers after the first line should read True, False, > True, 0. Instead, I get their opposites. > > john perry > > On Wednesday, June 8, 2016 at 9:55:36 AM UTC+3, Ralf Stephan wrote: >> >> Yes Maxima's unsigned inf is converted to Sage's unsigned inf. >> And: >> >> sage: unsigned_infinity >> Infinity >> >> versus >> >> sage: +Infinity >> +Infinity >> >> So you really got unsigned inf first. BTW, SymPy names it zoo which I >> like. >> >> On Wednesday, June 8, 2016 at 6:48:48 AM UTC+2, john_perry_usm wrote: >>> >>> I decided to dig further. Maxima's documentation >>> <http://maxima.sourceforge.net/docs/manual/maxima_singlepage.html#SEC93> >>> contains information that Sage's docs lack: >>> >>> infinity (complex infinity) is returned when the limit of the absolute >>>> value of the expression is positive infinity, but the limit of the >>>> expression itself is not positive infinity or negative infinity. >>>> >>> >>> That explains it. I guess that if a Maxima user sees infinity, then >>> s/he knows to do something more to resolve whether it's inf or minf. >>> But: >>> >>> 1. Should Sage's documentation include this, as well? >>> 2. Is there some way in Sage to distinguish Maxima's complex >>> infinity from Sage's +infinity, the way Maxima itself does? >>> >>> >>> -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
