Opened 12 years ago
Closed 12 years ago
#8942 closed defect (fixed)
failing calculation with limit
Reported by: | casamayou | Owned by: | burcin |
---|---|---|---|
Priority: | minor | Milestone: | sage-4.5.2 |
Component: | calculus | Keywords: | limit |
Cc: | jason, mvngu, mhansen | Merged in: | sage-4.5.2.alpha0 |
Authors: | Karl-Dieter Crisman | Reviewers: | Paul Zimmermann |
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description
In all three calculations below, the first result is false, whereas in a previous version of Sage, he returned Und what is the correct answer.
sage:f(x) = (cos(pi/4-x) - tan(x)) / (1 - sin(pi/4+x)) sage:limit(f(x), x = pi/4) +Infinity sage: limit(f(x), x = pi/4, dir='plus') -Infinity sage: limit(f(x), x = pi/4, dir='minus') +Infinity
Attachments (1)
Change History (8)
comment:1 follow-up: ↓ 2 Changed 12 years ago by
- Cc jason added
comment:2 in reply to: ↑ 1 Changed 12 years ago by
- Resolution set to fixed
- Status changed from new to closed
Replying to kcrisman:
This was fixed when we improved our recognition of Maxima's unsigned infinity.
sage: sage: limit(f(x), x = pi/4, dir='minus') +Infinity sage: sage: limit(f(x), x = pi/4, dir='plus') -Infinity sage: sage:limit(f(x), x = pi/4) InfinitySo I guess this can be closed? Or should we whip up a patch to document this...?
This can be closed. Thanks a lot !
comment:3 Changed 12 years ago by
- Cc mvngu mhansen added
- Resolution fixed deleted
- Status changed from closed to new
Thanks. One thing to point out is http://www.sagemath.org/doc/developer/trac.html#closing-tickets, so that in theory only the release manager should close a ticket. For instance, we might want to document this somewhere (which is what I was really asking about).
I will now violate that same web page by re-opening it; since it hasn't actually been merged (nothing to merge) hopefully that is ok, Minh or Mike :)
comment:4 Changed 12 years ago by
- Status changed from new to needs_review
If we want more documentation that we have fixed this, here it is. Ready for review.
comment:5 Changed 12 years ago by
- Status changed from needs_review to positive_review
positive review (I've checked that all doctests still pass).
A small comment: maybe the documentation could say more explicitly that the output Infinity
indicates a complex infinity, whereas +Infinity
means plus infinity.
By the way, there is a problem since Sage parses Infinity
as +Infinity
:
sage: Infinity +Infinity sage: Infinity == +Infinity True sage: a=limit(1/x, x=0) sage: a == +Infinity True
but this could be in a different ticket.
comment:6 Changed 12 years ago by
but this could be in a different ticket.
see #9480
comment:7 Changed 12 years ago by
- Merged in set to sage-4.5.2.alpha0
- Resolution set to fixed
- Reviewers set to Paul Zimmermann
- Status changed from positive_review to closed
This was fixed when we improved our recognition of Maxima's unsigned infinity.
So I guess this can be closed? Or should we whip up a patch to document this...?