Opened 2 years ago

Closed 5 weeks ago

#26060 closed defect (fixed)

Wrong limit(x / (x + 2^x + cos(x)), x=-oo)

Reported by: pelegm Owned by:
Priority: major Milestone: sage-9.2
Component: calculus Keywords: limit, maxima
Cc: slelievre Merged in:
Authors: Samuel Lelièvre Reviewers: Karl-Dieter Crisman
Report Upstream: Fixed upstream, in a later stable release. Work issues:
Branch: 7f96496 (Commits) Commit: 7f964965cc53474166342bcf9a1146233d9fc42b
Dependencies: #26625 Stopgaps:

Description (last modified by slelievre)

Up to Sage 8.7 this limit returns "und" for "undefined":

sage: limit(x / (x + 2^x + cos(x)), x=-infinity)
und

while it should clearly be 1.

SymPy returns the correct result:

sage: limit(x / (x+2^x + cos(x)), x=-infinity, algorithm='sympy')
1

Reported to Maxima on 2018-08-15 as Maxima bug 3459, fixed there by Maxima commit 0c5c018 on 2018-08-30, fix included in Maxima 5.42.2 to which we upgrade in #26625, merged in Sage 8.8.beta7.

In Sage >= 8.8 we get the correct value for this limit:

sage: limit(x / (x + 2^x + cos(x)), x=-infinity)
1

This ticket adds a doctest for that limit computation.

Change History (19)

comment:1 Changed 2 years ago by kcrisman

  • Report Upstream changed from N/A to Reported upstream. No feedback yet.

Apparently yes.

$ sage --maxima
<snip>
Maxima 5.41.0 http://maxima.sourceforge.net
using Lisp ECL 16.1.2
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) limit(x / (x+2^x+cos(x)),x,-inf)       ;
(%o1)                                 und

I've reported this at Maxima bug 3459.

comment:2 Changed 2 years ago by kcrisman

  • Report Upstream changed from Reported upstream. No feedback yet. to Reported upstream. Developers acknowledge bug.

comment:3 Changed 2 years ago by kcrisman

  • Report Upstream changed from Reported upstream. Developers acknowledge bug. to Fixed upstream, but not in a stable release.

comment:4 Changed 2 years ago by kcrisman

(That was pretty fast work!)

comment:5 Changed 20 months ago by slelievre

  • Cc slelievre added
  • Dependencies set to #26625
  • Description modified (diff)
  • Keywords changed from limit,maxima to limit, maxima
  • Milestone changed from sage-8.4 to sage-8.7
  • Report Upstream changed from Fixed upstream, but not in a stable release. to Fixed upstream, in a later stable release.

After the upgrade to Maxima 5.42.2 in #26625, we should add a doctest here.

comment:6 Changed 19 months ago by embray

  • Milestone changed from sage-8.7 to sage-8.8

Ticket retargeted after milestone closed (if you don't believe this ticket is appropriate for the Sage 8.8 release please retarget manually)

comment:7 Changed 17 months ago by embray

  • Milestone sage-8.8 deleted

As the Sage-8.8 release milestone is pending, we should delete the sage-8.8 milestone for tickets that are not actively being worked on or that still require significant work to move forward. If you feel that this ticket should be included in the next Sage release at the soonest please set its milestone to the next release milestone (sage-8.9).

comment:8 Changed 2 months ago by mkoeppe

  • Milestone set to sage-duplicate/invalid/wontfix
  • Status changed from new to needs_review

Works in 9.2.beta10

comment:9 Changed 2 months ago by kcrisman

  • Status changed from needs_review to needs_work

Doctest

comment:10 Changed 6 weeks ago by slelievre

  • Branch set to public/ticket/26060
  • Commit set to 7f964965cc53474166342bcf9a1146233d9fc42b
  • Description modified (diff)
  • Status changed from needs_work to needs_review

Doctest added. Please review.


New commits:

7f9649626060: doctest for limit after Maxima upgrade

comment:11 Changed 6 weeks ago by slelievre

  • Milestone changed from sage-duplicate/invalid/wontfix to sage-9.2

comment:12 Changed 6 weeks ago by slelievre

  • Description modified (diff)

comment:13 Changed 6 weeks ago by slelievre

  • Summary changed from Wrong limit calculation to Wrong limit(x / (x + 2^x + cos(x)), x=-oo)

comment:14 Changed 6 weeks ago by kcrisman

Looks fine to me (assuming patchbot says it's fine), though all the other changes in typesetting could have occurred on another ticket. Thanks for doctesting!

comment:15 Changed 6 weeks ago by kcrisman

  • Status changed from needs_review to positive_review

comment:16 Changed 6 weeks ago by kcrisman

  • Authors set to Samuel Lelievre
  • Reviewers set to Karl-Dieter Crisman

comment:17 Changed 6 weeks ago by slelievre

  • Authors changed from Samuel Lelievre to Samuel Lelièvre

comment:18 Changed 6 weeks ago by kcrisman

Sorry! Haven't been keeping "Trac" as much lately.

comment:19 Changed 5 weeks ago by vbraun

  • Branch changed from public/ticket/26060 to 7f964965cc53474166342bcf9a1146233d9fc42b
  • Resolution set to fixed
  • Status changed from positive_review to closed
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