Opened 6 years ago

Last modified 6 months ago

#17878 new defect

Wrong answer for a simple limit

Reported by: vdelecroix Owned by:
Priority: critical Milestone: sage-6.6
Component: calculus Keywords: bug, limit
Cc: kcrisman Merged in:
Authors: Reviewers:
Report Upstream: Not yet reported upstream; Will do shortly. Work issues:
Branch: Commit:
Dependencies: Stopgaps:

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Description (last modified by vdelecroix)

As reported in ​ask.sagemath.org we have 

sage: f = exp(-x) / (2 + sin(x))
sage: f.limit(x=+infinity)
und

but it is clearly defined. And sympy gives the expected answer 

sage: import sympy
sage: sympy.limit(f,x,+oo)
0

Change History (5)

comment:1 Changed 6 years ago by vdelecroix

  • Description modified (diff)

comment:2 Changed 6 years ago by kcrisman

  • Cc kcrisman added
  • Component changed from symbolics to calculus

comment:3 Changed 6 years ago by vdelecroix

  • Description modified (diff)

comment:4 Changed 3 years ago by zimmerma

here is another example of wrong limit (thanks Manuel Eberl, here with Sage 8.2): 

sage: f=log(log(x + e^(log(x)*log(log(x)))))/log(log(log(x + e^x + log(x))))
sage: f.limit(x=+infinity)
0

The correct answer is 1. See ​https://sourceforge.net/p/maxima/bugs/3393/

comment:5 Changed 6 months ago by chapoton

  • Keywords limit added
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