Opened 4 years ago

Closed 3 years ago

#23224 closed defect (fixed)

Doctest fix for: wrong symbolic comparison of log

Reported by: chapoton Owned by:
Priority: major Milestone: sage-8.2
Component: symbolics Keywords:
Cc: rws, mforets Merged in:
Authors: Ralf Stephan Reviewers: Marcelo Forets
Report Upstream: N/A Work issues:
Branch: 022656f (Commits, GitHub, GitLab) Commit: 022656f65ad89633328901771f76151c7f2f0503
Dependencies: #23950, #18970 Stopgaps:

Status badges

Description (last modified by rws)

Namely 

sage: bool(log(8)- 3*log(2))
True
sage: bool(log(8)==3*log(2))
False

compared to 

sage: cmp(log(8),3*log(2))
0

And cmp should be going away in python3.

In principle Maxima should simplify log(8)-3*log(2) so it's a missing enhancement there. See ​https://github.com/pynac/pynac/issues/258 for an enhancement that can provide another solution.

Change History (8)

comment:1 Changed 4 years ago by chapoton

  • Description modified (diff)

comment:2 Changed 4 years ago by rws

Factorization in GiNaC::log_eval, why not.

comment:3 Changed 4 years ago by rws

  • Description modified (diff)

comment:4 Changed 4 years ago by rws

  • Dependencies set to #23950
  • Milestone changed from sage-8.0 to sage-8.1

comment:5 Changed 3 years ago by rws

  • Branch set to u/rws/23224

comment:6 Changed 3 years ago by rws

  • Authors set to Ralf Stephan
  • Commit set to 022656f65ad89633328901771f76151c7f2f0503
  • Dependencies changed from #23950 to #23950, #18970
  • Status changed from new to needs_review
  • Summary changed from wrong symbolic comparison of log to Doctest fix for: wrong symbolic comparison of log

New commits:

​b0486c818970: Log function and documentation revamp
​022656f23224: doctests

comment:7 Changed 3 years ago by mforets

  • Milestone changed from sage-8.1 to sage-8.2
  • Reviewers set to Marcelo Forets
  • Status changed from needs_review to positive_review

branch tested on SageMath version 8.1.rc2

comment:8 Changed 3 years ago by vbraun

  • Branch changed from u/rws/23224 to 022656f65ad89633328901771f76151c7f2f0503
  • Resolution set to fixed
  • Status changed from positive_review to closed
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