Opened 2 years ago

Closed 21 months ago

#21801 closed defect (fixed)

incorrect summation

Reported by: kcrisman Owned by:
Priority: major Milestone: sage-8.0
Component: calculus Keywords:
Cc: Merged in:
Authors: Thierry Monteil Reviewers: Travis Scrimshaw
Report Upstream: Completely fixed; Fix reported upstream Work issues:
Branch: 4b525bb (Commits) Commit: 4b525bb059e2986d6c8cc6c822c1abca730e701c
Dependencies: Stopgaps:

Description

Reported here:

sage: sum(1/((n+1)*(2*n-1)), n, 0, 1000).n()
-0.205068171626375
sage: sum(1/((n+1)*(2*n-1)), n, 0, 10000).n()
-0.204618542543703
sage: sum(1/((n+1)*(2*n-1)), n, 0, 100000).n()  # seems to be converging
-0.204573546255870
sage: sum(1/((n+1)*(2*n-1)), n, 0, oo).n()      # but not to this number
-1.09345743518226

sage: sum(1/((n+1)*(2*n-1)), n, 0, oo)
2/3*log(2) - 14/9
sage: sum(1/((n+1)*(2*n-1)), n, 0, oo).n() - sum(1/((n+1)*(2*n-1)), n, 0, 10000).n()
-0.888838892638556

Change History (7)

comment:1 Changed 2 years ago by jhpalmieri

  • Report Upstream changed from Not yet reported upstream; Will do shortly. to Reported upstream. No feedback yet.

comment:2 Changed 2 years ago by kcrisman

  • Report Upstream changed from Reported upstream. No feedback yet. to Fixed upstream, but not in a stable release.

comment:3 Changed 21 months ago by tmonteil

  • Branch set to u/tmonteil/incorrect_summation

comment:4 Changed 21 months ago by tmonteil

  • Authors set to Thierry Monteil
  • Commit set to 7a36941ede54986bfa4dbc2b35d4aa3f0f8e693d
  • Milestone changed from sage-7.5 to sage-8.0
  • Report Upstream changed from Fixed upstream, but not in a stable release. to Completely fixed; Fix reported upstream
  • Status changed from new to needs_review

The fix seems to have entered Sage now. So i am just ading a doctest to prevent the bug to reappear.

comment:5 Changed 21 months ago by git

  • Commit changed from 7a36941ede54986bfa4dbc2b35d4aa3f0f8e693d to 4b525bb059e2986d6c8cc6c822c1abca730e701c

Branch pushed to git repo; I updated commit sha1. New commits:

4b525bb#21801 : a doctest to prevent the bug to reappear.

comment:6 Changed 21 months ago by tscrim

  • Reviewers set to Travis Scrimshaw
  • Status changed from needs_review to positive_review

LGTM.

comment:7 Changed 21 months ago by vbraun

  • Branch changed from u/tmonteil/incorrect_summation to 4b525bb059e2986d6c8cc6c822c1abca730e701c
  • Resolution set to fixed
  • Status changed from positive_review to closed
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