incorrect summation

[kcrisman]

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

Upstream: Completely fixed; Fix reported upstream

Component: calculus

Author: Thierry Monteil

Branch/Commit: 4b525bb

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/21801

[jhpalmieri]

comment:1

Tracked upstream at https://sourceforge.net/p/maxima/bugs/3236/.

[jhpalmieri]

Changed upstream from Not yet reported upstream; Will do shortly. to Reported upstream. No feedback yet.

[kcrisman]

Changed upstream from Reported upstream. No feedback yet. to Fixed upstream, but not in a stable release.

[sagetrac-tmonteil]

Branch: u/tmonteil/incorrect_summation

[sagetrac-tmonteil]

comment:4

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

[sagetrac-tmonteil]

Commit: 7a36941

[sagetrac-tmonteil]

Author: Thierry Monteil

[sagetrac-tmonteil]

Changed upstream from Fixed upstream, but not in a stable release. to Completely fixed; Fix reported upstream