Bug in saturation for elliptic curves over Q
|Reported by:||cremona||Owned by:|
|Authors:||John Cremona||Reviewers:||François Bissey|
|Report Upstream:||Fixed upstream, in a later stable release.||Work issues:|
Description (last modified by )
A bug in eclib's saturation function is revealed here:
sage: E = EllipticCurve([0,-1,1,-266,968]) sage: Q1 = E([-1995,3674,125]) sage: Q2 = E([157,1950,1]) sage: E.saturation([Q1,Q2]) ([(-399/25 : 3674/125 : 1), (157 : 1950 : 1)], 1, 7.21429780216482) sage: P1, P2 = E.gens() sage: E.regulator() 0.801588644684980 sage: E.regulator_of_points([Q1,Q2]) 7.21429780216482
The points Q1,Q2 generate a subgroup of index 3 but the computed bound on the index is between 2 and 3. This will be fixed upstream.
Note that for this curve E.gens() gives correct generators but E.simon_two_descent() gives the above two points.
New upstream source at http://boxen.math.washington.edu/home/cremona/eclib-20150323.tar.bz2
Change History (10)
comment:1 Changed 2 years ago by
- Report Upstream changed from Reported upstream. Developers acknowledge bug. to Fixed upstream, but not in a stable release.
comment:3 Changed 2 years ago by
- Report Upstream changed from Fixed upstream, but not in a stable release. to Fixed upstream, in a later stable release.
comment:5 Changed 2 years ago by
- Branch changed from u/cremona/18031 to u/cremona/eclib-18031
- Commit set to acefe94db857b8ae9de051203a5a61ff74df7d0c
comment:7 Changed 2 years ago by
- Reviewers set to François Bissey
- Status changed from needs_review to positive_review