#19091: eclib upgrade to version 20150826 (bugfix)
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Reporter: cremona | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.9
Component: packages: standard | Resolution:
Keywords: mwrank elliptic curves | Merged in:
Authors: John Cremona | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by cremona):
After:
{{{
sage: "Warning" in mwrank("[0, 0, 0, -532, -4374]")
False
}}}
{{{
sage: E = EllipticCurve( [0, 0, 0, -532, -4374])
sage: E.rank()
Unable to compute the rank with certainty (lower bound=1).
This could be because Sha(E/Q)[2] is nontrivial.
Try calling something like two_descent(second_limit=13) on the
curve then trying this command again. You could also try rank
with only_use_mwrank=False.
}}}
This may not look good, but mwrank is unable to compute the rank in this
case since there 2-Selmer rank is 3 while the Mordell-Weil rank is in fact
1 (as can be checked independently, either by computing the analytic rank:
{{{
sage: E.rank(only_use_mwrank=False)
1
}}}
or by using 3-descent -- not available in Sage, sadly.
--
Ticket URL: <http://trac.sagemath.org/ticket/19091#comment:2>
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