#14060: Some elliptic curve functions fail since pari_curve is created with
insufficient precision
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Reporter: cremona | Owner: cremona
Type: defect | Status: new
Priority: major | Milestone: sage-5.8
Component: elliptic curves | Keywords: pari precision
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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This fails on a 32-bit machine (Sage-5.6):
{{{
sage: EllipticCurve([0, -1, 0, -360796668980,
83414685883377400]).minimal_quadratic_twist()
}}}
because it results in pari_curve() being called on some curves with no
attempt to catch insufficient precision.
Two things needs fixing: (1) Making sure that all calls to pari_curve()
deal with this precision issue properly; (2) a better implementation of
minimal_quadratic_twist(), for example if the conductor is square-free
then there is no need to do so much rwork as is currently done.
Additionally, when j(E)=0 or 1728 the curve returned is a minimal twist,
but not necessarily a quadratic twist, so the documentation (or function
name, or something) needs correcting.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14060>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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