#8820: elliptic_exponential broken for curves over number fields
----------------------------------------------+-----------------------------
Reporter: robertwb | Owner: cremona
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.6
Component: elliptic curves | Keywords:
Author: John Cremona | Upstream: N/A
Reviewer: Chris Wuthrich, Jeroen Demeyer | Merged:
Work_issues: |
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Comment(by jdemeyer):
Also, there is trouble with points which are very close to the point af
infinity:
{{{
sage: K.<a> = QuadraticField(-1)
sage: E = EllipticCurve([0,0,0,a,0])
sage: L = E.period_lattice(K.complex_embeddings()[0])
sage: L.elliptic_exponential(1e-100)
---------------------------------------------------------------------------
PariError Traceback (most recent call
last)
/home/jdemeyer/<ipython console> in <module>()
/usr/local/src/sage-4.6.alpha1/local/lib/python2.6/site-
packages/sage/schemes/elliptic_curves/period_lattice.pyc in
elliptic_exponential(self, z, to_curve)
1527 # the same precision as the input.
1528
-> 1529 x,y = pari(self.basis(prec=prec)).ellwp(w,flag=1)
1530 x,y = [C(t) for t in (x,y)]
1531
/usr/local/src/sage-4.6.alpha1/local/lib/python2.6/site-
packages/sage/libs/pari/gen.so in sage.libs.pari.gen._pari_trap
(sage/libs/pari/gen.c:45047)()
PariError: division by zero (27)
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8820#comment:24>
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