#12151: Bug in global_integral_model for elliptic curves over number fields
-------------------------------+--------------------------------------------
Reporter: johanbosman | Owner: cremona
Type: defect | Status: new
Priority: major | Milestone: sage-4.8
Component: elliptic curves | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by cremona):
This can be fixed by changing
{{{
for P, _ in K.ideal(a.denominator()).factor():
}}}
on line 564 of ell_number_field.py to
{{{
for P in [P for P,e in K.ideal(a).factor() if e<0]:
}}}
or alternatively (I think)
{{{
for P, _ in a.denominator_ideal().factor():
}}}
I checked that the first alternative works.
NB I also think that the line
{{{
pi = K.uniformizer(P,'positive')
}}}
should be
{{{
pi = K.uniformizer(P,'negative')
}}}
since we will divide by a power of pi and want to make sure that the model
stays integral at other primes. This does not matter in the example given
where the class number is 1 so each pi will be an actual generator of the
prime ideal.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12151#comment:1>
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