#8003: EllipticCurve('522j1').sha().an_padic(13) fails
-------------------------------+--------------------------------------------
Reporter: rlm | Owner: cremona
Type: defect | Status: new
Priority: major | Milestone: sage-4.3.2
Component: elliptic curves | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
-------------------------------+--------------------------------------------
Description changed by rlm:
Old description:
> This is because the quadratic twist parameter `D` needs to be cast to an
> integer, but after the following patch it still fails.
> {{{
> diff -r 0133676998bd sage/schemes/elliptic_curves/sha_tate.py
> --- a/sage/schemes/elliptic_curves/sha_tate.py Tue Jan 19 10:28:48 2010
> -0800
> +++ b/sage/schemes/elliptic_curves/sha_tate.py Tue Jan 19 13:05:47 2010
> -0800
> @@ -424,7 +424,7 @@
> if Et.conductor() < Nmin and valuation(Et.conductor(),2)
> <= valuation(DD,2):
> Nmin = Et.conductor()
> Dmax = DD
> - D = Dmax
> + D = ZZ(Dmax)
> Et = self.E.quadratic_twist(D)
> lp = Et.padic_lseries(p)
> else :
> }}}
> This time the failure is:
> {{{
> sage: EllipticCurve('522j1').sha().an_padic(13)
> ---------------------------------------------------------------------------
> ValueError Traceback (most recent call
> last)
>
> /Users/rlmill/sage-4.3.1.rc1/devel/sage-main/<ipython console> in
> <module>()
>
> /Users/rlmill/sage-4.3.1.rc1/local/lib/python2.6/site-
> packages/sage/schemes/elliptic_curves/sha_tate.pyc in an_padic(self, p,
> prec, use_twists)
> 504 not_yet_enough_prec = True
> 505 while not_yet_enough_prec:
> --> 506 lps =
> lp.Dp_valued_series(n,quadratic_twist=D,prec=r+1)
> 507 lstar = [lps[0][r],lps[1][r]]
> 508 verbose("the leading terms : %s"%lstar)
>
> /Users/rlmill/sage-4.3.1.rc1/local/lib/python2.6/site-
> packages/sage/schemes/elliptic_curves/padic_lseries.pyc in
> Dp_valued_series(self, n, quadratic_twist, prec)
> 1038 E = self._E
> 1039 p = self._p
> -> 1040 lps = self.series(n, quadratic_twist=quadratic_twist,
> prec=prec)
> 1041
> 1042 # now split up the series in two lps = G + H * alpha
>
> /Users/rlmill/sage-4.3.1.rc1/local/lib/python2.6/site-
> packages/sage/schemes/elliptic_curves/padic_lseries.pyc in series(self,
> n, quadratic_twist, prec)
> 934 raise ValueError, "quadratic_twist (=%s) must
> be a fundamental discriminant of a quadratic field"%D
> 935 if gcd(D,self._p*self._E.conductor()) != 1:
> --> 936 raise ValueError, "quadratic twist (=%s) must be
> coprime to p (=%s) and the conductor of the curve (%s)
> "%(D,self._p,self._E.conductor())
> 937
> 938 p = self._p
>
> ValueError: quadratic twist (=-3) must be coprime to p (=13) and the
> conductor of the curve (174)
> }}}
New description:
This is because the quadratic twist parameter `D` needs to be cast to an
integer, but after [attachment:trac_8003-make_D_in_ZZ_only.patch] it still
fails:
{{{
sage: EllipticCurve('522j1').sha().an_padic(13)
---------------------------------------------------------------------------
ValueError Traceback (most recent call
last)
/Users/rlmill/sage-4.3.1.rc1/devel/sage-main/<ipython console> in
<module>()
/Users/rlmill/sage-4.3.1.rc1/local/lib/python2.6/site-
packages/sage/schemes/elliptic_curves/sha_tate.pyc in an_padic(self, p,
prec, use_twists)
504 not_yet_enough_prec = True
505 while not_yet_enough_prec:
--> 506 lps =
lp.Dp_valued_series(n,quadratic_twist=D,prec=r+1)
507 lstar = [lps[0][r],lps[1][r]]
508 verbose("the leading terms : %s"%lstar)
/Users/rlmill/sage-4.3.1.rc1/local/lib/python2.6/site-
packages/sage/schemes/elliptic_curves/padic_lseries.pyc in
Dp_valued_series(self, n, quadratic_twist, prec)
1038 E = self._E
1039 p = self._p
-> 1040 lps = self.series(n, quadratic_twist=quadratic_twist,
prec=prec)
1041
1042 # now split up the series in two lps = G + H * alpha
/Users/rlmill/sage-4.3.1.rc1/local/lib/python2.6/site-
packages/sage/schemes/elliptic_curves/padic_lseries.pyc in series(self, n,
quadratic_twist, prec)
934 raise ValueError, "quadratic_twist (=%s) must
be a fundamental discriminant of a quadratic field"%D
935 if gcd(D,self._p*self._E.conductor()) != 1:
--> 936 raise ValueError, "quadratic twist (=%s) must be
coprime to p (=%s) and the conductor of the curve (%s)
"%(D,self._p,self._E.conductor())
937
938 p = self._p
ValueError: quadratic twist (=-3) must be coprime to p (=13) and the
conductor of the curve (174)
}}}
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8003#comment:1>
Sage <http://www.sagemath.org>
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