#13065: simon_two_descent not working
-------------------------------+--------------------------------------------
Reporter: alexc | Owner: cremona
Type: defect | Status: new
Priority: major | Milestone: sage-5.0.1
Component: elliptic curves | Keywords: EllipticCurve
simon_two_descent gp pari
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
-------------------------------+--------------------------------------------
In certain cases simon_two_descent produces an error. For example:
{{{
----------------------------------------------------------------------
| Sage Version 5.0, Release Date: 2012-05-14 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
sage: poly = CyclotomicField(43).subfields(3)[0][0].polynomial()
sage: poly
x^3 + x^2 - 14*x + 8
sage: K = NumberField(poly, 'a')
sage: E = EllipticCurve(K, '37')
sage: E
Elliptic Curve defined by y^2 + y = x^3 + (-1)*x over Number Field in
a with defining polynomial x^3 + x^2 - 14*x + 8
sage: E.simon_two_descent()
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/home/blatm/<ipython console> in <module>()
/home/blatm/sage/sage-5.0-linux-64bit-ubuntu_10.04.3_lts-x86_64-Linux/
local/lib/python2.7/site-packages/sage/schemes/elliptic_curves/
ell_number_field.pyc in simon_two_descent(self, verbose, lim1, lim3,
limtriv, maxprob, limbigprime)
281 verbose=verbose, lim1=lim1,
lim3=lim3, limtriv=limtriv,
282 maxprob=maxprob,
limbigprime=limbigprime)
--> 283 prob_rank = Integer(t[0])
284 two_selmer_rank = Integer(t[1])
285 prob_gens = [self(P) for P in t[2]]
/home/blatm/sage/sage-5.0-linux-64bit-ubuntu_10.04.3_lts-x86_64-Linux/
local/lib/python2.7/site-packages/sage/rings/integer.so in
sage.rings.integer.Integer.__init__ (sage/rings/integer.c:6865)()
TypeError: unable to convert x (=f) to an integer
}}}
I have tried Simon's scripts in gp directly, and this case fails there as
well:
{{{
sage: gp.console()
Reading GPRC: /home/blatm/sage/sage-5.0-linux-64bit-
ubuntu_10.04.3_lts-x86_64-Linux/local/etc/gprc.expect ...Done.
GP/PARI CALCULATOR Version 2.5.1 (development git-5c5e253)
amd64 running linux (x86-64/GMP-5.0.2 kernel) 64-bit version
compiled: May 14 2012, gcc-4.6.3 (GCC)
(readline v6.2 enabled, extended help enabled)
Copyright (C) 2000-2011 The PARI Group
PARI/GP is free software, covered by the GNU General Public License, and
comes
WITHOUT ANY WARRANTY WHATSOEVER.
Type ? for help, \q to quit.
Type ?12 for how to get moral (and possibly technical) support.
parisize = 8000000, primelimit = 500509
? \r ~/pari/pari-2.5.1/examples/ell.gp \\This is Simon's 2-descent script,
taken from his webpage.
? K = bnfinit(y^3+y^2-14*y+8);
? E37A = [0,0,1,-1,0];
? bnfellrank(K,E37A)
*** at top-level: bnfellrank(K,E37A)
*** ^------------------
*** in function bnfellrank: ...eqtheta,rnfeq,bbnf];rang=
*** bnfell2descent_gen(b
*** ^--------------------
*** in function bnfell2descent_gen: ...und,r=nfsqrt(nf,norm(zc))
*** [1];if(DEBUGLEVEL_el
*** ^--------------------
*** array index (1) out of allowed range [none].
?
}}}
I am running Sage 5.0 on Ubuntu 11.04 64bit.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13065>
Sage <http://www.sagemath.org>
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