#13065: simon_two_descent not working
-----------------------------------------------------------+----------------
Reporter: alexc | Owner:
cremona
Type: defect | Status:
needs_review
Priority: major | Milestone:
sage-5.4
Component: elliptic curves | Resolution:
Keywords: EllipticCurve simon_two_descent gp pari | Work issues:
Report Upstream: Reported upstream. No feedback yet. | Reviewers:
Authors: Francis Clarke | Merged in:
Dependencies: | Stopgaps:
-----------------------------------------------------------+----------------
Old description:
> 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.
New description:
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.
'''Apply''':
* [attachment:trac_13065_simon_two_descent-replacement.patch]
--
Comment (by fwclarke):
Replying to [comment:10 cremona]:
> PS The full test worked without a hitch so perhaps I was unnecessarily
cautious (about deleting the line which defines x).
It looks as though that line has been there from the beginning (sage-2.6).
> This just leaves adding a comment about the version of the scripts which
cause that error.
I've replaced the patch with one that refers to the version.
> What then with this ticket? I cannot exactly be closed since the error
has not been fixed, just flagged better. Perhaps the thing to do is to
close this ticket but to open a similar one which refers back to this one.
Seems like a good idea. From the point of view of Sage, the error was in
the implementation of reporting errors in the script(s) (plus one or two
other things). A new ticket could (re-)document the upstream report.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13065#comment:11>
Sage <http://www.sagemath.org>
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and MATLAB
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