On Tue, Oct 19, 2010 at 5:33 PM, Dr. David Kirkby
<david.kir...@onetel.net> wrote:
> On 10/20/10 12:07 AM, Justin C. Walker wrote:
>>
>> On Oct 17, 2010, at 17:50 , gagan wrote:
>>
>>> sage: E=EllipticCurve('11a1');
>>> sage: E.modular_degree();
>>> /Applications/sage/local/bin/sympow: line 3: 9922 Segmentation
>>> fault ./sympow $*
>>
>> I can't reproduce this problem (Mac OS X, 10.6.4, Dual Quad Xeon) using
>> 4.4, 4.5.2, 4.5.3, or 4.6.a3.
>>
>> Justin
>>
>> --
>> Justin C. Walker, Curmudgeon at Large
>> Director
>> Institute for the Enhancement of the Director's income
>
> Same here - I can't reproduce it (OpenSolaris on Xeon processor).
>
> Based on an inspection of the source code for SYMPOW, it is the worst I've
> seen in Sage. In fact, it's the worst code I have ever seen. So I personally
> would not be surprised if there are bugs in it.
And amazingly it is the best algorithm for computing modular
degrees... one of the most impressive algorithms I've ever seen.
Anyway, you'll be happy to know the author of SYMPOW now works
fulltime on Magma, so luckily you won't have to look at his code
anymore, since it stays hidden in a closed source system...
William
>
> That said, both John and William use the code for computing the modular
> degree of elliptic curves.
>
> There is a trac ticket open for implementing the Watkins-Delaunay's
> algorithm for computing modular degrees in Sage
>
> http://trac.sagemath.org/sage_trac/ticket/9758
>
> If there is a bug in the code, good luck finding it, as the code is almost
> obfuscated.
>
> Dave
>
> --
> To post to this group, send email to sage-support@googlegroups.com
> To unsubscribe from this group, send email to
> sage-support+unsubscr...@googlegroups.com
> For more options, visit this group at
> http://groups.google.com/group/sage-support
> URL: http://www.sagemath.org
>
--
William Stein
Professor of Mathematics
University of Washington
http://wstein.org
--
To post to this group, send email to sage-support@googlegroups.com
To unsubscribe from this group, send email to
sage-support+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sage-support
URL: http://www.sagemath.org
