#9322: bug in simon_two_descent for elliptic curves
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Reporter: cremona | Owner: AlexGhitza
Type: defect | Status: needs_work
Priority: major | Milestone: sage-4.7.2
Component: elliptic curves | Keywords: Simon
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by cremona):
Replying to [comment:6 zimmerma]:
> is there a way to get the output of the print commands from the ell.gp
script
> when it is called from within Sage? Even with a large value of
DEBUGLEVEL_ell, the output
> of those print statements does not appear in the Sage session, thus it
is difficult to debug.
>
> Paul
You can get a whole gp session logged to a file by setting
gp=Gp(logfile=foobar.txt'). But the code in gp-simon.py creates its own
gp instance without using the logfile option. In the short term, edit
line 38 of sage/sage/schemes/elliptic_curves/gp-simon.py to add the
logfile option. A better long-term solution would be to have a logfile
parameter to the two-descent function itself and pass that on.
By the way, there are new version of Simon's scripts which in Sage Days in
March (6 months ago!) I got working in a better way, using gp2c to convert
to C code. There was some reason which I now cannot remember why there
was a delay in getting this merged, and after 6 months I fear that the
patches we made then would no longer work. Damn. Anyway, I strongly
suggest if you have problem cases that you run the curves directly through
ell.gp (outside Sage) using the newest version of ell.gp from Simon's web
page, since you may be seeing a problem which has already been fixed.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9322#comment:7>
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