Clearly I'm the one to answer this. Firstly, by typing "sage -mwrank -h" you can see the command-line option for mwrank, which tells you something. But not in fact enough. If you set EE=E.mwrank_curve() and then look at the docstring for EE.two_descent() it will explain more. When doing a 2-descent one first constructs homogeneous spaces and then searches for points on them; there are bounds used for this search. The second bound is only relevant for curves with a 2-torsion point, where we do a descent via 2-isogeny followed by a second descent, and there are separate searches for each stage.
Some of these docstrings should be improved, or at least some cross-referencing inserted (otherwise there would be a lot of repetition since many other functions call this two_descent one). John PS Ifti, feel free to ask me for more details off-list. On 22 January 2012 16:02, Iftikhar Burhanuddin <iftikhar.burhanud...@gmail.com> wrote: > Hi folks, > > Let E be an elliptic curve over QQ in Sage. What is the > descent_second_limit parameter in the E.gens method? > > The doc string states the following. > > ``descent_second_limit`` - (default: 12)- used in 2-descent > > IMPLEMENTATION: Uses Cremona's mwrank C library. > > Regards, > Ifti > > -- > You received this message because you are subscribed to the Google Groups > "sage-nt" group. > To post to this group, send an email to sage...@googlegroups.com. > To unsubscribe from this group, send email to > sage-nt+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sage-nt?hl=en-GB. > -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
