After debugging this I saw the problem. In sha_tate.py:410 you consider the first derivative non-zero and use it in computations, while in practice it is zero (e-15 vs error_bound=e-25).
On Wed, Oct 16, 2013 at 10:56:27AM +0100, John Cremona wrote: > We have theory that tells us that for curves of analytic rank 0 or 1, > Sha is finite and while BSD is not completely proved for such curves, > the formula it claims for #Sha is certainly rational -- and Sage does > compute this exactly. But for analytic rank >1 the "analytic Sha" is > just the value predicted by BSD which is not known theoretically to be > rational and can only be computed as a floating point approximation, > for which it is most honest to leave as such. > > John Cremona > > On 16 October 2013 10:39, Georgi Guninski <gunin...@guninski.com> wrote: > > Why E.sha().an() = 0 and E.sha().an_numerical() = 1.0 ? > > > > On 5.11 on linux and on cloud.sagemath.com: > > > > sage: E=EllipticCurve(QQ,[0, 0, 1, -79, > > 342]);E.sha().an(),E.sha().an_numerical() > > (0, 1.00000000000000) > > #^ why different and 0 is integer ? > > sage: E.sha().bound() > > (0, 0) > > > > sage: type(E.sha().an()) > > <type 'sage.rings.integer.Integer'> > > sage: E.rank(),E.analytic_rank() > > (5, 5) > > > > sage: E.conductor() > > 19047851 > > > > E.sha().an_padic(3) # stopped this at about 7G of RAM > > > > -- > > You received this message because you are subscribed to the Google Groups > > "sage-support" group. > > To unsubscribe from this group and stop receiving emails from it, send an > > email to sage-support+unsubscr...@googlegroups.com. > > To post to this group, send email to sage-support@googlegroups.com. > > Visit this group at http://groups.google.com/group/sage-support. > > For more options, visit https://groups.google.com/groups/opt_out. > > -- > You received this message because you are subscribed to the Google Groups > "sage-support" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sage-support+unsubscr...@googlegroups.com. > To post to this group, send email to sage-support@googlegroups.com. > Visit this group at http://groups.google.com/group/sage-support. > For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/groups/opt_out.
