I have added a trac ticket (#740) for this, which I intend to do over the next couple of days:
Implement standard transformations for elliptic curves & points similar to pari's ellchangecurve()/ellchangepoint() with the following functionality, to apply to class EllipticCurve?_generic and class EllipticCurvePoint?(). Functionality: (1) basic operations on transformations coded as [u,r,s,t] with u!=0, including composition and inversion (since they form a group) (2) apply transform to a curve to get a new curve (3) apply transform to a point to get a new point (since points belong to curves this would create the transformed curve too, which seems a waste) (4) given two curves, test whether they are isomorphic and return either "false" or "true, [u,r,s,t]", probably only in characteristic>3 at first. This should be very easy (and in fact is contained in the functionality provided by /extcode/pari/cremona/ell_utils.gp but the intention is to do it in python as a simple thing for me to practice on before I try to do something more substantial. -- John Cremona --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
