On Saturday, May 24, 2014 9:18:29 AM UTC-7, Volker Braun wrote: > > Its a 4:1 map so you can't invert it... >
I would find that surprising. For a general plane cubic, there are good recipes for getting a 9:1 map to a Weierstrass model in general and a 1:1 map when a rational point is specified. A 4:1 map is rather unnatural to get in that situation. You'd expect that from a y^2=quartic in x model. Indeed, the map returned is invertible, the inverse being: [ -12*x*z - 4*y*z, 32*x*z, x^2 - 28*x*z - 4*y*z] -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
