ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Wed, 21 Jun 2017 17:43:25 +0200Compose Affine/Projective Curve morphism with Elliptic Curve isogenyhttps://ask.sagemath.org/question/38045/compose-affineprojective-curve-morphism-with-elliptic-curve-isogeny/When I tried to do this, I got TypeError: ... must be a map to multiply it by Isogeny ...
And when I tried to dehomogenize projective curve morphism in x,y,z by z-coordinate, the remaining variables become x0 and x1. Can I keep them as x and y instead?
EDIT: Example code:
k = GF(23)
x,y,z = k['x,y,z'].gens()
d = k(2)
C = Curve([x^3+y^3+z^3-3*d*x*y*z]) #domain curve
a = d+2
b = 4*(d^2+d+1)/3
E = EllipticCurve(y^2-x^3-(a*x+b)^2) #codomain curve
m = b
n = 4*(d^3 -1)/3
X = m*(x+y+z)
Y = n*(z-y)
Z = -z-y-d*x
f = C.Hom(E)([X,Y,Z]) #map from C to E
Q = E(2,9,1) #a point on E
g = E.isogeny(Q) #isogeny
g*f #TypeError hereRoadWed, 21 Jun 2017 17:43:25 +0200https://ask.sagemath.org/question/38045/