Index: sage/schemes/elliptic_curves/ell_generic.py
===================================================================
--- sage/schemes/elliptic_curves/ell_generic.py	(revision 6528)
+++ sage/schemes/elliptic_curves/ell_generic.py	(revision 6777)
@@ -777,4 +777,34 @@
         return constructor.EllipticCurve(self.base_ring(), ap)
 
+    def rst_transform(self, r, s, t):
+        """
+        Transforms the elliptic curve using the unimodular (u=1) transform with standard parameters [r,s,t].
+        
+        Returns the transformed curve.
+        """
+        ##Ported from John Cremona's code implementing Tate's algorithm.
+        (a1, a2, a3, a4, a6) = self.a_invariants()
+        a6 += r*(a4 + r*(a2 + r)) - t*(a3 + r*a1 + t)
+        a4 += -s*a3 + 2*r*a2 - (t + r*s)*a1 + 3*r*r - 2*s*t
+        a3 += r*a1 + 2*t
+        a2 += -s*a1 + 3*r - s*s
+        a1 += 2*s
+        return constructor.EllipticCurve([a1, a2, a3, a4, a6])
+    
+    def scale_curve(self, u):
+        """
+        Transforms the elliptic curve using scale factor u, i.e. multiplies c_i by u^i.
+        
+        Returns the transformed curve.
+        """
+        ##Ported from John Cremona's code implementing Tate's algorithm.
+        (a1,a2,a3,a4,a6) = self.a_invariants()
+        a1 *= u
+        a2 *= u^2
+        a3 *= u^3
+        a4 *= u^4
+        a6 *= u^6
+        return constructor.EllipticCurve([a1, a2, a3, a4, a6])
+
     def discriminant(self):
         """