The method use the a modified version Nagell's algorithm which works in any characteristic.
Reference: Tibouchi, M. ''A Nagell Algorithm in Any Characteristic'', Cryptography and Security: From Theory to Applications, 474--479, 2012.
i1 : toWeierstrass({-1,0,+1,0,0,+1,0,-1,0,+2},{1,2,1},ZZ/13) The point is not on the curve |
The object toWeierstrass is a method function.