x2, y2, x1, y1, 
2*x1^2-x1*y1-2*x2^2+x2*y2+4
4*x1*x2-x1*y2-x2*y1
x1*y1-x2*y2-2*y1^2+2*y2^2+4
x1*y2+x2*y1-4*y1*y2
