so that the coordinates ( u 1 , u 2 ) {\displaystyle (u_{1},u_{2})} are given in terms of ( v 1 , v 2 ) {\displaystyle (v_{1},v_{2})} by ( u 1 , u 2 ) = f ( v 1 , v 2 ) {\displaystyle (u_{1},u_{2})=f(v_{1},v_{2})} . The Jacobian matrix of this transformation is given by