Hi, I am trying to using " VariationalMethods " packge to get the EulerEquations in Cylindrical coordinates system. But I can not get the right results (In Cartesian coordinates, it generates Laplacian equation. Obviously, the result in Cylindrical coordinates is wrong ). Please point out my mistake ! Thank you very much ! ![enter image description here](/c/portal/getImageAttachment?filename=QQ%E5%9B%BE%E7%89%8720140924191520.png&userId=353964)