On the symmetries of the modified Emden-type equation

Abstract

For an autonomous system the symmetries of the Lagrangian are embedded in the symmetries of the differential equation. Recently, it has been found that the modified Emden-type equations follow from non-standard Lagrangian functions which involve neither the kinetic energy term nor the potential function. By working with one such Lagrangian we have calculated the Lagrangian symmetries and explicitly demonstrated that, as in the case of standard Lagrangian functions, the variational symmetries of the non-standard Lagrangian are also included in the Lie symmetries of the differential equation.