Comment on "Standard and non-standard Lagrangians for dissipative dynamical systems with variable coefficientes"

Abstract

Z.E. Musielak has reported in 2008 J. Phys. A: Math. Theor. {\bf 41} 055205 methods to obtain standard and non-standard Lagrangians and identify classes of equations of motion that admit a Lagrangian description. In this comment we show how to obtain new non-standard Lagrangians using the non-standard Lagrangians previously found. In particular, it is demonstrated that for every non-standard Lagrangian one can generate a new non-standard Lagrangian associated to a new equation of motion.