“…The Lagrangian of a DE is not unique and certain DEs, like scalar-evolution equations, do not admit Lagrangians [5,8]. There are several techniques developed to construct Lagrangians for special classes of ODEs, PDEs and their systems by various authors [4,5,7,8,9,15]. The question of finding a Lagrangian is an open problem as most of the approaches apply to some special classes of DEs (both ODEs and PDEs) and their systems.…”