scholarly journals Formal Integrability for the Nonautonomous Case of the Inverse Problem of the Calculus of Variations

Author(s):  
Oana Constantinescu
2018 ◽  
Vol 51 (18) ◽  
pp. 185202 ◽  
Author(s):  
María Barbero-Liñán ◽  
Marta Farré Puiggalí ◽  
Sebastián Ferraro ◽  
David Martín de Diego

1994 ◽  
Vol 10 (2) ◽  
pp. 245-260 ◽  
Author(s):  
M Crampin ◽  
W Sarlet ◽  
E Martinez ◽  
G B Byrnes ◽  
G E Prince

Author(s):  
M. C. Nucci ◽  
A. M. Arthurs

Fels’ conditions (Fels, M. E. 1996 Trans. Amer. Math. Soc. 348 , 5007–5029. ( doi:10.1090/S0002-9947-96-01720-5 )) ensure the existence and uniqueness of the Lagrangian in the case of a fourth-order equation. We show that when Fels’ conditions are satisfied, the Lagrangian can be derived from the Jacobi last multiplier, as in the case of a second-order equation. Indeed, we prove that if a Lagrangian exists for an equation of any even order, then it can be derived from the Jacobi last multiplier. Two equations from a Number Theory paper by Hall (Hall, R. R. 2002 J. Number Theory 93 , 235–245. ( doi:10.1006/jnth.2001.2719 )), one of the second and one of the fourth order, will be used to exemplify the method. The known link between Jacobi last multiplier and Lie symmetries is also exploited. Finally, the Lagrangians of two fourth-order equations drawn from Physics are determined with the same method.


2017 ◽  
Vol 2 (3) ◽  
Author(s):  
Veronika Chrastinová ◽  
◽  
Václav Tryhuk ◽  

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