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For a linear non-Hermitian system, I demonstrate that a Hamiltonian can be constructed such that the non-Hermitian equations can be expressed exactly in the form of Hamilton's canonical equations. This is first shown for discrete systems…

Quantum Physics · Physics 2023-09-13 Qi Zhang

We compute the Hamiltonian and Lagrangian associated to the large deviations of the trajectory of the empirical distribution for independent Markov processes, and of the empirical measure for translation invariant interacting Markov…

Probability · Mathematics 2015-06-17 Frank Redig , Feijia Wang

A short review of basic formulas from Hamiltonian formalism in classical mechanics in the case when Lagrangian contains N time-derivatives of n coordinate variables. For non-local models N=infinity.

High Energy Physics - Theory · Physics 2008-12-25 A. Morozov

We present a unified geometric framework for describing both the Lagrangian and Hamiltonian formalisms of contact autonomous mechanical systems, which is based on the approach of the pionnering work of R. Skinner and R. Rusk. This framework…

Mathematical Physics · Physics 2020-08-13 Manuel de León , Jordi Gaset , Manuel Laínz , Xavier Rivas , Narciso Román-Roy

It is well-known that if a symplectic integrator is applied to a Hamiltonian system, then the modified equation, whose solutions interpolate the numerical solutions, is again Hamiltonian. We investigate this property from the variational…

Numerical Analysis · Mathematics 2017-11-07 Mats Vermeeren

Paper is devoted to maintaining the simple objective: We want to provide Hamiltonian canonical form for autonomous dynamical system reducible to even-dimensional one. Along the road we construct new class of conserved quantities, called…

Mathematical Physics · Physics 2020-08-28 Artur Kobus

We use a recently found method to characterise all the invertible fourth-order difference equations linear in the extremal values based on the existence of a discrete Lagrangian. We also give some result on the integrability properties of…

Mathematical Physics · Physics 2019-10-28 Giorgio Gubbiotti

The Lagrange identity expresses the second derivative of the moment of inertia of a system of material points through kinetic energy and homogeneous potential energy, from which follows the Jacobi well-known result on the instability of a…

Exactly Solvable and Integrable Systems · Physics 2026-03-31 A. V. Tsiganov

Textbook treatments of classical mechanics typically assume that the Lagrangian is nonsingular. That is, the matrix of second derivatives of the Lagrangian with respect to the velocities is invertible. This assumption insures that (i)…

Classical Physics · Physics 2023-02-28 J. David Brown

The Lagrangian-Hamiltonian unified formalism of R. Skinner and R. Rusk was originally stated for autonomous dynamical systems in classical mechanics. It has been generalized for non-autonomous first-order mechanical systems, as well as for…

Mathematical Physics · Physics 2015-12-15 Pedro D. Prieto-Martínez , Narciso Román-Roy

An interesting family of geometric integrators for Lagrangian systems can be defined using discretizations of the Hamilton's principle of critical action. This family of geometric integrators is called variational integrators. In this…

Mathematical Physics · Physics 2015-06-16 Leonardo Colombo , David Martín de Diego , Marcela Zuccalli

We have recently presented an extension of the standard variational calculus to include the presence of deformed derivatives in the Lagrangian of a system of particles and in the Lagrangian density of field-theoretic models. Classical…

Mathematical Physics · Physics 2017-06-30 J. Weberszpil , J. A. Helayël-Neto

We derive the Helmholtz theorem for Hamiltonian systems defined on time scales in the context of nonshifted calculus of variations which encompass the discrete and continuous case. Precisely, we give a theorem characterizing first order…

Optimization and Control · Mathematics 2015-07-23 Frédéric Pierret

Li\'enard-type equations are used for the description of various phenomena in physics and other fields of science. Here we find a new family of the Li\'enard-type equations which admits a non-standard autonomous Lagrangian. As a by-product…

Exactly Solvable and Integrable Systems · Physics 2016-08-18 Nikolai A. Kudryashov , Dmitry I. Sinelshchikov

It is known that a linear hamiltonian system has too many invariant measures, thus the problem of convergence to Gibbs measure has no sense. We consider linear hamiltonian systems of arbitrary finite dimension and prove that, under the…

Mathematical Physics · Physics 2013-02-21 A. A. Lykov , V. A. Malyshev

The systematization of the purely Lagrangean approach to constrained systems in the form of an algorithm involves the iterative construction of a generalized Hessian matrix W taking a rectangular form. This Hessian will exhibit as many left…

High Energy Physics - Theory · Physics 2008-11-26 Heinz J. Rothe , Klaus D. Rothe

We show that if a Lagrangian is invariant under a transformation (with the invariance defined in the standard manner), then the equations of motion obtained from it maintain their form under the transformation. We also show that the…

Classical Physics · Physics 2017-05-25 G. F. Torres del Castillo , A. Moreno-Ruiz

In this paper, the theory of smooth action-dependent Lagrangian mechanics (also known as contact Lagrangians) is extended to a non-smooth context appropriate for collision problems. In particular, we develop a Herglotz variational principle…

Optimization and Control · Mathematics 2024-07-01 Asier López-Gordón , Leonardo Colombo , Manuel de León

Action-dependent field theories are systems where the Lagrangian or Hamiltonian depends on new variables that encode the action. They model a larger class of field theories, including non-conservative behavior, while maintaining a…

High Energy Physics - Theory · Physics 2025-05-01 Manuel de León , Jordi Gaset Rifà , Miguel C. Muñoz-Lecanda , Xavier Rivas , Narciso Román-Roy

By one of the most fundamental principles in physics, a dynamical system will exhibit those motions which extremise an action functional. This leads to the formation of the Euler-Lagrange equations, which serve as a model of how the system…

Machine Learning · Computer Science 2025-03-11 Yana Lishkova , Paul Scherer , Steffen Ridderbusch , Mateja Jamnik , Pietro Liò , Sina Ober-Blöbaum , Christian Offen