Lagrange multiplier methods are standard fare in elementary calculus courses, and they play a central role in economic applications of calculus because they often turn out to have interpretations as prices or shadow prices. You have seen them generalized to cover dynamic, non-stochastic models as Hamiltonian methods, or as byproducts of using Pontryagin’s maximum principle. In static models Lag...

Lagrange multiplier methods are standard fare in elementary calculus courses, and they play a central role in economic applications of calculus because they often turn out to have interpretations as prices or shadow prices. You have seen them generalized to cover dynamic, non-stochastic models as Hamiltonian methods, or as byproducts of using Pontryagin’s maximum principle. In static models Lag...

We present a Lagrangian method for simulating incompressible gases in 3 dimensions. Using the vorticity equation with Lagrangian particles, we create, modify and delete vortices of varying size in a manner that handles buoyancy, boundaries, viscosity and collision with deformable objects using monopoles. Our method scales linearly for parallel processing and provides user controls at varying re...

A direct approach is proposed for constructing conservation laws of discrete evolution equations, regardless of the existence of a Lagrangian. The approach utilizes pairs of symmetries and adjoint symmetries, in which adjoint symmetries make up for the disadvantage of non-Lagrangian structures in presenting a correspondence between symmetries and conservation laws. Applications are made for the...

Acceleration-induced nonlocality and the corresponding Lorentz-invariant nonlocal field equations of accelerated systems in Minkowski spacetime are discussed. Under physically reasonable conditions, the nonlocal equation of motion of the field can be derived from a varia-tional principle of stationary action involving a nonlocal Lagrangian that is simply obtained by composing the local inertial...

We study Hamiltonian stationary Lagrangian surfaces in C, i.e. Lagrangian surfaces in C which are stationary points of the area functional under smooth Hamiltonian variations. Using loop groups, we propose a formulation of the equation as a completely integrable system. We construct a Weierstrass type representation and produce all tori through either the integrable systems machinery or more di...

This paper investigates a class of Lagrangian control systems with n degrees-offreedom (DOF) and n − 1 actuators, assuming that n − 1 virtual holonomic constraints have been enforced via feedback, and a basic regularity condition holds. The reduced dynamics of such systems are described by a second-order unforced differential equation. We present necessary and sufficient conditions under which ...

In this note we consider an autonomous Tonelli Lagrangian L on a closed manifold M , that is, a C2 function L : TM −→ R such that L is fiberwise strictly convex and superlinear. Then the Euler-Lagrange equation associated with L defines a complete flow φt on TM . Define Minv to be the set of Φt-invariant, compactly supported, Borel probability measures on TM . Mather showed that the function (c...

We study the Born-Infeld equation from a Lagrangian point of view emphasizing the duality symmetry present in such systems. We obtain the Hamiltonian formulation directly from the Lagrangian. We also show that this system admits a dispersionless nonstandard Lax representation which directly leads to all the conserved charges (including the ones not previously obtained). We also present the gene...

1550-7998=20 Lagrangian perturbation theory for cosmological fluid describes structure formation in the quasinonlinear stage well. In a previous paper, we presented a third-order perturbative equation for Lagrangian perturbation with pressure. There we considered only the longitudinal modes for the first-order perturbation. In this paper, we generalize the perturbation, i.e., we consider both t...