Lagrangian mechanics

Summary

Lagrangian mechanics is a formulation of classical mechanics in which a system is described by one function, the Lagrangian, of its coordinates and velocities. The motions are the solutions of the Euler–Lagrange equations of this function, or equivalently the stationary points of the action. It works in any coordinates and it removes the forces of ideal constraints from the equations. It is the bridge from Newton's laws to Hamiltonian mechanics, to symmetries and conservation laws, and to field theory.