Lagrangian may refer to:

• Lagrangian function, used to solve constrained minimization problems in optimization theory; see Lagrange multiplier
  • Lagrangian relaxation, the method of approximating a difficult constrained problem with an easier problem having an enlarged feasible set
  • Lagrangian dual problem, the problem of maximizing the value of the Lagrangian function, in terms of the Lagrange-multiplier variable; See Dual problem
• Lagrangian, a functional whose extrema are to be determined in the calculus of variations
• Lagrangian submanifold, a class of submanifolds in symplectic geometry
• Lagrangian system, a pair consisting of a smooth fiber bundle and a Lagrangian density

• Lagrangian mechanics, a formulation of classical mechanics
• Lagrangian (field theory), a formalism in classical field theory
• Lagrangian point, a position in an orbital configuration of two large bodies
• Lagrangian coordinates, a way of describing the motions of particles of a solid or fluid in continuum mechanics
• Lagrangian coherent structure, distinguished surfaces of trajectories in a dynamical system

• Joseph-Louis Lagrange (1736–1813), Italian mathematician and astronomer
• Lagrange (disambiguation)
• List of things named after Joseph-Louis Lagrange