Lagrange equations Hamilton-Jacobi equations 4 Mechanics 2 Einstein field equations 1 Hamiltonian operator 1 Lagrangian functions 1 Lagrangian points 1 Least action 1 Mechanics, Analytic 1 Numerical solutions 1 Relativistic mechanics 1 SCIENCE / Mechanics / General 1 SCIENCE / Mechanics / Solids 1 Schwarzschild black holes 1 Study and teaching 1 Variational principles 1