Editing Variational principle (section)

==Examples==
===In mathematics===
* [[Ekeland's variational principle]] in mathematical optimization
* The [[finite element method]]
* The variation principle relating [[topological entropy]] and [[Kolmogorov-Sinai entropy]].
===In physics===
* The [[Rayleigh–Ritz method]] for solving [[Boundary value problem|boundary-value problem]]s in elasticity and wave propagation
* [[Fermat's principle]] in [[geometrical optics]]
* [[Hamilton's principle]] in [[classical mechanics]]
* [[Maupertuis' principle]] in [[classical mechanics]]
* The [[principle of least action]] in [[mechanics]], [[electromagnetic theory]], and [[quantum mechanics]]
* The [[variational method (quantum mechanics)|variational method]] in quantum mechanics
* [[Hellmann–Feynman theorem]]
* [[Gauss's principle of least constraint]] and [[Gauss's principle of least constraint#Hertz's principle of least curvature|Hertz's principle of least curvature]]
* [[Einstein–Hilbert action|Hilbert's action principle]] in general relativity, leading to the [[Einstein field equations]].
* [[Palatini variation]]
* [[Hartree–Fock method]]
* [[Density functional theory]]
* [[Gibbons–Hawking–York boundary term]]
* [[Variational quantum eigensolver]]