Eikonal approximation, a method of approximation useful in wave scattering equations.
Orders of approximation | Stirling's approximation | Polynomial-time approximation scheme | Born approximation | Wien approximation | Simultaneous perturbation stochastic approximation | polynomial-time approximation scheme | Korringa–Kohn–Rostoker approximation | Eikonal equation | Eikonal approximation | Diophantine approximation | Derjaguin approximation | Boussinesq approximation | Approximation |