Title
Convergence of the Restricted Nelder-Mead Algorithm in Two Dimensions.
Abstract
The Nelder-Mead algorithm, a longstanding direct search method for unconstrained optimization published in 1965, is designed to minimize a scalar-valued function f of n real variables using only function values, without any derivative information. Each Nelder-Mead iteration is associated with a nondegenerate simplex defined by n + 1 vertices and their function values; a typical iteration produces a new simplex by replacing the worst vertex by a new point. Despite the method's widespread use, theoretical results have been limited: for strictly convex objective functions of one variable with bounded level sets, the algorithm always converges to the minimizer; for such functions of two variables, the diameter of the simplex converges to zero but examples constructed by McKinnon show that the algorithm may converge to a nonminimizing point. This paper considers the restricted Nelder-Mead algorithm, a variant that does not allow expansion steps. In two dimensions we show that for any nondegenerate starting simplex and any twice-continuously differentiable function with positive definite Hessian and bounded level sets, the algorithm always converges to the minimizer. The proof is based on treating the method as a discrete dynamical system and relies on several techniques that are nonstandard in convergence proofs for unconstrained optimization.
Year
DOI
Venue
2012
10.1137/110830150
SIAM JOURNAL ON OPTIMIZATION
Keywords
DocType
Volume
direct search methods,nonderivative optimization,derivative-free optimization,Nelder-Mead method
Journal
22
Issue
ISSN
Citations 
2
1052-6234
5
PageRank 
References 
Authors
0.74
9
3
Name
Order
Citations
PageRank
Jeffrey C. Lagarias11049139.02
Bjorn Poonen27716.89
Margaret H. Wright31233182.31