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CMA Research Report


MRR02-002

Z.F. Li, M.R. Osborne and T. Prvan

Numerical algorithms for constrained maximum likelihood estimation


Abstract:  This paper describes an algorithm for solving constrained maximum likelihood estimation that incorporates a number of novel features. This new algorithm is a SQP type method, we call it MLESOL. MLESOL maintains the use of an estimate of Fischer information matrix to the Hessian of the negative log-likelihood but also encompasses a secant approximation S to the second-order part of the augmented Lagrangian function along with tests for when to use this information. S is sized before updating. The local quadratic model used has a form something like that of Tapia's SQP augmented scale BFGS secant method but exploring the additional structure of the problem. The step choice algorithm is based on minimizing a local quadratic model subject to the linearized constraints and an elliptical trust region centered at the current approximate minimizer. This is accomplished using the approach of Byrd and Omojokun trust region, together with a special module for assessing the quality of the step thus computed. The numerical performance of Algorithm MLESOL is studied by means of an example involving the estimation of a mixture density.


AMS Classification:  65L10
Date:  21 January 2002

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