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Gradient Based Methods: Functional vs Parametric Forms

Authors:Dodd Tony, The University of Sheffield, United Kingdom
Nair Sumitra, The University of Sheffield, United Kingdom
Harrison Robert F., The University of Sheffield, United Kingdom
Topic:1.1 Modelling, Identification & Signal Processing
Session:Nonlinear System Identification - Kernel Methods
Keywords: reproducing kernel, Hilbert spaces, system identification, function approximation, Gaussian processes, iterative methods, least-squares approximation, regularisation

Abstract

Reproducing kernel Hilbert spaces (RKHS) provide a unified framework for the solution of a number of function approximation and signal estimation problems. A significant problem with RKHS methods for real applications is the poor scaling properties of the algorithms with the number of data. It is therefore often necessary to use iterative algorithms. Steepest descent and conjugate gradient solutions for approximation in RKHS are presented in this paper. Four different approaches are described and compared on a benchmark system identification problem.