Letters: An unified EM algorithm for PCA and KPCA

  • Authors:
  • Haixian Wang;Zilan Hu

  • Affiliations:
  • Key Laboratory of Child Development and Learning Science of Ministry of Education, Southeast University, Nanjing, Jiangsu 210096, PR China;School of Mathematics and Physics, Anhui University of Technology, Maanshan, Anhui 243002, PR China

  • Venue:
  • Neurocomputing
  • Year:
  • 2007

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Abstract

In this note, from another point of view and in a more general situation, we formulate an EM algorithm for finding the leading eigen-system of any positive semi-definite matrix in a very simple derivation. The proposed EM approach can directly compute not only the eigen-system of sample covariance matrix in data space but also that of kernel matrix. Thus, the proposed algorithm provides an unified framework for EM-based principal component analysis (PCA) and kernel PCA (KPCA). Particularly, when it is applied to KPCA, it is a dual form of the commonly used constrained EM algorithm for performing KPCA. And thus it is a beneficial complementarity or dual description of the constrained EM method.