On the rotational invariant $L_1$-norm PCA

Sebastian Neumayer, Max Nimmer, Simon Setzer, Gabriele Steidl

Published 2019-02-11Version 1

Principal component analysis (PCA) is a powerful tool for dimensionality reduction. Unfortunately, it is sensitive to outliers, so that various robust PCA variants were proposed in the literature. Among them the so-called rotational invariant $L_1$-norm PCA is rather popular. In this paper, we reinterpret this robust method as conditional gradient algorithm and show moreover that it coincides with a gradient descent algorithm on Grassmannian manifolds. Based on this point of view, we prove for the first time convergence of the whole series of iterates to a critical point using the Kurdyka-{\L}ojasiewicz property of the energy functional.