Averaging complex subspaces via a Karcher mean approach

  • Authors:
  • K. HüPer;M. Kleinsteuber;H. Shen

  • Affiliations:
  • Department of Mathematics, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany;Department of Electrical Engineering and Information Technology, Technische Universität München, 80333 Munich, Germany;Department of Electrical Engineering and Information Technology, Technische Universität München, 80333 Munich, Germany

  • Venue:
  • Signal Processing
  • Year:
  • 2013

Quantified Score

Hi-index 0.08

Visualization

Abstract

We propose a conjugate gradient type optimization technique for the computation of the Karcher mean on the set of complex linear subspaces of fixed dimension, modeled by the so-called Grassmannian. The identification of the Grassmannian with Hermitian projection matrices allows an accessible introduction of the geometric concepts required for an intrinsic conjugate gradient method. In particular, proper definitions of geodesics, parallel transport, and the Riemannian gradient of the Karcher mean function are presented. We provide an efficient step-size selection for the special case of one dimensional complex subspaces and illustrate how the method can be employed for blind identification via numerical experiments.