Approximating Subdifferentials by Random Sampling of Gradients

  • Authors:
  • J. V. Burke;A. S. Lewis;M. L. Overton

  • Affiliations:
  • -;-;-

  • Venue:
  • Mathematics of Operations Research
  • Year:
  • 2002

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Abstract

Many interesting real functions on Euclidean space are differentiable almost everywhere. All Lipschitz functions have this property, but so, for example, does the spectral abscissa of a matrix (a non-Lipschitz function). In practice, the gradient is often easy to compute. We investigate to what extent we can approximate the Clarke subdifferential of such a function at some point by calculating the convex hull of some gradients sampled at random nearby points.