Two Nonmonotone Proximal Gradient Methods for Nonsmooth Optimization over the Stiefel Manifold
摘要
We propose two nonmonotone retraction-based proximal gradient methods for solving a class of nonconvex nonsmooth optimization problems over the Stiefel manifold. The proposed methods are equipped with the descent direction obtained by a proximal mapping restricted in tangent space of the manifold and the Barzilai-Borwein stepsizes determined by two recent iteration points and the corresponding descent directions. By employing, respectively, the Grippo-Lampariello-Lucidi nonmonotone line search strategy and the Dai-Fletcher nonmonotone line search strategy, our proposed methods are proved to be globally convergent. Analysis on the iteration complexity for obtaining an ϵ-stationary solution is provided. Numerical results on the sparse principle component analysis problems demonstrate the efficiency of our methods.