Gaetano Zanghirati

New Adaptive Stepsize Selections in Gradient Methods

  • G. Frassoldati
  • Luca Zanni
  • Gaetano Zanghirati
    • Categories Unconstrained Optimization Tags , , ,

    This paper deals with gradient methods for minimizing n-dimensional strictly convex quadratic functions. Two new adaptive stepsize selection rules are presented and some key properties are proved. Practical insights on the effectiveness of the proposed techniques are given by a numerical comparison with the Barzilai-Borwein (BB) method, the cyclic/adaptive BB methods and two recent monotone … Read more

    Gradient Projection Methods for Quadratic Programs and Applications in Training Support Vector Machines

  • Thomas Serafini
  • Luca Zanni
  • Gaetano Zanghirati
    • Categories Data-Mining, Quadratic Programming Tags , , , ,

    Gradient projection methods based on the Barzilai-Borwein spectral steplength choices are considered for quadratic programming problems with simple constraints. Well known nonmonotone spectral projected gradient methods and variable projection methods are discussed. For both approaches the behavior of different combinations of the two spectral steplengths is investigated. A nw adaptive stplength alternating rule is proposed, … Read more