conjugate gradients; Barzilai-Borwein steplength; contact mechanics
We propose a modification of MPGP algorithm for solving minimizing problem
of strictly convex quadratic function subject to separable spherical constraints. This active set based algorithm explores the faces by the conjugate gradients and changes the active sets and active variables by the gradient projection with the Barzilai-Borwein steplength. We show how to use the algorithm for the solution of separable and equality constraints. The power of our modification is demonstrated on the solution of a contact problem with Tresca friction.