An ADMM algorithm for solving a proximal bound-constrained quadratic   program
  We consider a proximal operator given by a quadratic function subject to bound constraints and give an optimization algorithm using the alternating direction method of multipliers (ADMM). The algorithm is particularly efficient to solve a collection of proximal operators that share the same quadratic form, or if the quadratic program is the relaxation of a binary quadratic problem. 
Miguel \'A. Carreira-Perpi\~n\'an
math.OC cs.LG stat.ML