Fast Primal-Dual Gradient Method for Strongly Convex Minimization Problems with Linear Constraints

In this paper, we consider a class of optimization problems with a strongly convex objective function and the feasible set given by an intersection of a simple convex set with a set given by a number of linear equality and inequality constraints. Quite a number of optimization problems in applications can be stated in this form, examples being entropy-linear programming, ridge regression, elastic net, regularized optimal transport, etc. We extend the Fast Gradient Method applied to the dual problem in order to make it primal-dual, so that it allows not only to solve the dual problem, but also to construct nearly optimal and nearly feasible solution of the primal problem. We also prove a theorem about the convergence rate for the proposed algorithm in terms of the objective function residual and the linear constraints infeasibility.