Given a system of linear equations and inequalities in n variables, a famous result due to A.J. Hoffman says that the distance of any point in Rn to the solution set of this system is bounded above by the product of a positive constant and the absolute residual. The authors shall discuss explicit representations of this constant in dependence upon the pair of norms used for the estimation. A method for computing a special form of Hoffman constants is proposed. Finally, the authors use these results in the analysis of Lipschitz continuity for solutions of parametric quadratic programs.
