2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/95194A new version of classical S-procedure in system theory is proposed based on duality in the space of positive definite matrices and introduction of matrix Lagrange multipliers. A new proof and extension of the recent results of T.Iwasaki, S. Hara, A. Fradkov ( Systems & Control Letters, 2005. Vol 54 (7), pp 681-691) concerning equivalence between frequency domain inequality on finite frequency range and constrained dissipativity property for linear systems is given. The results of this paper extend S-procedure to allow for analysis and design of systems with matrix inequalities constraints.Optimization and Control93C05(Primary) 49N10,49N15 (Secondary)text