A Factorization of the S-Matrix into Jost Matrices
  An effective algebraic approach to $S$--matrix factorization into Jost matrices is developed in the case of coupled channels. The Jost matrix is given as a solution of boundary value Riemann -- Hilbert problem. A rational form is assumed for tangent of mixing angle, while there is no limitations for approximation of phase shifts. 
A.F.Krutov (Samara State University), D.I.Muravyev and V.E.Troitsky   (Institute of Nuclear Physics, Moscow State University)