
It is known that an \(n\times n\) structured matrix \(M\) can be associated with an appropriate displacement operator \(L\) such that the rank \(r\) of \(L(M)\) satisfies \(r\ll n\) and the \(n^2\) entries of \(L(M)\) can be represented via only \(2rn\) parameters. The authors present a general method to express \(M\) via \(L(M)\) under very mild nonsingularity assumptions. The method unifies the derivation of known formulae and gives new formulae, in particular for the tangential Nevalinna-Pick problems. It accelerates known solution algorithms. The authors obtain general new matrix representations in the confluent case and substantially improve the known estimates for the norm \(\| L^{-1}\| \) which is critical in computations based on the displacement approach.
tangential confluent Nevanlinna-Pick problem, Applications of operator theory in numerical analysis, Analysis of algorithms and problem complexity, displacement rank, Toeplitz operators, Hankel operators, Wiener-Hopf operators, structured matrices, Direct numerical methods for linear systems and matrix inversion, Linear operator methods in interpolation, moment and extension problems, inverse displacement operators
tangential confluent Nevanlinna-Pick problem, Applications of operator theory in numerical analysis, Analysis of algorithms and problem complexity, displacement rank, Toeplitz operators, Hankel operators, Wiener-Hopf operators, structured matrices, Direct numerical methods for linear systems and matrix inversion, Linear operator methods in interpolation, moment and extension problems, inverse displacement operators
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