A regularity result for the singular values of a transfer matrix and a quadratically convergent algorithm for computing its L_infinity-norm

A regularity result for the singular values of a transfer matrix and a quadratically convergent algorithm for computing its L_infinity-norm

S. Boyd and V. Balakrishnan

Systems & Control Letters, 15:1-7, 1990


Abstract: The ith singular value of a transfer matrix need not be a differentiable function of frequency where its multiplicity is greater than one. We show that near a local maximum, however, the largest singular value has a Lipschitz second derivative, but need not have a third derivative. Using this regularity result, we give a quadratically convergent algorithm for computing the L_infinity-norm of a transfer matrix.

Keywords: Multi-input multi-output linear system, transfer matrix, singular values, regularity of singular values, L_infinity-norm, computation of L_infinity-norm, quadratic convergence, H_infinity control.


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