On conditions for optimality in least pth approximation withp → ∞

This paper presents a theoretical discussion of the necessary and sufficient conditions for optimality in generalized nonlinear leastpth approximation problems forp → ∞. In the limit, the conditions for a minimax approximation are derived, as is to be expected. Numerical examples involving the modeling of a linear time-invariant fourth-order system by a second-order model and the design of quarter-wave transmission-line transformers illustrate the results.