Approximate H∞ identification using partial sum operators in a disc algebra basis

H_∞ system identification using a basis in the disc algebra is presented. The approximate model is represented by a partial sum with respect to this basis. The identification problem is to estimate the expansion coefficients of this partial sum. Since the constructed basis functions cannot be represented analytically, they are approximated in order to arrive at a model in a suitable form. An algorithm is presented which calculates the model parameters from the frequency domain data set