Estimation of Coefficients in a Rational Function from Observed Values.

A method for estimating the coefficients in a rational function representation of the frequency response function of a dynamic system is presented. A nonlinear least squares approach is used and this requires initial estimates for the coefficients. The first attempt to find initial estimates was not satisfactory, but a second approach, which can be thought of as a linear approximation to the nonlinear problem, was much more successful. Tests have been carried out with both generated and experimental data and reasonable estimates have been achieved.... Coefficients, Rational functions, Frequency response, Dynamical systems, Least squares method.