1. A computer-implemented method for generating a passive model of a structure, the method comprising the steps of: receiving, in memory, parameter data corresponding to the structure, the parameter data being represented as a first rectangular matrix having M rows and N columns, M being different than N; generating by a processor a second square matrix based on the first matrix, the square matrix having L rows and columns such that L is equal to the least of M and N and represents L distinct frequencies used in generating the parameter data; generating by the processor eigenvalues of the square matrix; determining by the processor a number K of significant eigenvalues; selecting by the processor K values from the first matrix; and generating by the processor a model matrix H using the K selected values, the model matrix H modeling the structure; determining by the processor a quality of fit between the model matrix H and the first matrix; and if the fit quality is less than a threshold value, (i) selecting by the processor at least one additional value from the first matrix, and (ii) generating by the processor an updated model matrix H by repeating the generating step using the K previously selected values and the at least one additional selected value.