A method for analyzing IC system performance. The method includes receiving system variables that correspond to an IC system; normalizing the system variables; using an infinite dimensional Hilbert space, modeling a system response as a series of series of orthogonal polynomials; and, solving for coefficients of the series of orthogonal polynomials. A system equation or a simulated response may be used to solve for the coefficients. If a simulated response is used, the coefficients may be solved by using the statistical expectance of the product of the simulated system response and the series of orthogonal polynomials. Alternatively, a simulated system response may be used to generate coefficients by performing a least mean square fit.