Abstract: A method for deriving a piecewise-linear model which comprises measuring the behavior of a desired characteristic of an object. Recording the observations in a computer memory. Creating a piece-wise linear model of the observations based on the highest and lowest valued observations. Computing an error value for the dependent variable of each observation based on the piece-wise linear model. Determining a new piece-wise linear model based on two segments by interpolation. Recursively repeating the steps of computing error values and determining an improved piece-wise linear model until a predetermined acceptance condition is achieved. Performing a computer simulation of the desired characteristic of the object using the improved piecewise-linear model.