Research of universal characteristic curve using MATLAB

This paper proposes two surface fitting methods, one is direct surface fitting method and the other is a method, which mixes polynomial and interpolation to get fitting curve and then generate the fitting surface. The engine universal characteristic curve can be drawn using iso-line method from the given surface. The two methods cannot only be effective, but also can deduce more accurate curve functions and intuitive fitting curves. Both of the methods are simple and have intuitive physical meaning.