Hi Yongwei,
You would need to mathematically approximate the original transfer function and express it in terms of polynomials with integer powers, which can be handled by MATLAB and Simulink.
In addition, there are two references on MATLAB Central that allow you to approximate transfer functions where the power of 's' might not be an integer:
However, please note that MATLAB File Exchange is a forum for our product users to interact, exchange information and knowledge without MathWorks involvement. Feel free to contact the author of this submission directly for specific questions about the implementation
