The Nonlinear Synthesis Tools allow the user to design nonlinear control systems using a simulation model of the dynamic system as the starting point. The simulation models can be built using MATLAB or Simulink. No symbolic manipulations are required for control system synthesis. Using a GUI, the user selects a nonlinear system design method and provides the appropriate design parameters. The software delivers nonlinear controller designs in the form of an M-file or C code. This code can be coupled to the MATLAB/Simulink simulation model to assess the closed-loop performance of the dynamic system.