There is provided a control system for a powertrain system including an electro-mechanical transmission operative in a plurality of fixed gear modes and continuously variable modes. The control system is adapted to identify preferred operating conditions for operating the powertrain in a fixed gear operating range state. The method comprises determining a range of permissible input torques. States for input torque are iteratively selected, and a motor torque output from the first electrical machine is optimized based upon the selected state for the input torque. A motor torque output from the second electrical machine is determined based upon the optimized motor torque output from the first electrical machine. A cost for each of the iteratively selected states for the input torque and the motor torques from the first and second electrical machines is calculated. A preferred operating range is identified based upon the plurality of costs.