A method and apparatus for determining a preferred operating range for a plurality of torque-generative devices is provided. Each device is operable to provide motive torque to a transmission. The invention includes defining a first and a second operating range in a first operating space. The first operating range and the second operating range are mathematically transformed to a second operating space. The preferred operating range is defined in the second operating space based upon the transformed first operating range and the transformed second operating range. The first operating range is defined based upon torque output for each of the torque-generative devices. The second operating range is defined based upon output of an electrical energy storage device operable to provide electrical energy to each of the torque-generative devices.