Abstract: An apparatus (20) to control a high intensity discharge lamp (24) by generating fuzzy logic transfer functions (360, 362) with a software package (368). The fuzzy logic transfer functions (360, 362) are applied by a controller (210) for controlling the operation of the lamp (24). The first fuzzy logic transfer function (360) includes both of a lamp ignition membership function and a lamp steady state membership function. The second fuzzy logic transfer function (362) includes a first current error magnitude membership function and a second different current error magnitude membership function. Both of the first and second membership functions functionally related to both of the error current value and a PWM count change value. A current sense resistor (256) provides a signal indicative of lamp current to the controller (210). An internal real time clock (RTC) in the controller (210) measures the amount of time that the lamp (24) is operating and provides a real time signal for use in the controller (210).