Abstract: A multi-parameter control circuit supplies a number of control signals to a multiple-input system, and these regulate process parameters. A cost function, which depends on all of the parameters, is measured, and a time derivative signal is produced which represents the time differential of the cost function. There are a number of control signal circuits responsive to the cost function derivative which each include a multiplier that receives the time derivative signal, and a second input. An integrator integrates the output of the multiplier and provides a time integral to one input of an adder, a second input of which is provided with a rapidly varying incoherent signal, which can be white noise. The adder produces a parameter control output signal which is used to control the process parameter. A differentiator has an input connected to the adder output and an output that provides a time derivative of the parameter control signal to the second input of the multiplier.