1. An adaptive controller for a nonlinear system, the controller comprising: a non-linear signal processing circuit; a circuit based on a Volterra series, coupled to receive input sample values and provide output signals as an input terminal of the non-linear signal processing circuit, the circuit based on the Volterra series having a transfer function defined by a predetermined number, P, of coefficients; an alignment and compensation circuit, coupled to the input terminal and to an output terminal of the nonlinear signal processing circuit, the alignment and compensation circuit being arranged to align the input samples and output samples of the nonlinear signal processing circuit; and a processor, configured to: generate a P×P matrix using samples from the nonlinear signal processing circuit; normalize elements in the P×P matrix using respective normalization factors; solve a system of P linear equations based on the P×P matrix to obtain P values; multiply ones of the P values by inverses of respective ones of the normalization factors to generate the P coefficients; and apply the P coefficients to the circuitry based on the Volterra series to compensate signals processed by the nonlinear signal processing circuit.