1. A computer implemented method of determining parameter values of a circuit model, comprising the steps of: (a) initializing a plurality of processors with initial estimates of the parameter values of the circuit model; (b) evaluating initial estimates within a plurality of processors respectively to determine a plurality of solutions; (c) selecting a best estimate of the parameter values of the circuit model from said plurality of solutions; (d) setting at least one of said plurality of processors having said best estimate to run in gradient mode while setting others of said plurality of processors to run in random mode; and (e) evaluating estimates of the parameter values of the circuit model from said plurality of processors running in random mode until said at least one of said plurality of processors running in gradient mode determines a local minimum.