Abstract: A method determines a global optimum of a system defined by a plurality of nonlinear equations. The method includes applying a heuristic methodology to cluster a plurality of particles into at least one group for the plurality of nonlinear equations. The method also includes selecting a center point and a plurality of top points from the particles in each group and applying a local method starting from the center point and top points for each group to find a local optimum for each group in a tier-by-tier manner. The method further includes applying a TRUST-TECH methodology to each local optimum to find a set of tier-1 optima and identifying a best solution among the local optima and the tier-1 optima as the global optimum. In some embodiments, the heuristic methodology is a particle swarm optimization methodology.