Main function to execute gbest GC PSO algorithm.

def main(dimension, iterations):
    """ Main function to execute gbest GC PSO algorithm.
    """
    objective_function = minimize(functions.sphere)
    stopping_condition = max_iterations(iterations)
    (solution, metrics) = optimize(objective_function=objective_function,
                                   domain=Domain(-5.12, 5.12, dimension),
                                   stopping_condition=stopping_condition,
                                   parameters={'seed': 3758117674,
                                               'rho': 1.0, 'e_s': 15, 'e_f': 5},
                                   velocity_update=gc_velocity_update,
                                   parameter_update=update_rho,
                                   measurements=[fitness_measurement])
    return solution