“…As it was shown there, when the objective function does not have an analytical expression (as in the present study), application of minimization techniques like a gradient search (Jacobs, 1977) is impossible. In this case, methods of direct search are usually used if Ext is a singleextremum function; otherwise, methods of global optimization are applied (Rosenbrock, 1960;Powell, 1964;Nelder & Mead, 1965;Solomatine et al, 1999;Duan, 2003). Many of them are based on the statistical methods of finding the extremum of Ext (vector of optimized parameters) (Rastrigin, 1968;Gupta et al, 1998;Solomatine et al, 1999).…”