| According to the characters of discrete variable,the concept of direction-difference-quo-tient is advanced,and a direction-difference-quotient method is developed in this paper. The method,starting from the minimum point of objective function out of feasible set and ad-vancing along the direction of minimum increasement of objective function and maximum de-creasement of constrained functions, can be used to solve a kind of optimum design problems with monotone objective function and constrained functions.The method has been applied to the optimum design of discrete variable structure. |