在最优化问题中，运用拉格朗日松弛时为了解决其对偶问题，可以使用次梯度方法进行求解拉格朗日乘子。(Lagrangean relaxation, a technique of quite general applicability, is studied in the particular context of the optimization problem with arbitrary additional constraints. To solve the Lagrangian dual, w

用次梯度方法求解拉格朗日对偶问题的例子。。。。。。(Solve the optimal problem)