说明：  拟牛顿法(Quasi-Newton Methods)是求解非线性优化问题最有效的方法之一。其实DFP算法、BFGS算法都属于拟牛顿法，即，DFP、BFGS都分别是一种拟牛顿法
(Quasi-Newton method (Quasi-Newton Methods) is one of the most effective methods for solving nonlinear optimization problems. In fact, the DFP algorithm, BFGS algorithm belongs to the quasi-Newton method, ie, DFP, BFGS are a quasi-Newton method)