说明：  本代码为牛顿下山法求解非线性方程组。其调用格式为[r,m]=mulDNewton(F,x0,eps) 其中F:非线性方程组，x0：初始解，eps：解的精度；r：求得的一组解，n：迭代步数。
(The code for Newton' s method for solving nonlinear equations. Its call format [r, m] = mulDNewton (F, x0, eps) where F: non-linear equations, x0: initial solution, eps: solution accuracy r: obtain a set of solution, n : the number of iterative steps.)