（拟合）
用给定的多项式，y=x3-6x2+5x-3，产生一组数据(xi,yi，i=1,2,…,n),再在yi上添加随机干扰(可用rand产生(0,1)均匀分布随机数,或用rands产生N(0,1)分布随机数)，然后用xi和添加了随机干扰的yi作的3次多项式拟合，与原系数比较。
如果作2或4次多项式拟合，结果如何？
,(Fitting) with a given polynomial, y = x3-6x2+5 x-3, generated a set of data (xi, yi, i = 1,2, ..., n), then add a random disturbance yi ( can be generated rand (0,1) uniformly distributed random number, or rands generated N (0,1) distribution of random numbers), and then added with xi and yi for random interference of the 3 times polynomial fitting, and the original coefficient. If 2 or 4 times for polynomial fitting, the result?