fit

代码说明：

  Matlab中提供了一种快速实现多项式拟合的方法函数polyfit()函数， 其格式：p=polyfit(x,y,n)其中x，y为样本向量，n为拟合的多项式的项数。下面拟f(x)=sinx+x,在区间【-3,3】上以0.5为间隔进行拟合。(Matlab provides a fast way to achieve polynomial fitting function polyfit () function, The format: p = polyfit (x, y, n) where x, y as the sample vector, n is the number of items of polynomial fitting. The following proposed f (x) = sinx+ x, the interval-3,3】 【intervals on the order of 0.5 to fit.)