说明：  用matlab编写的函数式文件：function r=ksrlin(x,y,h,N).用于进行局部线性拟合，x、y为自、因变量，h为核估计的带宽，N为数据点的个数。
(Using matlab functional file: function r = ksrlin (x, y, h, N). Used for local linear fitting, x, y as independent, dependent variable, h is the kernel estimator of bandwidth, N is the data the number of points.)