拉格朗日插值法，给定n个点，求n-1次插值函数以及插值结果。文件包含拉格朗日插值函数文件和一个例程，可以快速学习拉格朗日插值的算法。(Lagrange interpolation method. Given n points, and can get n-1 th order interpolation function and interpolation results. The file contains Lagrange interpolation function file and an exercise example, you can quickly learn Lagrange interpolation algorithm.)