已知f(xn)=yn ,n=0,1,2,…,N；求通过这N+1个节点{（xn，yn）| n=0,1,2,…,N }的插值函数Pn (x)。 设计出具体的程序，分别使用拉格朗日插值，牛顿插值和三次自然样条三种算法绘制出相应的插值曲线。用三条不同颜色的曲线来表示三种插值方法在一段区间内的插值函数。要求动态显示曲线绘制全过程。-Known f (xn) = yn, n = 0,1,2, ..., N　seeking the passage of the N+ 1 nodes ((xn, yn) | n = 0,1,2, ..., N) of the intercalation value function Pn (x). Design a specific procedure, namely the use of Lagrange interpolation, Newton interpolation and three natural three-spline algorithm to map out the corresponding interpolation curve. Using three different colors to indicate the three curve interpolation methods over a period of range of interpolation function. Requirements of dynamic display curve drawing the whole process.