拉格朗日插值法可以找到一个多项式，其恰好在各个观测的点取到观测到的值。数学上来说，拉格朗日插值法可以给出一个恰好穿过二维平面上若干个已知点的多项式函数。(The Lagrange interpolation method can find a polynomial that happens to be taken to the observed value at the point of each observation. Mathematically, the Lagrange interpo