许多实际问题中都用函数来表示某种内在联系或规律，而不少函数都只能通过实验和观测来了解。在若干个不同的地方得到相应的观测值，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。(In many practical problems, functions are used to express certain internal relations or laws, and many functions can only be understood by experiments and observations. The corresponding observations are obtained in several different places, and the Lagrange interpolation method can find a polynomial which takes the observed values exactly at each observation point.)