lagrange插值　在数值分析中，拉格朗日插值法是以法国十八世纪数学家约瑟夫·拉格朗日命名的一种多项式插值方法。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。如对实践中的某个物理量进行观测，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。(interpolation　 In numerical analysis, the Lagrange interpolation method is a polynomial interpolation method named after the French mathematician Joseph Lagrange in the eighteenth century. In many practical problems, functions are used to express certain internal relations or laws, and many functions can only be understood through experiments and observations. If a physical quantity is observed in practice and the corresponding observations are obtained in several different places, the Lagrange interpolation method can find a polynomial, which just takes the observed values at each observation point.)