说明：  插值函数, 称为被插函数. 最小二乘拟合: 已知一批离散的数据 , 互不相同,寻求一个拟合函数 ,使 与 的误差平方和在最小二乘意义下最小.在最小二乘意义下确定的 称为最小二乘拟合函数
(Interpolation function, referred to as interpolation function. Least-squares fitting: a known number of discrete data, different from each other, to find a fitting function, so that the error sum of squares and least-squares sense at a minimum. At a minimum the sense of二乘identified as the least-squares fitting function)