根据离散点进行二次的拉格朗日插值， 解决了等时间距获取值的问题, 但这是二次插值, 也就是拟合的是二次及二次方程以下的函数- According to discrete points for the two Lagrange interpolation, solving the problem of equal time interval, but this is the two interpolation, that is, the two and two times the equation