分段线性插值法的思想精髓是， 把曲线看作若干段首尾相连的直线 段；根据每段直线的斜率来求算该线段所在区段内的数据值。相邻两 个线段的接点称为标定点。由下图可知，当标定点选择合理时，计算 结果可以非常接近实际值。 -The spirit and essence of the piece-wise linear interpolation curve as several segments of the end-to-end straight-line segment calc