说明：  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 calculating under each section of the slope of the line the data values 椠渀 the segment where the segment. The contact between two adjacent segments known as calibration points. The following figure shows the reasonable choice of calibration points, the results can be very close to the actual value.)