数值微分精度及步长的关系，截断误差和舍入误差，体会误差对结果的影响，用算法1 和算法2 分别得到的结果进行比较，由Taylor公式可得到两种算法的截断误差-Accuracy of numerical differentiation and the relationship between step length, truncation error and rounding error, the error on the results of experience with algorithm 1