*3.1. Analysis of Truncation Error*

In this section, the truncation errors of the second derivative calculated by these schemes are compared. The results are shown in Table 1. *α*, *β*, *a*, *b*, *c* are the difference coefficient matrices. It can be seen from Table 1 that, although the three methods can achieve a certain order of spatial accuracy, the truncation error is relatively different. The truncation error of the traditional difference scheme (central difference scheme) in calculating the second-order partial derivative is greater than that of the CCD and CSCD.


**Table 1.** Truncation errors in various difference schemes for the second-order derivative calculations.
