Only center and neighboring points are used in present scheme , so the method of forward elimination and backward substitution can be directly used to solve linear simultaneous equations obtained from the scheme 該方法僅涉及中心點及相鄰網(wǎng)格點,具有四階精度,并且由所提格式得到的線性方程組是三對角線型的,可以直接采用追趕法進行求解。