FDM-any-accuracy

代码说明：

  电磁波、声波或地震波等数值模拟中常常会用到有限差分法，但是很多文章都只是泛泛而谈时间2阶，空间4阶等等如何用公式，本文给出了任意阶精度的泰勒展开与迭代公式。(Numerical simulation of electromagnetic, acoustic or seismic waves will often use the finite difference method, but many articles are just generalities time two bands, space, etc. How to order 4 formula, this paper presents the accuracy of any order Taylor expansion and iterative formula.)