对 -方法导出的几种隐式差分格式编程实现求出数值解；估计数值解的误差界；大致比较几种不同格式的优劣；结合格式的相容性、稳定性和收敛性条件简单分析计算结果-- Export several implicit difference scheme for programming to find the numerical solution estimated error bounds for the numerical solution rough comparison of the pros a