定点数实现浮点数的运算，可输入两定点数或两个浮点数。浮点数格式为12.3E8（12.3e8） -float arithmetic, the importation of two set points, or 2 float. Float format to 12.3 E8 (12.3e8)

程序首先计算数值解，然后利用特征线法计算真解，最后计算一范数误差e1以及无穷范数误差e8-First calculate the numerical solution procedure, and then use the method of characteristics to calculate the true solution, the final calculation of an error e1 norm and infinity norm error e8