解决dtd和滚动条鼠标颜色控制css冲突的问题 -Dtd, and scroll the mouse to solve the color control css conflict, problem-solving dtd and the mouse scroll bar css color control the issue of conflict

计算器功能实现，基本解决问题-Calculator function realization, the basic problem-solving /////////////

差分格式的构造和选择是CFD的关键，选择MacCormack格式-One dimensional Riemann problem solving