dwStart = GetTickCount();
{}
dwEnd = GetTickCount();
cout << "The atan run time is:" << (dwEnd - dwStart) << "ms!" << endl;//输出运行时间
dwStart = GetTickCount();
{}
dwEnd = GetTickCount();
cout << "The atan run time is:" << (dwEnd - dwStart) << "ms!" << endl;//输出运行时间