说明：  levy飞行的2D演示，求解一个2维的方程，2万次迭代可以搜索到最优解。可对levy飞行有直观的了解(plot绘图显示)。自己编写的代码，初学者可以借鉴。
(Levy flight of the 2D demo, solving a 2-dimensional equation, 2 million iterations can search for the optimal solution. Levy flight can have an intuitive understanding (plot graphics display). Prepared their own code, beginners can learn from.)