说明：  Matlab里面没有提供直接以半径和圆心位置画圆的程序，该程序可以实现此功能，命令格式为：circle(radius,x0,y0, color )
(Matlab which does not provide the location directly in the center circle radius and the program, the program can achieve this functionality, the command format is: circle (radius, x0, y0, color ))