虽然系统有给出划圆的直接的函数，但是没有让读者了解具体的计算机系统内部的绘制过程，本程序以顺圆为例，以逐点逼近法画出了并且是可以从任意点开始的顺圆的程序-Although the system is given a round of direct function, but did not allow the reader to understand the specific computer systems within the mapping process, the procedures to Shun Yuen example, the point-by-painted with the approximation and can be started from any point of Shun Yuen procedures