说明：  圆度误差计算，国际上常用的有4种方法：最小二乘圆(LSC)方法；最大内切圆(MIC)方法；最小外接圆(MCC)方法和最小区域圆(MZC)方法。
(On the roundness error of calculation, the international commonly used there are four methods: least square circle method (LSC) The maximum inscribed circle (MIC) method Minimum inscribed circle (MCC) method and minimum zone circles (MZC) method.)