This paper seeks the algorithm to converge to the minimum zone,using the moving direction and step width to minish the radius.

• 本文另辟途径,直接以降低同心球半径之差为目标,寻求球心的移动方向和移动步长,不断把半径之差减小,从而使球度误差的计算向"最小区域"收敛。