祖率

zǔlǜ

[the approximate ratio of the circumference of a circle to its diameter as calculated by Zu Chong Zhi][数]∶南北朝时祖冲之算出圆周率的近似值在3.1415926和3.1415927之间, 并指出圆周率的约率为22/7, 密率为355/113。 为了纪念祖冲之, 把他算出的近似值叫做祖率