zeroth period of iterated function

例句：

1. 1.The zeroth period of the function is the point where it starts.
   函数的第一周期是它开始的地方。
2. 2. The zeroth term in a series is the first term.
   序列中的零项是第一个项。
3. 3. In mathematics, the zeroth root is the number that multiplies to 1.
   在数学中，零次根是乘以1的数字。