recursive definition of function

例句：

1. 1. The algorithm is recursivein nature and can be easily implemented.
   这个算法是递归性质的，很容易实现。
2. 2. Theprocess of recursion is akinto the way we think about problems.
   递归的过程类似于我们思考问题的方式。
3. 3. The functioncalls itself repeatedly until it reaches a basecase.
   函数反复调用自身，直到达到一个基本情形。