A subroutine that returns the value of a single variable, and that usually has a single exit, for example, subroutines that compute mathematical functions, such as sine, cosine, logarithm, or that compute the maximum of a set of numbers.

• 一种子例行程序，它返回一个单独变量值，通常只有一个出口。例如计算数学函数的子例程，像正弦、余弦、对数等，又如求一组数的最大值的子例程。