朱丽叶！哈哈！随机数都是伪随机的，已经提前设置好的。

同问！！

谢谢啦

生成伪随机数时指定的随机抽样起点。这个seed的选取是随意的，只要你设置的seed是一样的，就保证得到同样的一组随机模拟数据。
Random-number functions and CALL routines generate streams of pseudo-random numbers from an initial starting point, called a seed, that either the user or the computer clock supplies. A seed must be a nonnegative integer with a value less than 231-1 (or 2,147,483,647). If you use a positive seed, you can always replicate the stream of random numbers by using the same DATA step. If you use zero as the seed, the computer clock initializes the stream, and the stream of random numbers cannot be replicated.

thank you