Java生成“随机”数字不重复2 ^ 48周期 [英] Java generating "random" numbers that don't repeat for 2^48 period

问题描述

基本上我想生成随机数，这些数字在很长一段时间内都不会重复（我不想使用序列），例如java使用的LCG：

Basically I want to generate random numbers that won't ever repeat for a very long period (I don't want to use a sequence) like for example the LCG that java uses:

 synchronized protected int next(int bits) {
       seed = (seed * 0x5DEECE66DL + 0xBL) & ((1L << 48) - 1);
       return (int)(seed >>> (48 - bits));
 }

据我所知，这种情况下的种子只会在2 ^ 48个电话后重复下一步是正确的吗？

As I understand the seed in this case will only repeat after 2^48 calls to next is this correct?

所以我理解如果我做了一个方法：

so it is my understand that if I did a method like:

 synchronized protected long next() {
       seed = (seed * 0x5DEECE66DL + 0xBL) & ((1L << 48) - 1);
       return seed;
 }

保证种子值在2 ^ 48个电话之前不重复？

The seed value is guaranteed not to repeat before 2^48 calls?

推荐答案

不适用于那个LCG，因为每次调用时你都会被2 ^ 48修改（因此周期/状态是最多2 ^ 48的长度）。如果你想要一个更好的随机数生成器，你可以尝试Mersenne twister：

Not for that LCG, since you are modding out by 2^48 each time you call it (and thus the period/state is at most 2^48 in length). If you want a better random number generator, you could try the Mersenne twister:

http://en.wikipedia.org/wiki/Mersenne_twister

标准MT19937的周期为2 ^ 19937-1 （!!!）这应该比你需要的更多。

The standard MT19937 has a period of 2^19937-1 (!!!) That should be more than you will ever need.

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