Von Neuman在1940年提出了平方取中法，其原理是将一个给定的2n比特的数平方，然后高位补0得到4n比特的数，再截取中间的2n位进行下次迭代，并得到一个随机数序列。这种方法无论是在硬件实现上，还是在仿真测试上都比较容易实现，但是它的周期受初始值的影响很大，如果初始值选得不好，会严重影响随机数序列的质量和周期，而且其最大周期不会超过22n

随机数生成-Von Neuman in the 1940 square from France, Its principle is to be a set of two n-bit a few square, and then high-0 4 n is the number of bits. Interception again among the two n-for the next iteration, and with a random number sequence. This method both in hardware, or on the simulation test will be relatively easy to achieve. However, its initial value by the cycle of a great value if the initial election properly, will seriously affect random number sequences of the quality and cycle, but its biggest cycle will not exceed 22 n Random Number Generation