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Widely used in many programs, e.g. it is used in Excel 2003 and later versions for the Excel function RAND [8] and it was the default generator in the language Python up to version 2.2. [9] Rule 30: 1983 S. Wolfram [10] Based on cellular automata. Inversive congruential generator (ICG) 1986 J. Eichenauer and J. Lehn [11] Blum Blum Shub: 1986
This module contains a number of functions that use random numbers. It can output random numbers, select a random item from a list, and reorder lists randomly. The randomly reordered lists can be output inline, or as various types of ordered and unordered lists. The available functions are outlined in more detail below.
Random numbers are frequently used in algorithms such as Knuth's 1964-developed algorithm [1] for shuffling lists. (popularly known as the Knuth shuffle or the Fisher–Yates shuffle, based on work they did in 1938). In 1999, a new feature was added to the Pentium III: a hardware-based random number generator.
Dice are an example of a mechanical hardware random number generator. When a cubical die is rolled, a random number from 1 to 6 is obtained. Random number generation is a process by which, often by means of a random number generator (RNG), a sequence of numbers or symbols that cannot be reasonably predicted better than by random chance is generated.
A C version [a] of three xorshift algorithms [1]: 4,5 is given here. The first has one 32-bit word of state, and period 2 32 −1. The second has one 64-bit word of state and period 2 64 −1.
The Lehmer random number generator [1] (named after D. H. Lehmer), sometimes also referred to as the Park–Miller random number generator (after Stephen K. Park and Keith W. Miller), is a type of linear congruential generator (LCG) that operates in multiplicative group of integers modulo n. The general formula is
For example, squaring the number "1111" yields "1234321", which can be written as "01234321", an 8-digit number being the square of a 4-digit number. This gives "2343" as the "random" number. Repeating this procedure gives "4896" as the next result, and so on. Von Neumann used 10 digit numbers, but the process was the same.
As an example, to find the sixth element of the above sequence, we'd write 6 = 1*2 2 + 1*2 1 + 0*2 0 = 110 2, which can be inverted and placed after the decimal point to give 0.011 2 = 0*2-1 + 1*2-2 + 1*2-3 = 3 ⁄ 8. So the sequence above is the same as