In mathematics and statistics, a random number is either
Pseudo-random
A pseudorandom sequence of numbers is one that appears to be statistically random, despite having been produced by a completely deterministic and repeatable process.
Background
The generation of random numbers has many uses, such as for rando ...
or a number generated for, or part of, a set exhibiting
statistical randomness A numeric sequence is said to be statistically random when it contains no recognizable patterns or regularities; sequences such as the results of an ideal dice roll or the digits of π exhibit statistical randomness.
Statistical randomness does ...
.
Algorithms and implementations
A 1964-developed
algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
is popularly known as ''the
Knuth shuffle'' or ''the
Fisher–Yates shuffle'' (based on work they did in 1938). A real-world use for this is sampling water quality in a
reservoir
A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation.
Reservoirs can be created in a number of ways, including contro ...
.
In 1999, a new feature was added to the
Pentium III
The Pentium III (marketed as Intel Pentium III Processor, informally PIII or P3) brand refers to Intel's 32-bit x86 desktop and mobile CPUs based on the sixth-generation P6 microarchitecture introduced on February 28, 1999. The brand's initial ...
: a hardware-based
random number generator
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. This means that the particular outc ...
.
[
] It has been described as "several
oscillators combine their outputs and that odd waveform is sampled asynchronously." These numbers, however, were only 32 bit, at a time when export controls were on 56 bits and higher, so they were not state of the art.
Common understanding
In common understanding, "1 2 3 4 5" is not as random as "3 5 2 1 4" and certainly not as random as "47 88 1 32 41" but "we can't say authoritavely that the first sequence is not random ... it could have been generated by chance."
[
]
When a police officer claims to have done a "random .. door-to-door" search, there is a certain expectation that members of a jury will have.
[A pre-compiled list of apartment numbers would be a violation thereof.]
Real world consequences
Flaws in ''randomness'' have real-world consequences.
A 99.8% randomness was shown by researchers to negatively affect an estimated 27,000 customers of a large service
[ and that the problem was not limited to just that situation.
]
See also
* Algorithmically random sequence
Intuitively, an algorithmically random sequence (or random sequence) is a Sequence#Infinite sequences in theoretical computer science, sequence of binary digits that appears random to any algorithm running on a (prefix-free or not) universal Turi ...
* Quasi-random sequence
* Random number generation
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. This means that the particular out ...
* Random sequence The concept of a random sequence is essential in probability theory and statistics. The concept generally relies on the notion of a sequence of random variables and many statistical discussions begin with the words "let ''X''1,...,''Xn'' be independ ...
* Random variable
* Random variate
In probability and statistics, a random variate or simply variate is a particular outcome of a ''random variable'': the random variates which are other outcomes of the same random variable might have different values ( random numbers).
A random ...
* Random real
References
Permutations
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