Browse Definitions :

pseudo-random number generator (PRNG)

A pseudo-random number generator (PRNG) is a program written for, and used in, probability and statistics applications when large quantities of random digits are needed. Most of these programs produce endless strings of single-digit numbers, usually in base 10, known as the decimal system. When large samples of pseudo-random numbers are taken, each of the 10 digits in the set {0,1,2,3,4,5,6,7,8,9} occurs with equal frequency, even though they are not evenly distributed in the sequence.

Many algorithm s have been developed in an attempt to produce truly random sequences of numbers, endless strings of digits in which it is theoretically impossible to predict the next digit in the sequence based on the digits up to a given point. But the very existence of the algorithm, no matter how sophisticated, means that the next digit can be predicted! This has given rise to the term pseudo-random for such machine-generated strings of digits. They are equivalent to random-number sequences for most applications, but they are not truly random according to the rigorous definition.

The digits in the decimal expansions of irrational number s such as pi (the ratio of a circle's circumference to its diameter in a Euclidean plane), e (the natural- logarithm base), or the square roots of numbers that are not perfect squares (such as 2 1/2 or 10 1/2 ) are believed by some mathematicians to be truly random. But computers can be programmed to expand such numbers to thousands, millions, billions, or trillions of decimal places; sequences can be selected that begin with digits far to the right of the decimal (radix) point, or that use every second, third, fourth, or n th digit. However, again, the existence of an algorithm to determine the digits in such numbers is used by some theoreticians to argue that even these single-digit number sequences are pseudo-random, and not truly random. The question then becomes, Is the algorithm accurate (that is, random) to infinity, or not? -- and because no one can answer such a question definitively because it is impossible to travel to infinity and find out, the matter becomes philosophical.

This was last updated in March 2011
  • man in the browser (MitB)

    Man in the browser (MitB) is a security attack where the perpetrator installs a Trojan horse on the victim's computer that is ...

  • Patch Tuesday

    Patch Tuesday is the unofficial name of Microsoft's monthly scheduled release of security fixes for the Windows operating system ...

  • parameter tampering

    Parameter tampering is a type of web-based cyber attack in which certain parameters in a URL are changed without a user's ...

  • chief procurement officer (CPO)

    The chief procurement officer, or CPO, leads an organization's procurement department and oversees the acquisitions of goods and ...

  • Lean Six Sigma

    Lean Six Sigma is a data-driven approach to improving efficiency, customer satisfaction and profits.

  • change management

    Change management is a systematic approach to dealing with the transition or transformation of an organization's goals, processes...

  • clickstream data (clickstream analytics)

    Clickstream data and clickstream analytics are the processes involved in collecting, analyzing and reporting aggregate data about...

  • neuromarketing

    Neuromarketing is the study of how people's brains respond to advertising and other brand-related messages by scientifically ...

  • contextual marketing

    Contextual marketing is an online marketing strategy model in which people are served with targeted advertising based on their ...