Variable may refer to:

Computer science

Variable (computer science) In computer programming, a variable is an abstract storage location paired with an associated symbolic name, which contains some known or unknown quantity of data or object referred to as a '' value''; or in simpler terms, a variable is a named ...

, a symbolic name associated with a value and whose associated value may be changed

Mathematics

Variable (mathematics) In mathematics, a variable (from Latin language, Latin ) is a Mathematical symbol, symbol, typically a letter, that refers to an unspecified mathematical object. One says colloquially that the variable ''represents'' or ''denotes'' the object, a ...

, a symbol that represents a quantity in a mathematical expression, as used in many sciences *

Propositional variable In mathematical logic, a propositional variable (also called a sentence letter, sentential variable, or sentential letter) is an input variable (that can either be true or false) of a truth function. Propositional variables are the basic building ...

, taking the value true or false in mathematical logic *

Random variable A random variable (also called random quantity, aleatory variable, or stochastic variable) is a Mathematics, mathematical formalization of a quantity or object which depends on randomness, random events. The term 'random variable' in its mathema ...

, a variable in statistics whose value depends on random events **

Categorical variable In statistics, a categorical variable (also called qualitative variable) is a variable that can take on one of a limited, and usually fixed, number of possible values, assigning each individual or other unit of observation to a particular group or ...

, taking one of a finite number of values in a statistical problem, such as the head or tail result of a tossed coin **

Independent and identically distributed random variables Independent or Independents may refer to: Arts, entertainment, and media Artist groups * Independents (artist group), a group of modernist painters based in Pennsylvania, United States * Independentes (English: Independents), a Portuguese artis ...

, statistically independent and having the same probability distribution * Fluent (mathematics), a time-varying quantity as coined by Isaac Newton in his early calculus *

State variable A state variable is one of the set of Variable (mathematics), variables that are used to describe the mathematical "state" of a dynamical system. Intuitively, the state of a system describes enough about the system to determine its future behavi ...

, used to describe the mathematical "state" of a dynamical system *

Slack variable In an optimization problem, a slack variable is a variable that is added to an inequality constraint to transform it into an equality constraint. A non-negativity constraint on the slack variable is also added. Slack variables are used in particu ...

, inserted to transform an inequality constraint in an optimization problem into an equality *

Dependent and independent variables A variable is considered dependent if it depends on (or is hypothesized to depend on) an independent variable. Dependent variables are studied under the supposition or demand that they depend, by some law or rule (e.g., by a mathematical function ...

, a variable classified according to whether or not it depends for its value on another variable of interest *

Free variables and bound variables In mathematics, and in other disciplines involving formal languages, including mathematical logic and computer science, a variable may be said to be either free or bound. Some older books use the terms real variable and apparent variable for f ...

, restricted or otherwise to a specified set of values, such as through a logical quantifier * Complex variable, the argument or value of a function of a complex number in

complex analysis Complex analysis, traditionally known as the theory of functions of a complex variable, is the branch of mathematical analysis that investigates functions of complex numbers. It is helpful in many branches of mathematics, including algebraic ...

Physical and social sciences

Variable (research) In science and research, an attribute is a quality of an object (person, thing, etc.). Earl R. Babbie, ''The Practice of Social Research'', 12th edition, Wadsworth Publishing, 2009, , p. 14-18 Attributes are closely related to variables. A variabl ...

, a logical set of attributes *

Control variable A control variable (or scientific constant) in scientific experimentation is an experimental element which is constant (controlled) and unchanged throughout the course of the investigation. Control variables could strongly influence experimental ...

, a measurable entity which is constant (controlled) and unchanged throughout the course of a scientific experiment *

Variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...

, a type of astronomical star

Other uses

* "

The Variable "The Variable" is the 14th television episode of the fifth season of '' Lost'', and the 100th episode overall. It originally aired on the American Broadcasting Company (ABC) in the United States on April 29, 2009. The hundredth episode milest ...

", an episode of the television series '' Lost''

Computer science

Mathematics

Physical and social sciences

Other uses

See also