Constant

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A constant in mathematics is an amount that does not change, over time or otherwise: it is a fixed value. In most fields of discourse the term is an antonym of "variable", but in mathematical parlance a mathematical variable may sometimes also be called a constant.

More particularly, the term constant has several uses:

• In mathematics and computer science:
  • Mathematical constant, a number that arises naturally in mathematics, such as π and e
  • A coefficient or other parameter in a formula; given as a number or as a variable, but not being considered one of the arguments
  • The constant term of a polynomial (the term of degree 0)
  • A constant function (a function that maps all arguments to one same value)
  • The constant of integration, usually denoted by C and expressing a free parameter arising in integration
  • Logical constant, a symbol in symbolic logic that has the same meaning in all models, such as the symbol "=" for "equals"
  • Constant (programming), a name for a value that, unlike a variable, cannot be reassociated with a different value
  • Constant time, or O(1) time, in computational complexity theory, meaning a computation time needed for solving a problem that does not depend on the size of the input data
  • Exact trigonometric constants
• In physics and chemistry:
  • Physical constant, a physical quantity that is generally believed to be both universal in nature and constant in time, such as c, the speed of light, or h, the Planck constant
  • Cosmological constant, usually denoted by Λ, a parameter modifying the original equations of the theory of general relativity, introduced by Einstein and important for determining the ultimate fate of the universe as predicted by the theory
  • Time constant, usually denoted by τ, a value characterizing the frequency response of a first-order, linear time-invariant system
  • Reaction rate constant, often denoted k or λ, a value characterizing the speed of a chemical reaction
• People named Constant:
  • Constans, a Roman Emperor who ruled from 337 to 350
  • Constant Nieuwenhuys, a painter and member of the Situationist International
  • Constant (given name)
  • Constant (surname)

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