Index

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For the use of the word "index" in Wikipedia, see WP:INDEX

An index is an indirect shortcut derived from and pointing into, a greater volume of values, data, information or knowledge. Index may refer to:

Business[edit]

Publishing[edit]

  • Bibliographic index, a regularly updated print periodical publication that lists articles, books, and/or other information items, usually within a particular discipline
  • Index (publishing), a detailed list, usually arranged alphabetically, of the specific information in a publication
  • Index (typography), a (rare today) punctuation mark
  • Index cards in a rolodex, an old library card catalog or other organizational purpose, usually but not always 3" x 5", early and mid-20th century technologies for maintaining list of information, and in the card catalog also useful for cross-referencing information
  • Germany's List of Media Harmful to Young People, colloquially known as The Index, published by the Bundesprüfstelle für jugendgefährdende Medien
  • Index Librorum Prohibitorum, a list of publications which the Catholic Church censored (translates loosely from Latin as : "Banned Book List")
  • Index Librorum Prohibitorum, a character from the Japanese light novel, anime and manga A Certain Magical Index. "Index" may refer either to the character or the series
  • Index Magazine, a New York City-based publication for art and culture
  • Index on Censorship, a publishing organization that campaigns for freedom of expression, produces a quarterly magazine of the same name
  • index.hu, a Hungarian-language news and community portal
  • Indexed (cartoon), a Web cartoon by Jessica Hagy
  • The Index, the student newspaper of Kalamazoo College
  • The Index (journal), a European propaganda journal created by Henry Hotze to support the Confederate States of America during the American Civil War or, a European informational journal supporting the rebellion against the United States of America during the War Between the States.
  • Thumb index, a round cut-out in the pages of a publication
  • Truman State University Index, the weekly student newspaper of Truman State University

Sciences[edit]

Biological sciences[edit]

  • Diversity index – a quantitative measure that increases when the number of types (distinct groups) into which a set of entities (a population) has been classified increases, and obtains its maximum value for a given number of types when all types are represented proportional to their number within the set of entities

Computer science[edit]

Economics[edit]

  • Index (economics), a single number calculated from an array of prices and quantities
    • Price index, a typical price for some good or service

Geography[edit]

Library and information science[edit]

Linguistics[edit]

  • Indexicality, the variation of meaning of an utterance according to certain features of the context in which it is uttered

Mathematics[edit]

  • A number or other symbol that indicates the location of a variable in an indexed family or set such as a list or array of numbers or other mathematical objects, usually written as a subscript to the variable; e.g. in the list \lbrace x_1, x_2, x_3, x_4\rbrace, the number 3 is the index of the third element, x_3.
  • A numerical value attached to a mathematical object, such as those listed here under Algebra and Analysis
  • The index of summation i is used to calculate a sum, e.g.:
\sum_{i \mathop =3}^5 i = 3+4+5 = 12.

Algebra[edit]

  • The degree of an nth root
  • The index of a subgroup is the number of a subgroup's left cosets (which is equal to the number of its right cosets).
  • The index of a linear map, is the dimension of the map's kernel minus the dimension of its cokernel.
  • The index of a real quadratic form Q is defined (but not always consistently) as pq, where Q can be written as a difference of p squared linear terms and q squared linear terms.
  • The index of a matrix is the least integer k ≥ 0 such that {{{1}}}.

Analysis[edit]

  • The winding number of an oriented closed curve on a surface relative to a point on that surface; loosely speaking, the number of times the curve goes around the point counter-clockwise
  • The index of a vector field v at an isolated zero is the degree of the map x^a \mapsto \frac{v^a(x)}{\sqrt{\sum_b(v^b(x))^2}}, taking points near the zero into the unit sphere.

Technologies[edit]

Mechanics[edit]

  • Indexing (motion), a kind of motion in many areas of mechanical engineering and machining

Optics[edit]

Other usages[edit]