Overline

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The term overline denotes the Unicode - characters U + 203E ( english overline ) and U + 0305 ( combining overline , English for "Recombinant overline"). The graphic highlighting of one or more words with a continuous line above the characters is also known as overlining . Depending on the context in which the overline is used, it has a different meaning.

Colloquially, the overline is also known as the “upper line”. This designation is ambiguous and classically means the apostrophe .

Available characters

There is a character U + 00AF (175 dec ) in several character sets of the ISO 8859 family of standards and derived from it in the Unicode standard , which can be used both as an overline and as a macron . In the under MS-DOS -spread code page 850 of this character is in position 238 dec to find.

One of the reasons why the overline is often incorrectly referred to as a “ macron ” is not to be confused with the other Unicode characters of this name. The characters at the code points U + 02C9 ( modifier letter macron ) and U + 0304 ( combining macron ) are significantly shorter than their counterparts with overline .

The symbols marked with combining merge with the preceding letter (example: 0.1̅), whereas the code points U + 00AF and U + 203E ( overline ) always function as independent characters (example: 0.1¯ or 0.1‾) .

use

In mathematics, the overline is often used to indicate the periodicity of a number. Since it is not always possible to format the number so that the overline is above a certain digit (i.e. 3, 3 ), it is often used like this: 3,  3 (read: 3 period 3) for 3.33333333333 ... or 3.12  34 for 3.123434343434… (i.e. the digits after the overbar are repeated periodically). The overline indicates that the periodic part of the number comes after it.

In addition, the complex conjugate number is shown with the overline.

The overline is also used in electronic documents and when marking statistical mean values (for example ).

In the past, the overline was also used in text documents to indicate duplication of letters . The purpose was to save space. The use above the particularly wide "m" was therefore particularly common, which also improved legibility in the graphically monotonous fonts Fraktur and Kurrent . A tick had to be written above the current "u", which some writers sometimes adopted as a simple overline in the Latin script .

The abbreviation "No." for (lat. numero ) number, especially house number, used to be written even shorter with an overline instead of a dot "Nō".

In an economic context, the overline sometimes expresses that an amount is considered to be fixed (e.g. in, p. 241).

Generation in text software

  • In HTML documents, the characters can be created with ‾, ¯( decimal ¯ ) and ̅( ̅).
  • In TeX, you can \overline{ABC}overline with, whereby spaces are to be written as " \ " and umlauts as " \ddot a". There is also \bar xor \bar{x}, which uses an overline of a fixed length slightly narrower than a half square .
  • In Microsoft Windows , the character can be inserted across programs with the key sequence Alt+ 0175.
  • In LibreOffice , a single character can be swept over by pressing StrgShiftu+ 0305after typing the character.

Longer overlined texts, such as 0, 123, can also be created in some word processing programs as a font as a special form of underlining. A stylesheet instruction such as in can be used in HTML documents 0,<span style="text-decoration: overline;">123</span>.

See also

Individual evidence

  1. ↑ Marcel Clermont, Magnus Richter: Knowledge-imparting services at universities - approaches to a new conception of production theory based on the constructivist learning paradigm . In: Heinz Ahn, Marcel Clermont, Rainer Souren (eds.): Sustainable decision-making - contributions to multi-perspective performance management of value-added processes . Springer Gabler, Wiesbaden 2016, ISBN 978-3-658-12505-9 , pp. 231-248 .