Английская Википедия:Division sign
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The division sign (Шаблон:Char) is a mathematical symbol consisting of a short horizontal line with a dot above and another dot below, used in Anglophone countries to indicate the operation of division. This usage, though widespread in some countries, is not universal and the symbol has a different meaning in other countries. Its use to denote division is not recommended in the ISO 80000-2 standard for mathematical notation.[1]
In mathematics
The obelus, a historical glyph consisting of a horizontal line with (or without) one or more dots, was first used as a symbol for division in 1659, in the algebra book Шаблон:Lang by Johann Rahn, although previous writers had used the same symbol for subtraction.[2] Some near-contemporaries believed that John Pell, who edited the book, may have been responsible for this use of the symbol.[2] Other symbols for division include the slash or solidus Шаблон:Char, the colon Шаблон:Char, and the fraction bar (the horizontal bar in a vertical fraction).[3][4] The ISO 80000-2 standard for mathematical notation recommends only the solidus Шаблон:Char or "fraction bar" for division, or the "colon" Шаблон:Char for ratios; it says that the Шаблон:Char sign "should not be used" for division.[1]
In Italy, Poland and Russia, the Шаблон:Char sign was sometimes used to denote a range of values, and in Scandinavian countries it was used as a negation sign.[5]
The same symbol has been used to represent subtraction in north-eastern Europe: the Unicode Consortium has allocated a separate code point, Шаблон:Unichar for this usage uniquely;[6][7] the exact form of the symbol displayed is typeface (font) dependent.
In computer systems
Encoding
The symbol was assigned to code point 0xF7 in ISO 8859-1, as the "division sign". This encoding was transferred to Unicode as U+00F7.[8] In HTML, it can be encoded as Шаблон:Code or Шаблон:Code (at HTML level 3.2), or as Шаблон:Code.
Keyboard entry
In Microsoft Windows, this division sign is produced with Alt+0247 (or 246 with no zero) on the number pad, or by pressing Шаблон:Key press when an appropriate keyboard layout is in use. In classic Mac OS and macOS, it is produced with Шаблон:Key press.
On UNIX-based systems using Screen or X with a Compose key enabled, it can be produced by composing Шаблон:Key press (colon) and Шаблон:Key press (hyphen/minus). It may also be produced using its Unicode code-point (F7), by pressing Шаблон:Key pressШаблон:NbspШаблон:Keypress.
In LaTeX, the division sign is obtained by the command Шаблон:Code.
In ChromeOS (with International/Extended keyboard setting), the division sign is obtained by pressing Шаблон:Keypress. Otherwise, the Unix-style methods may be used.
See also
Notes
External links
- Jeff Miller: Earliest Uses of Various Mathematical Symbols
- Michael Quinion: Where our arithmetic symbols come from
- ↑ 1,0 1,1 ISO 80000-2, Section 9 "Operations", 2-9.6
- ↑ 2,0 2,1 Шаблон:Cite book pp 270,271
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite book
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ Шаблон:Citation
