Degree symbol
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The degree symbol (°) is a typographical symbol that is used, among other things, to represent degrees of arc (e.g. in geographic coordinate systems), hours (in the medical field), degrees of temperature, alcohol proof, or diminished quality in musical harmony.[1] The symbol consists of a small raised circle, historically a zero glyph.
In Unicode it is encoded at U+00B0 ° DEGREE SIGN (°).
History
The first known recorded modern use of the degree symbol in mathematics is from 1569[2] where the usage seems to show that the symbol is a small raised zero, to match the prime symbol notation of sexagesimal subdivisions of degree such as minute ′, second ″, and tertia ‴ which originates as small raised Roman numerals.
Typography
In the case of degrees of arc, the degree symbol follows the number without any intervening space.
In the case of degrees of temperature, three scientific and engineering standards bodies (BIPM, ISO and the U.S. Government Printing Office) prescribe printing temperatures with a space between the number and the degree symbol, as in 10 °C.[3][4] However, in many works with professional typesetting, including scientific works published by the University of Chicago Press or Oxford University Press, the degree symbol is printed with no spaces between the number, the symbol, and the Latin letters "C" or "F" representing Celsius or Fahrenheit, respectively (as in 10°C).[5][6] This is also the practice of the University Corporation for Atmospheric Research, which operates the National Center for Atmospheric Research.[7] Though not recommended, use of the degree symbol without a following Latin letter is done so without a space between the number and symbol; this is considered more acceptable if the standard of temperature is not known, but it is recommended in this case that the full word, rather than the symbol for degrees, be used. Use of the degree symbol to refer to temperatures measured in kelvins (symbol: K) was abolished in 1967 by the 13th General Conference on Weights and Measures (CGPM). Therefore, the triple point of water, for instance, is correctly written today as simply 273.16 K. The SI fundamental temperature unit is now "kelvin" (note the lower case), and no longer "degree Kelvin".
Encoding
The degree sign is included in Unicode as U+00B0 ° DEGREE SIGN (°).
For use with Chinese characters there are also code points for U+2103 ℃ DEGREE CELSIUS and U+2109 ℉ DEGREE FAHRENHEIT.
The degree sign was missing from the basic 7-bit ASCII set of 1963, but in 1987 the ISO/IEC 8859 standard introduced it at position 0xB0 (176 decimal) in the Latin-1 variant. In 1991 the Unicode standard incorporated all of the Latin-1 code points, including the degree sign.
The Windows Code Page 1252 was also an extension of the Latin-1 standard, so it had the degree sign at the same code point. The code point in the older DOS Code Page 437 was 0xF8 (248 decimal).
Lookalikes
Other characters with similar appearance but different meanings include:
- U+00BA º MASCULINE ORDINAL INDICATOR (º) (superscript letter used in abbreviating words; varies with the font and sometimes underlined)
- U+02DA ˚ RING ABOVE (˚) (standalone)
- U+030A ◌̊ COMBINING RING ABOVE (applied to a letter)
- U+0325 ◌̥ COMBINING RING BELOW (applied to a letter)
- U+309C ゜ KATAKANA-HIRAGANA SEMI-VOICED SOUND MARK (standalone)
- U+309A ◌゚ COMBINING KATAKANA-HIRAGANA SEMI-VOICED SOUND MARK (applied to a letter)
- U+2070 ⁰ SUPERSCRIPT ZERO
- U+2218 ∘ RING OPERATOR (∘, ∘)
Keyboard entry
Some computer keyboard layouts, such as the QWERTZ layout as used in Germany, Austria and Switzerland, and the AZERTY layout as used in France and Belgium, have the degree symbol available directly on a key. But the common keyboard layouts in English-speaking countries do not include the degree sign, which then has to be input some other way. The method of inputting depends on the operating system being used.
On the Colemak keyboard layout, one can press AltGr+\ followed by D to insert a degree sign.
With Microsoft Windows, there are several ways to make the degree symbol:
- One can type Alt+248 or Alt+0176
Note: "0176" is different from "176"; Alt+176 produces the light shade (░) character.
Note: The NumLock must be set first; on full size keyboards, the numeric keypad must be used; on laptops without a numerical keypad, the virtual numeric keypad must be used (often requiring that the Fn key be held down as the numeric sequence is typed). - The Character Map tool also may be used to obtain a graphical menu of symbols.
- The US-International English keyboard layout creates the degree symbol with AltGr+⇧ Shift+;
In Microsoft Office and similar programs, there is often also an Insert menu with an Insert Symbol or Symbol command that brings up a graphical palette of symbols to insert, including the degree symbol. In WordPerfect, pressing Ctrl+W+ brings up lists of special characters.
In the classic Mac OS and macOS operating systems, the degree symbol can be entered by typing ⌥ Opt+⇧ Shift+8. One can also use the Mac OS character palette, which is available in many programs by selecting Special Characters from the Edit Menu, or from the Input Menu (flag) icon on the menu bar (enabled in the International section of the System Preferences).
In iOS, the degree symbol is accessed by pressing and holding 0 and dragging your finger to the degree symbol. This procedure is the same as entering diacritics on other characters.
In LaTeX, the packages gensymb or textcomp that provides the commands \degree or \textdegree, respectively. In the absence of these packages one can write the degree symbol as ^{\circ} in math mode. In other words, it is written as the empty circle glyph \circ as a superscript.
In Linux operating systems such as Ubuntu, this symbol may be entered via the Compose key followed by o, o. Some keyboard layouts print this symbol upon pressing AltGr+⇧ Shift+0 (once or twice, depending on specific keyboard layout), and, in programs created by GTK+, one can enter Unicode characters in any text entry field by first pressing Ctrl+⇧ Shift+U+Unicode, regardless of keyboard layout. For the degree symbol, this is done by entering Ctrl+⇧ Shift+UB0.
See also
References
- ^ "Chord Symbols". Retrieved 2013-12-16.
- ^ *Cajori, Florian (1993) [1928-1929], A History of Mathematical Notations, Dover Publications, ISBN 0-486-67766-4
- ^ The International System of Units (PDF) (8th ed.), Bureau International des Poids et Mesures, 2006
- ^ Style Manual (PDF) (30th ed.), United States Government Printing Office, 2008
- ^ 9.16 Abbreviations and symbols, Chicago Manual of Style (15th ed.), University of Chicago, 2010
- ^ 10.52 Miscellaneous technical abbreviations, Chicago Manual of Style (15th ed.), University of Chicago, 2010
- ^ UCAR, UCAR Communications Style Guide, retrieved 2007-09-01