Ο

Οmicrοn（/ˈoʊmɪkrɒn, ˈɒmɪkrɒn, oʊˈmaɪkrɒn/;^[1] 大寫Ο，小寫ο，中文音譯：奧米克戎^[2]、奧密克戎、歐米克隆）是第15個希臘字母。在希臘數字系統中，它的數值為70。這個字母來源於腓尼基字母ayin：。在古希臘語中，οmicrοn代表的發音是[o]，與omega [ɔː]和ου [oː]形成對立。在現代希臘語中，οmicrοn代表中後圓唇元音/o̞/ ，與omega同音。由οmicrοn產生的字母包括羅馬字母O和西里爾字母O。

用處

除了作為字母使用外，omicron偶爾也用於技術符號，但其用途有限，因為大寫和小寫（Ο ο）都與拉丁字母O無法區分，也難以與阿拉伯數字0區別。

數學

由Paul Bachmann在1894年提出、愛德蒙·蘭道在1909年推廣的大O符號，最初代表「order of」（"Ordnung"，階），因此是一個拉丁字母，顯然在1976年被高德納視為大寫的Omicron^[3]，可能是參考了他對符號（大寫）Omega的定義。Bachmann和蘭道都沒有稱它為「Omicron」，「Omicron」這個詞在克努特的論文中只出現過一次，而且只是在標題中。

希臘數字

在希臘語中，有幾種數字書寫系統；在古典時代後期，最常見的形式是用omicron（大寫或小寫）來代表70這個數值。

更為普遍的是，在任何希臘字母標記的列表中，字母omicron都被用來標記第15個序數的位置。因此，例如在歐幾里得的《幾何原本》中，當幾何圖中的各個點用字母標記時，實際上與用數字標記相同，每個字母代表其在標準字母表中的位置數字。^[a]^[b]

天文學

Omicron用於指定一個星座組中的第十五顆星，它的序數位置是星等和位置的不規則函數。^[4]^[5]這樣的恆星包括Omicron Andromedae、Omicron Ceti和Omicron Persei。

在克勞狄烏斯·托勒密（約約100–170）的《天文學大成》中，1 ... 59的六十進制數字表是以希臘數字的傳統方式^[c]表示： $'α$ ... $'νθ$ 。由於字母omicron[在標準系統中代表70（′ο）]在六進制中沒有使用，它被重新用於代表一個空的數字單元。在某些版本中，該單元格只是留有空白（那裡沒有東西=數值為零），但為了避免複製錯誤，人們傾向於用omicron標記一個零單元格，就像現代表格中的空白單元格用破折號（-）填充一樣。Omicron和破折號都意味著「這不是一個錯誤，這個單元格實際上應該是空的」。巧合的是，古代的零值omicron（ $ο$ ）類似於現代阿拉伯數字的零（0）。

用以命名冠狀病毒2型的變異株

2021年11月26日，世界衛生組織宣布COVID-19的一個新的變異株值得關注，根據世衛組織的命名系統命名為Omicron。B.1.1.529變異株於2021年11月24日在南非首次被測序。^[6]

字符編碼

Greek Omicron / Coptic O^[7]

字元	Ο		ο		Ⲟ		ⲟ
Unicode名稱	Greek Capital Letter Omicron		Greek Small Letter Omicron		Coptic Capital Letter O		Coptic Small Letter O
編碼	十進位	十六進位	十進位	十六進位	十進位	十六進位	十進位	十六進位
Unicode	405	U+039F	425	U+03BF	3304	U+2C9E	3305	U+2C9F
UTF-8	206 159	CE 9F	206 191	CE BF	226 178 158	E2 B2 9E	226 178 159	E2 B2 9F
UTF-16	927	039F	959	03BF	11422	2C9E	11423	2C9F
字符值引用	Ο	Ο	ο	ο	Ⲟ	Ⲟ	ⲟ	ⲟ
字符值引用	Ο		ο
DOS Greek	142	8E	166	A6
DOS Greek-2	190	BE	233	E9
Windows 1253	207	CF	239	EF

Mathematical Omicron^[8]

這些字符只作為數學符號使用。風格化的希臘文應使用正常的希臘字母進行編碼，用標記和文本格式來表示文本風格。

字元	𝚶		𝛐		𝛰		𝜊		𝜪		𝝄
Unicode名稱	Mathematical Bold Capital Omicron		Mathematical Bold Small Omicron		Mathematical Italic Capital Omicron		Mathematical Italic Small Omicron		Mathematical Bold Italic Capital Omicron		Mathematical Bold Italic Small Omicron
編碼	十進位	十六進位	十進位	十六進位	十進位	十六進位	十進位	十六進位	十進位	十六進位	十進位	十六進位
Unicode	23716	U+1D6B6	23730	U+1D6D0	23750	U+1D6F0	23710	U+1D70A	23730	U+1D72A	23744	U+1D744
UTF-8	240 157 154 182	F0 9D 9A B6	240 157 155 144	F0 9D 9B 90	240 157 155 176	F0 9D 9B B0	240 157 156 138	F0 9D 9C 8A	240 157 156 170	F0 9D 9C AA	240 157 157 132	F0 9D 9D 84
UTF-16	55349 57014	D835 DEB6	55349 57040	D835 DED0	55349 57072	D835 DEF0	55349 57098	D835 DF0A	55349 57130	D835 DF2A	55349 57156	D835 DF44
字符值引用	𝚶	𝚶	𝛐	𝛐	𝛰	𝛰	𝜊	𝜊	𝜪	𝜪	𝝄	𝝄

字元	𝝤		𝝾		𝞞		𝞸
Unicode名稱	Mathematical Sans-Serif Bold Capital Omicron		Mathematical Sans-Serif Bold Small Omicron		Mathematical Sans-Serif Bold Italic Capital Omicron		Mathematical Sans-Serif Bold Italic Small Omicron
編碼	十進位	十六進位	十進位	十六進位	十進位	十六進位	十進位	十六進位
Unicode	23764	U+1D764	23784	U+1D77E	23804	U+1D79E	23818	U+1D7B8
UTF-8	240 157 157 164	F0 9D 9D A4	240 157 157 190	F0 9D 9D BE	240 157 158 158	F0 9D 9E 9E	240 157 158 184	F0 9D 9E B8
UTF-16	55349 57188	D835 DF64	55349 57214	D835 DF7E	55349 57246	D835 DF9E	55349 57272	D835 DFB8
字符值引用	𝝤	𝝤	𝝾	𝝾	𝞞	𝞞	𝞸	𝞸

說明性腳註

^ Greek letters-as-numbers used an older Greek alphabet with three more otherwise unused letters, two of them re‑instated in their old locations, early in the alphabet. So positions higher than 5th place ( $ε$ ) were shifted from the standard alphabet; 5th place was marked with normal fifth letter epsilon ( $ε$ ). The 6th letter in the conventional alphabet, that normally follows $ε$ is $ζ$ (zeta) but the number 6 was represented a revived ancient letter $' ϝ$ (digamma), followed by $' ζ$ which was pushed up from 6th to its ancient position (7th) to represent the number 7. All of the letters after $ζ$ were likewise shifted up one place, until the second ancient letter koppa, ( $ϙ$ ), was reached; it fell between $π$ and $ρ$ . Ever letter from ρ to ω was shifted two places past its conventional ordinal position. Last place coming right after omega ( $ω$ , 800) was sampi ( $ϡ$ ) which represented 900. (From that point, the system restarted, with a new tick-mark, at $͵ α$ . The tick-mark was put in a different place ( $͵ α$ rather than $' α$ ) to show that the letter represented a multiple of 1,000 rather than 1.)
^ From Euclid up to the 19th century, mathematical and technical diagrams were habitually marked sequentially with letters (or numbers), whereas in modern mathematical and scientific diagrams, it is much more common to choose for markers letters that might remind readers of the word used to describe the item in question. For example, Feynman diagrams in particle physics label the positions of particles with the first letter of their name, either in the Latin or Greek alphabet. So $p$ , $n$ , and $e$ , represent the position on a diagram of a proton, neutron, and electron, respectively. The neutrino is represented by $ν$ (Greek "nu"), since the Latin letter " $n$ " is reserved for the neutron.
^ Sexagesimal Greek numbers in the Almagest are conventional: 1 2 3 4 5 6 7 8 9 $= 'α 'β 'γ 'δ 'ε ' ϝ'ζ 'η 'θ$ . Notice that ancient digamma ( $ϝ$ ) is used for 6 instead of zeta ( $ζ$ , which is used for 7) ; 10 20 30 40 50 $= 'ι 'κ 'λ 'μ 'ν$ . Adjacent number-letters add, so all the other numbers are made by letter pairs, such as 29 30 31 $= 'κθ 'λ 'λα$ . The number 59 ( $'νθ$ ) is the largest value used in a single cell in sexagesimal. That leaves xi ( $ξ$ ) and the letters following it $ξ ο π ϙ ρ σ τ υ φ χ ψ ω ϡ$ free for other use: Ptolemy picked $ο$ , which normally was used for 70, to mark empty (zero) cells, perhaps because the word for "nothing", $οὐδέν$ starts with an omicron.

參考文獻

^ omicron. 牛津英語詞典 (第三版). 牛津大學出版社. 2005-09 （英語）.
^ 希腊字母的汉字规范译音. 中國科技術語. 2003, 5 (03) [2021-11-30]. ISSN 1673-8578. （原始內容存檔於2021-09-21）. 奧米克戎
^ Knuth, Donald. Big Omicron and big Omega and big Theta (PDF). SIGACT News. April–June 1976, 8 (2): 18–24 [2021-11-28]. S2CID 5230246. doi:10.1145/1008328.1008329. （原始內容存檔 (PDF)於2021-11-30）.
^ Martin, Martha Evans. The Friendly Stars 1st. New York: Harper & Brothers Publishers. 1907: 135 [8 February 2016].
^ Wilk, Stephen R. Medusa: Solving the Mystery of the Gorgon 1st. New York, NY; London, UK: Oxford University Press. 2007: 201 [8 February 2016]. ISBN 9780199887736. （原始內容存檔於2022-01-30）.
^ Classification of Omicron (B.1.1.529): SARS-CoV-2 Variant of Concern. World Health Organization. [26 November 2021]. （原始內容存檔於2021-11-26）.
^ Greek and Coptic (Range: 0370–03FF) (PDF). The Unicode Standard, Ver. 8.0. Unicode, Inc. 2015 [8 February 2016]. （原始內容存檔 (PDF)於2022-02-15）.
^ Mathematical Alphanumeric Symbols (Range: 1D400–1D7FF) (PDF). The Unicode Standard, Ver. 8.0. Unicode, Inc. 2015 [8 February 2016]. （原始內容存檔 (PDF)於2021-10-16）.

外部連結

維基詞典中的詞條「Ο」
維基詞典中的詞條「ο」

[ordinal_greek_letters-4] Greek letters-as-numbers used an older Greek alphabet with three more otherwise unused letters, two of them re‑instated in their old locations, early in the alphabet. So positions higher than 5th place ( $ε$ ) were shifted from the standard alphabet; 5th place was marked with normal fifth letter epsilon ( $ε$ ). The 6th letter in the conventional alphabet, that normally follows $ε$ is $ζ$ (zeta) but the number 6 was represented a revived ancient letter $' ϝ$ (digamma), followed by $' ζ$ which was pushed up from 6th to its ancient position (7th) to represent the number 7. All of the letters after $ζ$ were likewise shifted up one place, until the second ancient letter koppa, ( $ϙ$ ), was reached; it fell between $π$ and $ρ$ . Ever letter from ρ to ω was shifted two places past its conventional ordinal position. Last place coming right after omega ( $ω$ , 800) was sampi ( $ϡ$ ) which represented 900. (From that point, the system restarted, with a new tick-mark, at $͵ α$ . The tick-mark was put in a different place ( $͵ α$ rather than $' α$ ) to show that the letter represented a multiple of 1,000 rather than 1.)

[diagrams-5] From Euclid up to the 19th century, mathematical and technical diagrams were habitually marked sequentially with letters (or numbers), whereas in modern mathematical and scientific diagrams, it is much more common to choose for markers letters that might remind readers of the word used to describe the item in question. For example, Feynman diagrams in particle physics label the positions of particles with the first letter of their name, either in the Latin or Greek alphabet. So $p$ , $n$ , and $e$ , represent the position on a diagram of a proton, neutron, and electron, respectively. The neutrino is represented by $ν$ (Greek "nu"), since the Latin letter " $n$ " is reserved for the neutron.

[why_omicron_is_available-8] Sexagesimal Greek numbers in the Almagest are conventional: 1 2 3 4 5 6 7 8 9 $= 'α 'β 'γ 'δ 'ε ' ϝ'ζ 'η 'θ$ . Notice that ancient digamma ( $ϝ$ ) is used for 6 instead of zeta ( $ζ$ , which is used for 7) ; 10 20 30 40 50 $= 'ι 'κ 'λ 'μ 'ν$ . Adjacent number-letters add, so all the other numbers are made by letter pairs, such as 29 30 31 $= 'κθ 'λ 'λα$ . The number 59 ( $'νθ$ ) is the largest value used in a single cell in sexagesimal. That leaves xi ( $ξ$ ) and the letters following it $ξ ο π ϙ ρ σ τ υ φ χ ψ ω ϡ$ free for other use: Ptolemy picked $ο$ , which normally was used for 70, to mark empty (zero) cells, perhaps because the word for "nothing", $οὐδέν$ starts with an omicron.

[1] ron. 牛津英語詞典 (第三版). 牛津大學出版社. 2005-09 （英語）.

[termcn-2] 希腊字母的汉字规范译音. 中國科技術語. 2003, 5 (03) [2021-11-30]. ISSN 1673-8578. （原始內容存檔於2021-09-21）. 奧米克戎

[knuth-3] Knuth, Donald. Big Omicron and big Omega and big Theta (PDF). SIGACT News. April–June 1976, 8 (2): 18–24 [2021-11-28]. S2CID 5230246. doi:10.1145/1008328.1008329. （原始內容存檔 (PDF)於2021-11-30）.

[martin-6] Martin, Martha Evans. The Friendly Stars 1st. New York: Harper & Brothers Publishers. 1907: 135 [8 February 2016].

[wilk-7] Wilk, Stephen R. Medusa: Solving the Mystery of the Gorgon 1st. New York, NY; London, UK: Oxford University Press. 2007: 201 [8 February 2016]. ISBN 9780199887736. （原始內容存檔於2022-01-30）.

[9] Classification of Omicron (B.1.1.529): SARS-CoV-2 Variant of Concern. World Health Organization. [26 November 2021]. （原始內容存檔於2021-11-26）.

[U0370-10] Greek and Coptic (Range: 0370–03FF) (PDF). The Unicode Standard, Ver. 8.0. Unicode, Inc. 2015 [8 February 2016]. （原始內容存檔 (PDF)於2022-02-15）.

[U1D400-11] Mathematical Alphanumeric Symbols (Range: 1D400–1D7FF) (PDF). The Unicode Standard, Ver. 8.0. Unicode, Inc. 2015 [8 February 2016]. （原始內容存檔 (PDF)於2021-10-16）.

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