Xi
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224966368
2008-07-11T06:07:15Z
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{{wiktionarypar2|Ξ|ξ}}
{{Table_Greekletters|letter=xi}}
'''Xi''' (uppercase '''Ξ''', lowercase '''ξ''') is the 14th letter of the [[Greek alphabet]]. It is {{pronounced|ksi}} in [[Modern Greek]], and generally {{pronEng|ˈsaɪ}} (UK) or {{IPA|/ˈzaɪ/}} (US) in [[English language|English]].
In the system of [[Greek numerals]], it has a value of 60. In the system of [[Roman numerals]], it has a value of 11. The Xi is not to be confused with the letter [[Chi (letter)|Chi]], which takes the form of the Latin letter [[X]]. In ancient times, the [[Western Greek alphabet]] used it to represent {{IPA|/kʰ/}}, while it was used to represent /ks/ in other alphabets. As the alphabet was standardized, Xi was decided to be used for /ks/ and Chi for {{IPA|/kʰ/}}. While having no Latin derivative, the Xi was adopted into the [[early Cyrillic alphabet]], as the letter [[ksi]] ({{Unicode|Ѯ}}, {{Unicode|ѯ}}).
The lower-case letter ξ is used as a symbol for
[[Image:Xi alternate.png|frame|left|A joined variant of Ξ.]]
*[[random variable]]s;
*[[extent of reaction]] (a topic found most often in [[chemical engineering]] kinetics);
*[[eigenvector]]s;
*a parameter in a [[Pareto distribution#generalized Pareto distribution|generalized Pareto distribution]];
*the symmetric function equation of the [[Riemann zeta function]] in [[mathematics]], also known as the [[Riemann Xi function]];
*the [[damping factor]] in an [[RLC circuit]];
*a universal set in the [[set theory]];
*a number used in the error term of [[Newton–Cotes formulas]] that falls between ''a'' and ''b'';
*one of the two different polypeptide chains of the human embryonic [[hemoglobin]] types Hb-Portland (ξ<sub>2</sub>γ<sub>2</sub>) and Hb-Gower I (ξ<sub>2</sub>ε<sub>2</sub>);
*the [[correlation function (astronomy)|correlation function]] in [[astronomy]];
*frequency;
*a small displacement in MHD [[plasma stability]] theory.
*ξ・∀・)
The upper-case letter Ξ is used as symbol for
*The '[[Xi (particle)|cascade particles]]' in particle physics;
*indicating "no change of state" in [[Z notation]].
[[Category:Greek letters]]
[[als:Ξ]]
[[ar:كشي (حرف إغريقي)]]
[[arc:Ξ]]
[[br:Xi (lizherenn)]]
[[bg:Кси]]
[[ca:Xi]]
[[cy:Xi]]
[[da:Xi (bogstav)]]
[[de:Xi]]
[[el:Ξι]]
[[eo:Ksio]]
[[es:Ξ]]
[[eu:Xi]]
[[fr:Xi]]
[[ga:Xí]]
[[gd:Xi]]
[[gl:Xi]]
[[ko:Ξ]]
[[hr:Ksi]]
[[id:Xi]]
[[is:Xí]]
[[it:Xi (lettera)]]
[[he:קסי]]
[[ka:ქსი (ასო)]]
[[ht:Ξ]]
[[ku:Xi]]
[[la:Xi]]
[[lt:Ksi (raidė)]]
[[hu:Kszi]]
[[ms:Xi]]
[[nl:Xi (letter)]]
[[ja:Ξ]]
[[no:Xi]]
[[nn:Xi]]
[[nds:Xi]]
[[pl:Ksi]]
[[pt:Ξ]]
[[ru:Кси (буква)]]
[[sk:Ksí]]
[[sl:Ksi]]
[[sh:Ksi]]
[[fi:Ksii]]
[[sv:Xi]]
[[th:ไซ (อักษรกรีก)]]
[[tr:Ξ]]
[[uk:Ксі (літера)]]
[[zh:Ξ]]