Xi (letter)

Get Xi Letter essential facts below. View Videos or join the Xi Letter discussion. Add Xi Letter to your PopFlock.com topic list for future reference or share this resource on social media.

## Greek

## Cyrillic

## Mathematics and science

### Uppercase

#### Pure mathematics

#### Physics

#### Other uses

### Lowercase

#### Pure mathematics

#### Physics and astronomy

#### Other uses

## Character encodings

## Other uses

## References

This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.

Xi Letter

Greek alphabet |
---|

History |

Use in other languages |

Related topics |

**Xi** ^{[1]} (uppercase **?** or **?**, lowercase **?**; Greek: ) is the 14th letter of the Greek alphabet. It is pronounced [ksi] in Modern Greek, and generally or in English.^{[2]} In the system of Greek numerals, it has a value of 60. Xi was derived from the Phoenician letter samekh .

Xi is distinct from the letter chi, which gave its form to the Latin letter X.

Both in classical Ancient Greek and in Modern Greek, the letter ? represents the consonant cluster /ks/. In some archaic local variants of the Greek alphabet, this letter was missing. Instead, especially in the dialects of most of the Greek mainland and Euboea, the cluster /ks/ was represented by ? (which in classical Greek is chi, used for /k?/). Because this variant of the Greek alphabet was used in Italy, the Latin alphabet borrowed ? rather than ? as the Latin letter that represented the /ks/ cluster that was also present in Latin.

While having no Latin derivative, the Xi was adopted into the early Cyrillic alphabet, as the letter ksi (?, ?).

The uppercase letter ? is used as symbol in various contexts.

- Harish-Chandra's ? function in harmonic analysis and representation theory
- The Riemann Xi function in analytic number theory and complex analysis

- The "cascade particles" in particle physics
- The partition function under the grand canonical ensemble in statistical mechanics

- Indicating "no change of state" in Z notation in computing
- Monetary units of the cryptocurrency Ether, equal to 10
^{18}Wei

The lowercase letter ? is used as a symbol for:

- Random variables
- A parameter in a generalized Pareto distribution
- The symmetric function equation of the Riemann zeta function in mathematics, also known as the Riemann Xi function
- A universal set in set theory
- A number used in the remainder term of Taylor's theorem that falls between the limits
*a*and*b* - A number used in error approximations for formulas that are applications of Taylor's theorem, such as Newton-Cotes formulas

- In fluid dynamics, the Iribarren parameter.
- The initial mass function in astronomy.
- The correlation function in astronomy.
- Spatial frequency;
^{[3]}also sometimes temporal frequency. - A small displacement in MHD plasma stability theory
- The x-coordinate of computational space as used in computational fluid dynamics
- Potential difference in physics (in volts)
- The radial integral in the spin-orbit matrix operator in atomic physics.
- The Killing vector in general relativity.
- Average logarithmic energy decrement per collision (neutron calculations in nuclear physics)
- Pippard's cohesion length in superconductors
- The diameter of a crystal nucleus in nucleation theory
- Microturbulence velocity in a stellar atmosphere
- The dimensionless longitudinal momentum loss of a beam particle after a two-body interaction in accelerator physics.
- Dimensionless distance variable used in the Lane-Emden equation

- Propositional variables in some philosophical works, first found in Wittgenstein's Tractatus
- Extent of reaction, a concept in physical chemistry
^{[4]}used often in chemical engineering kinetics and thermochemistry - Unknown stereochemistry or stereocentre configuration in a planar ring system in organic chemistry,
^{[5]}as well as uppercase Xi for unknown*R*/*S*/*E*/*Z*configuration in general^{[6]} - Damping Ratio C/Ccr(vibrational analysis)
- One of the two different polypeptide chains of the human embryonic hemoglobin types Hb-Portland (?
_{2}?_{2}) and Hb-Gower I (?_{2}?_{2}) - A parameter denoted as warped time used to derive the equations for homogeneous azeotropic distillation
- State Price Density in mathematical finance
- The information vector in the Information Filter, GraphSLAM, and a number of other algorithms used for robot localization and robotic mapping.
- Used in Support Vector machines in cases where the data is not linearly separable.

- Greek Xi / Coptic Ksi

Preview | Ξ | ξ | Ⲝ | ⲝ | ||||
---|---|---|---|---|---|---|---|---|

Unicode name |
GREEK CAPITAL LETTER XI | GREEK LOWERCASE LETTER XI | COPTIC CAPITAL LETTER KSI | COPTIC LOWERCASE LETTER KSI | ||||

Encodings | decimal | hex | decimal | hex | decimal | hex | decimal | hex |

Unicode | 926 | U+039E | 958 | U+03BE | 11420 | U+2C9C | 11421 | U+2C9D |

UTF-8 | 206 158 | CE 9E | 206 190 | CE BE | 226 178 156 | E2 B2 9C | 226 178 157 | E2 B2 9D |

Numeric character reference | Ξ |
Ξ |
ξ |
ξ |
Ⲝ |
Ⲝ |
ⲝ |
ⲝ |

Named character reference | Ξ | ξ | ||||||

DOS Greek | 141 | 8D | 165 | A5 | ||||

DOS Greek-2 | 189 | BD | 232 | E8 | ||||

Windows 1253 | 206 | CE | 238 | EE | ||||

TeX | \Xi | \xi |

^{[7]}

- Mathematical Xi

Preview | 𝚵 | 𝛏 | 𝛯 | 𝜉 | 𝜩 | 𝝃 | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|

Unicode name |
MATHEMATICAL BOLD CAPITAL XI |
MATHEMATICAL BOLD LOWERCASE XI |
MATHEMATICAL ITALIC CAPITAL XI |
MATHEMATICAL ITALIC LOWERCASE XI |
MATHEMATICAL BOLD ITALIC CAPITAL XI |
MATHEMATICAL BOLD ITALIC LOWERCASE XI | ||||||

Encodings | decimal | hex | decimal | hex | decimal | hex | decimal | hex | decimal | hex | decimal | hex |

Unicode | 120501 | U+1D6B5 | 120527 | U+1D6CF | 120559 | U+1D6EF | 120585 | U+1D709 | 120617 | U+1D729 | 120643 | U+1D743 |

UTF-8 | 240 157 154 181 | F0 9D 9A B5 | 240 157 155 143 | F0 9D 9B 8F | 240 157 155 175 | F0 9D 9B AF | 240 157 156 137 | F0 9D 9C 89 | 240 157 156 169 | F0 9D 9C A9 | 240 157 157 131 | F0 9D 9D 83 |

UTF-16 | 55349 57013 | D835 DEB5 | 55349 57039 | D835 DECF | 55349 57071 | D835 DEEF | 55349 57097 | D835 DF09 | 55349 57129 | D835 DF29 | 55349 57155 | D835 DF43 |

Numeric character reference | 𝚵 |
𝚵 |
𝛏 |
𝛏 |
𝛯 |
𝛯 |
𝜉 |
𝜉 |
𝜩 |
𝜩 |
𝝃 |
𝝃 |

Preview | 𝝣 | 𝝽 | 𝞝 | 𝞷 | ||||
---|---|---|---|---|---|---|---|---|

Unicode name |
MATHEMATICAL SANS-SERIF BOLD CAPITAL XI |
MATHEMATICAL SANS-SERIF BOLD LOWERCASE XI |
MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL XI |
MATHEMATICAL SANS-SERIF BOLD ITALIC LOWERCASE XI | ||||

Encodings | decimal | hex | decimal | hex | decimal | hex | decimal | hex |

Unicode | 120675 | U+1D763 | 120701 | U+1D77D | 120733 | U+1D79D | 120759 | U+1D7B7 |

UTF-8 | 240 157 157 163 | F0 9D 9D A3 | 240 157 157 189 | F0 9D 9D BD | 240 157 158 157 | F0 9D 9E 9D | 240 157 158 183 | F0 9D 9E B7 |

UTF-16 | 55349 57187 | D835 DF63 | 55349 57213 | D835 DF7D | 55349 57245 | D835 DF9D | 55349 57271 | D835 DFB7 |

Numeric character reference | 𝝣 |
𝝣 |
𝝽 |
𝝽 |
𝞝 |
𝞝 |
𝞷 |
𝞷 |

These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.

*Media related to Xi (letter) at Wikimedia Commons*

Uppercase ? is used as an 'E' to stylise company names/logos like Razer (styled as **R?Z?R**), musician Banners (styled as **BANN?RS**), and in South Korean Boygroup ZE:A newest logo (styled as "Z?A") (Compare: Heavy Metal umlaut; Faux Cyrillic)

**^**Sometimes or .

"xi".*Merriam-Webster Dictionary*.

"xi".*Dictionary.com Unabridged*. Random House.**^**"xi". New Oxford American Dictionary, 2nd Edition.**^**SPIE Optipedia article: "Spatial Frequency"**^**IUPAC Gold Book Entry: "Extent of Reaction" Archived June 29, 2012, at the Wayback Machine**^**John Buckingham; Caroline M. Cooper; Rupert Purchase (18 November 2015).*Natural Products Desk Reference*. CRC Press. pp. 53-. ISBN 978-1-4398-7362-5.**^***Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names*. 2014. pp. 1159-1160. ISBN 9780854041824. Retrieved 2017.**^**Unicode Code Charts: Greek and Coptic (Range: 0370-03FF)

This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.

Popular Products

Music Scenes

Popular Artists