Sigma

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For other uses, see Sigma (disambiguation).

Look up Σ, σ, ς in Wiktionary, the free dictionary.

Greek alphabet

Α α Alpha	Ν ν Nu
Β β Beta	Ξ ξ Xi
Γ γ Gamma	Ο ο Omicron
Δ δ Delta	Π π ϖ Pi
Ε ε Epsilon	Ρ ρ Rho
Ζ ζ Zeta	Σ σ ς Sigma
Η η Eta	Τ τ Tau
Θ θ Theta	Υ υ Upsilon
Ι ι Iota	Φ φ Phi
Κ κ Kappa	Χ χ Chi
Λ λ Lambda	Ψ ψ Psi
Μ μ Mu	Ω ω Omega
Obsolete letters
Ϝ ϝ Digamma	Ϻ ϻ San
Ϙ ϙ Qoppa	Ϡ ϡ Sampi
Ϛ ϛ Stigma	Ϸ ϸ Sho
diacritics

The Madaba Map, a sixth-century mosaic map of Jerusalem ("ΗΑΓΙΑ ПОΛΙΣ") uses the lunate sigma.

Sigma (upper case Σ, lower case σ, lower case in word-final position ς) is the eightteenth letter of the Greek alphabet. In the system of Greek numerals it has a value of 200. When used at the end of a word, and the word is not upper case, the final form (ς) is used.

The letter is ultimately derived from Phoenician Sin . However, its name derives from Samekh.

In Eastern forms of Greek writing (as opposed to the Western Greek alphabet used in the European Greek colonies) and in the Middle Ages, the lunate sigma (upper case Ϲ, lower case ϲ) — which resembles, but which is not at all related to, the Latin letter C — was often used. Lunate sigma was frequently used for writing Medieval Greek, and it can still sometimes be seen in inscriptions in Greek Orthodox churches, but also in certain printed editions of classical authors. The form of the Cyrillic letter С [s] and Coptic letter sima are derived from lunate sigma.

On coins from the Hellenistic period in India, the script of later coins sometimes use lunate signa. This was possibly due to Latin influence.

A dotted lunate sigma (sigma periestigmenon, encoded at U+03FE Ͼ) is used by Aristarchus of Samothrace as an editorial sign indicating that the line so marked is at an incorrect position. Similarly, an antisigma (encoded at U+03FD Ͻ) may mark a line that is out of place. A dotted antisigma (antisigma periestigmenon, encoded at U+03FF Ͽ) may indicate a line after which rearrangements should be made, or to variant readings of uncertain priority.

The uppercase form of sigma was borrowed into the Latin alphabet to serve as the uppercase of esh (lowercase: ʃ).

1 Science
2 Politics
3 Popular culture and use in fiction
4 Hi-Fi Headphones
5 See also

[edit] Science

Upper case Σ is used as a symbol for:

the summation operator
a class of baryons in particle physics

Lower case σ is used for:

sigma bonds in chemistry
the parametric standard deviation of a population (as opposed to a sample) in statistics
a quality model for business, Six Sigma, based on the standard deviation, often referred to as "6σ"
sigma-algebras, sigma-fields and sigma-finiteness in measure theory
the sum-of-divisors function in number theory
the Stefan-Boltzmann constant
the "sigma factor" of RNA polymerase
a measure of electrical conductivity
Normal stress in continuum mechanics
volatility of a stock generally needed for options pricing
a syllable in phonology

[edit] Politics

During the 1930s, an upper case Σ was in use as the symbol of the Ação Integralista Brasileira, a fascist party in Brazil.

[edit] Popular culture and use in fiction

In a practice similar to faux Cyrillic, capital sigmas are sometimes used in place of Roman E to give a Greek flavour to titles or text (for example, the film My Big Fat GRΣΣK Wedding).

Sigma is the name of the main villain in Capcom's Mega Man X. His symbol is an upper-case sigma formed into an wolf's face.

Sigma Octanus IV is a fictional planet in the Halo books.

Sigma is the name of third server in the series of .hack//IMOQ (PS2 video games)

Sigma is a measure of male sexual arousal coined by the character Lawrence Waterhouse in Neal Stephenson's Cryptonomicon

Sigma is the name for the new, upcoming Ninja Gaiden game from Team Ninja.

In the television series Doctor Who, Theta Sigma is the nickname of the Doctor.
The current GI Joe incarnation is entitled G.I. Joe: Sigma 6.
Sigma is the name of a song from Japanese singer Shiina Ringo.
Sigma is the title of a 2007 album by eufonius.
The Sigma Protocol is a 2002 book by Robert Ludlum.

Sigma Shipyards is the name of a corporation in the Escape Velocity Nova computer game.

Vector Sigma is the Computer matrix that created the cybertronian lifeforms the Transformers in the popular cartoon series from the 1980's

Sigma is used in the latter (Chris Redfield) half of survival-horror game Resident Evil Code: Veronica in which you much retrieve 'Clement a ' and 'Clement Σ'
Sigma 2,3,5,6,7,8,9 Computers produced by Xerox Data Systems in the 1970's following purchase of SDS, Scientific Data Systems by them. Successful range of Scientific Computers similar to IBM 370's.