Sigma

The title of this article is ambiguous. Further meanings are listed under Sigma (disambiguation) .

Sigma
pronunciation
antique	[ s, z ] ​​
modern	[ s ] ​​
Equivalents
Latin	Ss
Cyrillic	Сс
Hebrew	ס
Arabic	ﺱ
Phoenician	?
transcription
From the ancient world	s
From the modern	s
Coding Capitals Unicode number U + 03A3 Unicode name GREEK CAPITAL LETTER SIGMA HTML & # 931; HTML entity ? Minuscule Unicode number U + 03C3 Unicode name GREEK SMALL LETTER SIGMA HTML & # 963; HTML entity & sigma; Variation 1 Unicode number U + 03C2 Unicode name GREEK SMALL LETTER FINAL SIGMA HTML & # 962; HTML entity & sigmaf; 1 at the end of the word

The Greek letter Sigma ( Greek neuter Σίγμα , majuscule Min , minuscule in the word σ , minuscule at the end of the word ς ) is the 18th  letter of the Greek alphabet and, according to the Milesian system, has the numerical value 200. In the Greek language it is called the voiceless “ S " spoken.

Origin and derivatives

The Phoenician alphabet had four letters for sibilants . The Greeks adopted two of them for their S-sound, but they never appeared at the same time in one of the different ancient Greek alphabets. The letter Samech was used in the Ionic alphabet as X with the sound value ksi . His name, however, was transferred in a slightly modified form to the Phoenician letter "Sin", which was now called Sigma in Greek.

In Hellenistic times , the letter in manuscripts to today as was lunares Sigma (lunar " crescent-shaped ") simplified form designated (originally only as Majuskel Σ for Unziale , from the minuscule ς ), which in late antiquity and the Byzantine Empire to most used form and is still common today in the ecclesiastical context ( Orthodox churches ). Both the Coptic semma ( Ⲥ / ⲥ ) and the Cyrillic Es ( С / с ) are derived from this letter form , while the Latin S is derived from the common capitals via the Etruscan form .

use

• as a small sigma σ
  • in quality management Six Sigma (3.4 errors per million possible errors)
  • in physics
    • for surface tension
    • for the yield stress
    • for the surface electrical charge density
    • for the Stefan-Boltzmann constant
    • for the specific electrical conductivity of a material
    • for the Pauli matrices
    • for the cross section
    • for mechanical tension
  • in materials science
    • a very brittle phase in the Fe-Cr system
    • the tension
  • in computer science
    • to denote the selection in relational algebra
    • to designate the selectivity of a database query
  • in math
    • in the statistics for the standard deviation of the population
    • in mathematical number theory for a partial sum
    • in functional analysis for the spectrum of a linear operator
    • in measure theory that a property or axiom extends from finite to countable index sets .
    • for number walls as a designation for the number of basic cells
  • in chemistry
    • for naming a molecular orbital bond
    • to name the sigma complex
    • as a sign of the volume concentration
  • in biology
    • for a protein which is necessary for the initiation of transcription by binding to the RNA polymerase (see sigma factor )
  • in phonology
    • for one syllable
  • in microeconomics
    • as a sign of the elasticity of substitution
  • in structural geology
    • to name a clast type (see Sigma-Klast )

• as a capital sigma Σ
  • Identifier in physics for a Σ-baryon .
  • Symbol in physics for a frame of reference .
  • Symbol in mathematics for sum or signature .
  • Symbol in statistics for the covariance matrix
  • Symbol in theoretical computer science for an alphabet
  • In astronomy , the sigma is the speed at which the stars move at the very edge of a galaxy .

• as a word sigma
  • Use in ecology and vegetation: sigma sociology (synsociology), d. H. the recording of vegetation complexes
  • Abbreviation in medicine for the S-shaped part of the large intestine ( Colon sigmoideum ).

Examples

• Socrates ( Σωκράτης , ancient Greek pronunciation Sōkrátēs , today's Greek Sokrátis )
• Lunar Sigma:

• 

  Mosaic of the Three Graces

• 

  Detail of the Nomos inscription on the back of the monumental statues , Nemrut Dağı

• 

  Entrance to the Greek Orthodox monastery Μετοχιον Γεθσημανης Metochion Gethsimanis , Church of the Holy Sepulcher in Jerusalem

• 

  Apse painting Jesus Christ as Pantocrator with the letters "IC" and "XC" for Jesus Christ, Beuron Art School , St. Remigius (Bliesen)

Unicode output of the variants

In addition to the normal form specified in the above info block , the lunar sigma is also coded as a symbol in the Unicode block Greek and Coptic :

• Majuskel Σ (Unicode U + 03F9: "GREEK CAPITAL lunate SIGMA SYMBOL")
• Minuscule ϲ (Unicode U + 03F2: "GREEK LUNATE SIGMA SYMBOL")

There is also a dotted version of this:

• Majuskel Ͼ (Unicode U + 03Fe: "GREEK CAPITAL DOTTED lunate SIGMA SYMBOL")
• Minuscule ͼ (Unicode U + 037C: "GREEK SMALL DOTTED LUNATE SIGMA SYMBOL")

In addition , the antisigma developed by the Roman emperor Claudius as part of his writing reform is also defined, as is a dotted version of it:

• Majuskel Ͻ (Unicode U + 03FD "GREEK CAPITAL REVERSED lunate SIGMA SYMBOL")
• Minuscule ͻ (Unicode U + 037B: "GREEK SMALL REVERSED LUNATE SIGMA SYMBOL")
• Majuskel Ͽ (Unicode U + 03FF "GREEK CAPITAL REVERSED DOTTED lunate SIGMA SYMBOL")
• Minuscule ͽ (Unicode U + 037D: "GREEK SMALL REVERSED DOTTED LUNATE SIGMA SYMBOL")

Web links

Commons : Sigma  collection of images

Wiktionary: Sigma  - explanations of meanings, word origins, synonyms, translations