Epsilon

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Look up Ε, ε 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 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

Epsilon (uppercase Ε, lowercase ε) is the fifth letter of the Greek alphabet. In the system of Greek numerals it has a value of 5. It was derived from the Phoenician letter He . Letters that arose from Epsilon include the Roman E and Cyrillic Ye.

"Epsilon" ("simple e") was coined to distinguish the letter from αι, which by the medieval period was pronounced the same way.

A variation is the lunate epsilon (ϵ), which has its origins in Medieval Greek. The lunate epsilon is often used interchangeably with the "normal" epsilon in many circumstances. (The lunate epsilon ϵ is not to be confused with the set symbol ∈)

[edit] Symbol

The upper-case Epsilon is not a commonly-used symbol outside of the Greek language because of its similarity to the Roman letter E.

The lower-case letter ε is used as the symbol for:

In mathematics (particularly calculus), a small positive quantity, usually denoted ε; see limit.
- By analogy with this, the late mathematician Paul Erdős also used the term "epsilons" to refer to children (Hoffman 1998, p. 4).
In set theory, the limit ordinal of the sequence <math>\omega,\omega^{\omega},\omega^{\omega^{\omega}},\dots</math>.
In computing, the precision of a numeric data type.
In computer science, the empty string, though different writers use a variety of other symbols for the empty string as well, including the lower case Greek letter lambda.
In mathematics, the Levi-Civita symbol.
In mathematics, set membership (often written ∈ instead of ε).
In mathematics, to represent the dual numbers: a + bε, with ε²=0 and ε≠0.
In physics, the permittivity of a medium.
In physics/electronics, the EMF of a circuit
In automata theory, a transition that involves no shifting of an input symbol.
In astronomy, the fifth brightest (usually) star in a constellation. See Bayer designation.
In the International Phonetic Alphabet, the open-mid front unrounded vowel, (but generally written ɛ instead of ε) as in the English word "pet" (/pɛt/)
In physics, the strain of a material (A ratio of extensions).
GM Epsilon platform, a mid-size car automobile platform from General Motors.
In astronomy, Epsilon is the name for Uranus' most distant and most visible ring.

[edit] Fictional names

Epsilon in Malaysian Pale is the name of the second solo album released by Tangerine Dream leader Edgar Froese in 1975.
Epsilon is also an Australian light-powered female-looking robot that fought Pluto in an episode of Astro Boy.
Epsilon is the primordial guide of Jess in the children's novel The Riddles of Epsilon by Christine Morton-Shaw.
Epsilon Eridani III is the planet that the spacestation Babylon 5 orbited in the eponymous sci-fi television series.
E-104 Epsilon is also the name of a robot in Sonic Adventure.
Epsilon Semi-Moron is the lowest and least intelligent caste in Aldous Huxley's dystopic satire Brave New World.
Epsilon is the name of an unlockable creature in the game Monster Rancher 2
In Greek it is used for Epsilon Team.
"Epsilon Mirror" is the name of one of Aika's moves in the video game Skies of Arcadia.
Epsilon is the leader of the Rebellion in Mega Man X: Command Mission
"The Epsilon Program" is a mysterious cult in the video game Grand Theft Auto: San Andreas by Game Developer Rockstar North. This cult is thought to be based on the Scientology cult.
The Epsilon Project is a fictional experiment mentioned in the Dreamcast and Xbox versions of Dead or Alive 2 and is based around cloning.