 Delta (letter)

Greek alphabet Αα Alpha Νν Nu Ββ Beta Ξξ Xi Γγ Gamma Οο Omicron Δδ Delta Ππ Pi Εε Epsilon Ρρ Rho Ζζ Zeta Σσς Sigma Ηη Eta Ττ Tau Θθ Theta Υυ Upsilon Ιι Iota Φφ Phi Κκ Kappa Χχ Chi Λλ Lambda Ψψ Psi Μμ Mu Ωω Omega History Archaic local variants
· · · · ·Ligatures (ϛ, ȣ, ϗ) · Diacritics Numerals: (6) · (90) · (900) In other languages Bactrian · Coptic · Albanian Scientific symbols
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Delta (uppercase Δ, lowercase δ; δέλτα; Modern Greek [ˈðelta] dhélta) is the fourth letter of the Greek alphabet. In the system of Greek numerals it has a value of 4. It was derived from the Phoenician letter Dalet. Letters that come from delta include Latin D and Cyrillic Д.
A river delta (originally, the Nile River delta) is so named because its shape approximates the uppercase letter delta (the shape is a triangle).
Contents
Pronunciation
In Ancient Greek, it represented a voiced dental plosive /d/. In Modern Greek, it represents a voiced dental fricative /ð/, like the "th" in "that" or "this". It is romanized as d or dh.
Mathematics and the Sciences
Upper case
The uppercase letter Δ can be used to denote
 Change of any variable quantity, in mathematics and the sciences; for example, in

 , the average change of y per unit x, i.e. the change of y over the change of x
 More specifically, the difference operator.^{[1]}
 The Laplace operator:
 The discriminant of a polynomial equation, especially the quadratic equation:
 A macroscopic change in the value of a variable in mathematics or science
 Uncertainty in a physical variable as seen in for instance the uncertainty principle
 An interval of possible values for a given quantity for instance across a sample^{[citation needed]}
 Any of the delta particles in particle physics
 The determinant of the matrix of coefficients of a set of linear equations (see Cramer's Rule)
 That an associated locant number represents the location of a covalent bond in an organic compound, the position of which is variant between isomeric forms
 In chemistry, it is often used to represent the addition of heat in a reaction.
 In legal shorthand, it represents a defendant
 In the financial markets, it is one of the Greeks that describes the rate of change of an option price for a given change in the underlying benchmark
 It is the symbol of the Greek inventor and architect Daedalus
 In genetics, it can stand for a gene deletion, e.g. the CCR5Δ32 a deletion of the CCR5 at the 32nd base pair segment
 The American Dental Association cites it (together with omicron for "odont") as the symbol of dentistry.^{[2]}
Lower case
The lowercase letter δ can be used to denote
 An infinitesimal change in the value of a variable in infinitesimal calculus
 An auxiliary function in Calculus used to rigorously define the limit or continuity of a given function.
 The Kronecker delta in mathematics
 The Dirac delta function in mathematics
 The transition function in automata
 Deflection in engineering mechanics
 The Force of Interest in actuarial science
 The chemical shift of Nuclear Magnetic Resonance in chemistry
 The relative electronegativity of different atoms in a molecule, δ^{−} being more electronegative than δ^{+}
 Text requiring deletion in proofreading. The usage is said to date back to classical times
 In some of the manuscripts written by Dr. John Dee, the character of delta is used to represent Dee
 The Computer Science chapter at the Royal Institute of Technology^{[3]}
 Is a subunit of the F1 sector of the FATPase
 The declination of an object in the equatorial coordinate system of astronomy
 The dividend yield on the BlackScholes option pricing formula
 Signifies a major seventh chord in jazz music notation.
 Ratios of environmental isotopes, such as ^{18}O/^{16}O and D/^{1}H from waters are displayed using delta notation  δ^{18}O and δD, respectively
 The rate of depreciation of the aggregate capital stock of an economy in an exogenous growth model in macroeconomics.^{[4]}
Meteorology
 The name Delta was used as a name during the 1972 Atlantic hurricane season and the 2005 Atlantic hurricane season as Tropical Storm Delta (2005).
See also
 D, d
 Д, д
 Th (digraph)
 Greek letters used in mathematics, science, and engineering
 Nabla symbol ()
 ∂  the partial derivative symbol, sometimes mistaken for a lowercase Greek letter Delta.
 ẟ  Latin delta
References
 ^ http://ocw.mit.edu/highschool/courses/highlightsofcalculus/bigpictureofcalculus/
 ^ ADA.org: Oral Health Topics: Emblem/Insignia of Dentistry^{[dead link]}
 ^ "Konglig Datasektionen, Statutes, §2.2 Symbol". D.kth.se. http://www.d.kth.se/sektionen/formalia/stadgar/#paragraf2.2. Retrieved 20100907.
 ^ [1]^{[dead link]}
Categories: Greek letters
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