Delta (letter)
From Wikipedia, the free encyclopedia
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| 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 |
| Obsolete letters | |
 Digamma |
 Qoppa |
 San |
 Sampi |
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| Greek diacritics | |
Delta (uppercase Δ, lowercase δ; Greek: Δέλτα [ðelta] Thelta) 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 arose from Delta include the Latin D and the equivalent in the Cyrillic alphabet: Д.
In Modern Greek it represents a voiced dental fricative /ð/, (like the th in the English word this) but in the Ancient Greek language, it represented a voiced dental plosive /d̪/.
A river delta is so named because its shape approximates the upper-case letter delta.
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[edit] The upper-case letter Δ
The upper-case letter Δ can be used to denote:
- Change; e.g. in:
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= the average change of y per unit x, i.e. the change of y over the change of x
- More specifically, the difference operator.
- 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
- 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 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
- In genetics, it can stand for a gene deletion, e.g. the CCR5-Δ32 a deletion of the CCR5 at the 32nd bp segment
- In chemistry, it denotes the change in a physical property such as heat, e.g ΔTemp would stand for the change in Temp
[edit] The lower-case letter δ
The lower-case letter δ can be used to denote:
- An infinitesimal change in the value of a variable in mathematics or science
- 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[1]
