# Lambda

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Not to be confused with Lambada.
"Labda" redirects here. For the mythological figure, see Labda (mythology). For other uses, see Lambda (disambiguation).
"Λ" redirects here. It is not to be confused with turned V.

Lambda (uppercase Λ, lowercase λ; Greek: Λάμ(β)δα lam(b)da) is the 11th letter of the Greek alphabet. In the system of Greek numerals lambda has a value of 30. Lambda is related to the Phoenician letter Lamed . Letters in other alphabets that stemmed from lambda include the Latin L and the Cyrillic letter El (Л, л). The ancient grammarians and dramatists give evidence to the pronunciation as [laːbdaː] (λάβδα) in Classical Greek times.[1] In Modern Greek the name of the letter, Λάμδα, is pronounced [lamða]; the spoken letter itself has the sound of [l] as with Latinate "L".

In early Greek alphabets, the shape and orientation of lambda varied.[2] Most variants consisted of two straight strokes, one longer than the other, connected at their ends. The angle might be in the upper-left, lower-left ("Western" alphabets), or top ("Eastern" alphabets). Other variants had a vertical line with a horizontal or sloped stroke running to the right. With the general adoption of the Ionic alphabet, Greek settled on an angle at the top; the Romans put the angle at the lower-left.

The HTML 4 character entity references for the Greek capital and small letter lambda are "&#923;" and "&#955;", respectively.[3] The Unicode number for lambda is 03BB.

The Greek alphabet on a black figure vessel, with a Phoenician-lamed-shaped lambda. (The gamma has the shape of modern lambda.)

## Symbol

### Lower-case letter λ

Lower-case lambda

## Lambda as a programming construct

 >>> list = ['woman', 'man', 'horse', 'boat', 'plane', 'dog'] >>> sorted(list, key = lambda word: (word[-1])) ['horse', 'plane', 'dog', 'woman', 'man', 'boat']
• In the C# programming language a lambda expression is an anonymous function that can contain expressions and statements.[6]
• The language Unlambda is a functional programming language based upon combinatory logic, a simplification of the lambda calculus that does not involve the lambda at all, hence the un- prefix.
• An automotive oxygen sensor (O2 sensor) is also known as a lambda probe, sensor, sond, or sonde.
• Lambda is used in art and photography to refer to a digital Type C print, or to the equipment that is used to produce it.
• Lambda was used by Pythagoras to denote the "Lambda number sequence" 1, 2, 3, 4, 9, 8, 27, ...,(sequence A098293 in OEIS) formed by the integers of the form 2i and 3i, for nonnegative integer i.[citation needed]
• In the study of gasoline engines, Lambda sometimes refers to the air/fuel mixture going into the engine.

## Lambda as a name

• Stargate SG-1 uses a modified upper-case lambda, with a small circle above the apex, to indicate Earth. This symbol has since become associated with the entire franchise.[7][8]
• The popular science fiction universe of Star Wars uses a transport vehicle known as the Lambda-class shuttle that when viewed forward has the shape of the lowercase lambda.[9]
• Lambda is occasionally used in graphic design to represent a stylised 'A'. Examples include the Disney movie Atlantis: The Lost Empire, the logo of the band Angels & Airwaves, the logo of the band Dream Theater, the logo of electronics company Samsung, and the logo of the engineering consultancy Atkins. Conversely, the name of the band Λucifer (pronounced lucifer) is sometimes spelled Aucifer.
• The upper-case lambda is used as the alias of Providence, Rhode Island based musician Xavier Valentine.[10]
• The Half-Life franchise of video games uses an encircled block style lower-case lambda as the franchise logo (Half-Life 2 adds the numeral 2 into the logo as superscript), prominently featured on the chest of Gordon Freeman's (the protagonist) powered armor, known as an HEV suit. In the first game, the logo appears at the entrances of the Black Mesa Research Facility's Lambda Complex, which conducted teleportation research. In Half-Life 2 and its Episodes, the encircled block lambda is the universal symbol of the Resistance, often spraypainted to mark the location of safehouses and hidden supply caches; full-time Resistance members wear armbands containing a lower-case lambda without the circle.
• In the 2D fighting game series BlazBlue, a recurring character named Lambda-11 appears in the various games' story modes and as a playable character.
• Several gay rights organizations, such as Lambda Legal and the Lambda Literary Award derive their names from the use of a lower-case lambda as a symbol for gay and lesbian rights.
• In the RPG game Tales of Graces, originally made for the Wii, Lambda is the name of the main story's antagonist.
• There is a PlayStation Vita game known as Cytus Lambda.

## Character Encodings

Unicode uses the spelling "lamda" in character names, instead of "lambda".

• Greek Lambda / Coptic Laula
CharacterΛλ
Unicode nameGREEK CAPITAL LETTER LAMDAGREEK SMALL LETTER LAMDAGREEK LETTER SMALL CAPITAL LAMDACOPTIC CAPITAL LETTER LAULACOPTIC SMALL LETTER LAULA
Encodingsdecimalhexdecimalhexdecimalhexdecimalhexdecimalhex
Unicode923U+039B955U+03BB7463U+1D2711414U+2C9611415U+2C97
UTF-8206 155CE 9B206 187CE BB225 180 167E1 B4 A7226 178 150E2 B2 96226 178 151E2 B2 97
Numeric character reference&#923;&#x39B;&#955;&#x3BB;&#7463;&#x1D27;&#11414;&#x2C96;&#11415;&#x2C97;
Named character reference&Lambda;&lambda;
DOS Greek1388A162A2
DOS Greek-2182B6229E5
Windows 1253203CB235EB
TeX\Lambda\lambda
• Mathematical Lambda
Character𝚲𝛌𝛬𝜆𝜦𝝀
Unicode nameMATHEMATICAL BOLD
CAPITAL LAMDA
MATHEMATICAL BOLD
SMALL LAMDA
MATHEMATICAL ITALIC
CAPITAL LAMDA
MATHEMATICAL ITALIC
SMALL LAMDA
MATHEMATICAL BOLD ITALIC
CAPITAL LAMDA
MATHEMATICAL BOLD ITALIC
SMALL LAMDA
Encodingsdecimalhexdecimalhexdecimalhexdecimalhexdecimalhexdecimalhex
Unicode120498U+1D6B2120524U+1D6CC120556U+1D6EC120582U+1D706120614U+1D726120640U+1D740
UTF-8240 157 154 178F0 9D 9A B2240 157 155 140F0 9D 9B 8C240 157 155 172F0 9D 9B AC240 157 156 134F0 9D 9C 86240 157 156 166F0 9D 9C A6240 157 157 128F0 9D 9D 80
UTF-1655349 57010D835 DEB255349 57036D835 DECC55349 57068D835 DEEC55349 57094D835 DF0655349 57126D835 DF2655349 57152D835 DF40
Numeric character reference&#120498;&#x1D6B2;&#120524;&#x1D6CC;&#120556;&#x1D6EC;&#120582;&#x1D706;&#120614;&#x1D726;&#120640;&#x1D740;
Character𝝠𝝺𝞚𝞴
Unicode nameMATHEMATICAL SANS-SERIF
BOLD CAPITAL LAMDA
MATHEMATICAL SANS-SERIF
BOLD SMALL LAMDA
MATHEMATICAL SANS-SERIF
BOLD ITALIC CAPITAL LAMDA
MATHEMATICAL SANS-SERIF
BOLD ITALIC SMALL LAMDA
Encodingsdecimalhexdecimalhexdecimalhexdecimalhex
Unicode120672U+1D760120698U+1D77A120730U+1D79A120756U+1D7B4
UTF-8240 157 157 160F0 9D 9D A0240 157 157 186F0 9D 9D BA240 157 158 154F0 9D 9E 9A240 157 158 180F0 9D 9E B4
UTF-1655349 57184D835 DF6055349 57210D835 DF7A55349 57242D835 DF9A55349 57268D835 DFB4
Numeric character reference&#120672;&#x1D760;&#120698;&#x1D77A;&#120730;&#x1D79A;&#120756;&#x1D7B4;

These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.

## References

1. ^ Herbert Weir Smyth. A Greek Grammar for Colleges. I.1.c
2. ^ "Epigraphic Sources for Early Greek Writing". Poinikastas.csad.ox.ac.uk. Retrieved 2011-10-03.
3. ^ World Wide Web Consortium W3C. HTML 4.01 Specification, 24. Character entity references in HTML 4. [1]
4. ^ "Encyclopedia Astronautica: Lambda". www.astronautix.com. Retrieved 2012-12-18.
5. ^ Wankat Separation Process Engineering 2nd ed, Prentice Hall
6. ^ "Lambda Expressions (C# Programming Guide)". Msdn.microsoft.com. Retrieved 2011-10-03.
7. ^ Read, David (July 15, 2010). "Earth Symbol". Propworx. Retrieved 2010-10-12.
8. ^ "Official Stargate Website". Metro-Goldwyn-Mayer. Retrieved 2010-10-13.
9. ^ "Imperial Lambda-class shuttle". Star Wars Databank. Lucasfilm. Retrieved 2010-10-12.
10. ^ "Ʌ". Aarrcc.bandcamp.com. Retrieved 2011-10-03.