Mu

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'''Mu''' (uppercase '''Μ''', lowercase '''μ'''; [[Ancient Greek]] {{polytonic|μῦ}} {{IPA-el|mŷː|}}), [[Modern Greek]] μι or μυ {{IPA-el|mi|}}) is the 12th letter of the [[Greek alphabet]]. In the system of [[Greek numerals]] it has a value of 40. Mu was derived from the [[Egyptian hieroglyph]]ic symbol for water (𓈖) which had been simplified by the [[Phoenicia]]ns and named after their word for water, to become [[Mem|𐤌]]. Letters that arose from mu include the Roman [[M]] and the Cyrillic letter [[Em (Cyrillic)|М]].
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==Names==
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===Ancient Greek===
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In [[Ancient Greek]], the name of the letter is written {{polytonic|μῦ}} and pronounced {{IPA-el|mŷː|}}.
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===Modern Greek===
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In [[Modern Greek]], the name of the letter is spelled μι and pronounced {{IPA-el|mi|}}. In monotonic orthography, the ancient version is written with an [[acute accent]] instead of a [[circumflex]]: μύ.
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==Symbol==
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The lower-case letter mu (μ) is used as a special symbol in many [[academic field]]s. The upper case mu is not used, since it is normally identical to Latin [[M]].
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===Mathematics===
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In [[mathematics]]:
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*the µ-roots of a [[complex number]] ''z = a + bi''
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*the [[Möbius function]] in [[number theory]]
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*the [[integrating factor]] in [[ordinary differential equations]]
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*the population [[mean]] or [[expected value]] in [[probability]] and [[statistics]]
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*a [[measure (mathematics)|measure]] in [[measure theory]]
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*[[Mu operator|minimalization]] in [[Computability theory (computer science)|computability theory]] and [[Recursion theory]]
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*the learning rate as used in [[artificial neural networks]]
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===Measurement===
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In measurement:
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*the [[SI prefix]] ''[[micro-]]'', which represents one millionth, or 10<sup>&minus;6</sup>.
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*the micron, an old unit which corresponds to the [[micrometre]] (which is now denoted "µm")
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===Physics and engineering===
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In [[classical physics]] and [[engineering]]:
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*the [[friction#Coefficient of friction|coefficient of friction]] (also used in aviation as braking coefficient)
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*[[reduced mass]] in the [[two-body problem]]
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*[[linear density]] or mass per unit length in strings and other one-dimensional objects.
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*[[permeability (electromagnetism)|permeability]] in [[electromagnetism]]
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*the [[magnetic dipole moment]] of a current-carrying coil
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*[[Viscosity#Viscosity .28dynamic viscosity.29: .CE.BC|dynamic viscosity]] in [[fluid mechanics]]
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*the [[Amplifier|amplification]] factor of a [[triode]] [[vacuum tube]]
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*the [[electrical mobility]] of a charged particle
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*the [[airspeed]] relative to rotor tip speed, in [[rotorcraft]]
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In [[particle physics]]:
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*the [[elementary particle]]s called the [[muon]] and antimuon
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In [[thermodynamics]]:
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*the [[chemical potential]] of a system or component of a system.
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===Chemistry===
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In [[chemistry]]:
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*the prefix given in [[IUPAC]] nomenclature for a [[bridging ligand]].
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===Pharmacology===
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In [[pharmacology]]:
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*an important [[opiate receptor]]
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===Orbital mechanics===
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In [[orbital mechanics]]:
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*[[Standard gravitational parameter]] of a [[celestial body]], the product of the [[gravitational constant]] ''G'' and the [[mass]] ''M''.
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*planetary discriminant, represents an experimental measure of the actual degree of [[Clearing the neighbourhood|cleanliness]] of the orbital zone, a [[wiktionary:criterion|criterion]] for [[IAU definition of planet|defining]] a [[planet]]. µ is calculated by dividing the mass of the candidate body by the total mass of the other objects that share its orbital zone.
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===Music===
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*[[Mu major chord]]
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===Software===
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In [[application software|application]] names:
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*[[μTorrent]], a [[BitTorrent]] client
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===Cameras===
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The [[Olympus Corporation]] manufactures a series of digital cameras called Olympus µ[mju:] or Olympus Stylus.<sup>[1]</sup>
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===Linguistics===
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In [[phonology]], it often stands for [[mora (linguistics)|mora]].
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==Computing==
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In Unicode, the upper and lower case mu are encoded at {{u+|039C}} and {{U+|03BC}} respectively. In [[ISO 8859-7]] they are encoded at CC<sub>[[hexadecimal|HEX]]</sub> and EC<sub>HEX</sub>. In HTML code, the μ character is represented by "&amp;#956;", "&amp;#x3BC;" and the entity "&amp;mu;".
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The [[Micro-|'''micro sign''']] or [[micron]] is considered a distinct [[Character (word)|character]] from the Greek alphabet letter by Unicode for historical reasons (although it is a [[homoglyph]]) and is found at U+00B5 as well as position B5<sub>HEX</sub> in [[ISO 8859]]-[[ISO-8859-1|1]], [[ISO-8859-3|3]], [[ISO-8859-8|8]], [[ISO-8859-9|9]], [[ISO-8859-13|13]] and [[ISO-8859-15|15]], and thus in the corresponding Windows code pages [[Windows-1252]] etc. In HTML code, the µ symbol is represented by "&amp;#181;", "&amp;#xB5;" and the [[HTML entity|entity]] "&amp;micro;". When Alt-0181 or the [[code page 437|DOS legacy]] Alt+230 is typed into an editable field using the [[numeric keypad]] in [[Microsoft Windows]], the µ symbol appears. Also pressing AltGr + M results in a µ on some keyboard layouts.
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Because µ is the abbreviation for the [[metric system]] prefix [[micro-]], the symbol is used in many word plays about the field of micro-computing. For example, the symbol is used in the name and logo of the popular [[bittorrent client]], [[µTorrent]]. Also, the microcontrollers are commonly represented in schematics as µC. It is sometimes simply substituted with a '''u''', the most similar-looking [[ASCII]] glyph, eg. ''uTorrent''.
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==References==
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1.^ Olympus History : [http://www.olympus-global.com/en/corc/history/camera/m_series.cfm%7Cµ(mju:) (Stylus) Series]
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[[Category:Greek letters]]

Revision as of 19:50, 15 March 2011

Mu (uppercase Μ, lowercase μ; Ancient Greek Template:IPA-el), Modern Greek μι or μυ Template:IPA-el) is the 12th letter of the Greek alphabet. In the system of Greek numerals it has a value of 40. Mu was derived from the Egyptian hieroglyphic symbol for water (𓈖) which had been simplified by the Phoenicians and named after their word for water, to become 𐤌. Letters that arose from mu include the Roman M and the Cyrillic letter М.

Contents

Names

Ancient Greek

In Ancient Greek, the name of the letter is written and pronounced Template:IPA-el.

Modern Greek

In Modern Greek, the name of the letter is spelled μι and pronounced Template:IPA-el. In monotonic orthography, the ancient version is written with an acute accent instead of a circumflex: μύ.

Symbol

The lower-case letter mu (μ) is used as a special symbol in many academic fields. The upper case mu is not used, since it is normally identical to Latin M.

Mathematics

In mathematics:

Measurement

In measurement:

  • the SI prefix micro-, which represents one millionth, or 10−6.
  • the micron, an old unit which corresponds to the micrometre (which is now denoted "µm")

Physics and engineering

In classical physics and engineering:

In particle physics:

In thermodynamics:

Chemistry

In chemistry:

Pharmacology

In pharmacology:

Orbital mechanics

In orbital mechanics:

Music

Software

In application names:

Cameras

The Olympus Corporation manufactures a series of digital cameras called Olympus µ[mju:] or Olympus Stylus.[1]

Linguistics

In phonology, it often stands for mora.

Computing

In Unicode, the upper and lower case mu are encoded at Template:U+ and Template:U+ respectively. In ISO 8859-7 they are encoded at CCHEX and ECHEX. In HTML code, the μ character is represented by "&#956;", "&#x3BC;" and the entity "&mu;".

The micro sign or micron is considered a distinct character from the Greek alphabet letter by Unicode for historical reasons (although it is a homoglyph) and is found at U+00B5 as well as position B5HEX in ISO 8859-1, 3, 8, 9, 13 and 15, and thus in the corresponding Windows code pages Windows-1252 etc. In HTML code, the µ symbol is represented by "&#181;", "&#xB5;" and the entity "&micro;". When Alt-0181 or the DOS legacy Alt+230 is typed into an editable field using the numeric keypad in Microsoft Windows, the µ symbol appears. Also pressing AltGr + M results in a µ on some keyboard layouts.

Because µ is the abbreviation for the metric system prefix micro-, the symbol is used in many word plays about the field of micro-computing. For example, the symbol is used in the name and logo of the popular bittorrent client, µTorrent. Also, the microcontrollers are commonly represented in schematics as µC. It is sometimes simply substituted with a u, the most similar-looking ASCII glyph, eg. uTorrent.

References

1.^ Olympus History : (Stylus) Series

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