Nu ( ell, νι ''ni'' ) is the 13th letter of the
Greek alphabet (uppercase Ν, lowercase ν), representing the
voiced alveolar nasal . In the system of
Greek numerals
Greek numerals, also known as Ionic, Ionian, Milesian, or Alexandrian numerals, are a system of writing numbers using the letters of the Greek alphabet. In modern Greece, they are still used for ordinal numbers and in contexts similar to tho ...
it has a value of 50. It is derived from the ancient Phoenician language
nun
A nun is a woman who vows to dedicate her life to religious service, typically living under vows of poverty, chastity, and obedience in the enclosure of a monastery or convent.''The Oxford English Dictionary'', vol. X, page 599. The term is o ...
. Its
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
equivalent is
N, though the lowercase (
) resembles the Roman lowercase
v.
The name of the letter is written in
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...
and traditional
Modern Greek polytonic orthography
Greek orthography has used a variety of diacritics starting in the Hellenistic period. The more complex polytonic orthography ( el, πολυτονικό σύστημα γραφής, translit=polytonikó sýstīma grafī́s), which includes fi ...
, while in
Modern Greek it is written .
Letters that arose from nu include Roman
N and Cyrillic
Н.
Symbology
Like
Mu, the uppercase Nu is normally identical to Latin
N and is therefore not used internationally in scientific or mathematical contexts. The lower-case letter is used as a symbol for:
* Mathematics:
**
Degree of freedom
Degrees of freedom (often abbreviated df or DOF) refers to the number of independent variables or parameters of a thermodynamic system. In various scientific fields, the word "freedom" is used to describe the limits to which physical movement or ...
in
statistics.
** The
greatest fixed point
In order theory, a branch of mathematics, the least fixed point (lfp or LFP, sometimes also smallest fixed point) of a function from a partially ordered set to itself is the fixed point which is less than each other fixed point, according to the ...
of a function, as commonly used in the
μ-calculus.
** Free names of a process, as used in the
π-calculus
In theoretical computer science, the -calculus (or pi-calculus) is a process calculus. The -calculus allows channel names to be communicated along the channels themselves, and in this way it is able to describe concurrent computations whose netw ...
.
** One of
the Greeks in
mathematical finance, known as "vega".
** The reciprocal of 1 plus the interest rate in finance.
** The
-adic valuation or -adic order of a number.
*Physics:
**
Kinematic viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water.
Viscosity quantifies the int ...
in
fluid mechanics.
** The
frequency of a wave in physics and other fields; sometimes also
spatial frequency
In mathematics, physics, and engineering, spatial frequency is a characteristic of any structure that is periodic across position in space. The spatial frequency is a measure of how often sinusoidal components (as determined by the Fourier tra ...
;
wavenumber
** The
specific volume
In thermodynamics, the specific volume of a substance (symbol: , nu) is an intrinsic property of the substance, defined as the ratio of the substance's volume () to its mass (). It is the reciprocal of density (rho) and it is related to the m ...
in
thermodynamics.
**
Poisson's ratio
In materials science and solid mechanics, Poisson's ratio \nu ( nu) is a measure of the Poisson effect, the deformation (expansion or contraction) of a material in directions perpendicular to the specific direction of loading. The value of Po ...
, the ratio of strains perpendicular with and parallel with an applied force.
** Any of three kinds of
neutrino
A neutrino ( ; denoted by the Greek letter ) is a fermion (an elementary particle with spin of ) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass ...
in particle physics.
** The number of
neutrons released per
fission of an atom in nuclear physics.
** Molecular
vibrational mode
A normal mode of a dynamical system is a pattern of motion in which all parts of the system move sinusoidally with the same frequency and with a fixed phase relation. The free motion described by the normal modes takes place at fixed frequencies. ...
, where x is the number of the vibration (a label).
** The
true anomaly, an angular parameter that defines the position of a body moving along an orbit (see
orbital elements).
*Biology:
**
A DNA polymerase found in higher
eukaryotes and implicated in
translesion synthesis
DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA dama ...
.
*Chemistry:
** The
stoichiometric coefficient
A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and chemical formulas. The reactant entities are given on the left-hand side and the product entities on the right-hand side with a plus sign between ...
.
*Psychology:
** The maximum conditioning possible for an
unconditioned stimulus in the
Rescorla-Wagner model.
Character encodings
Greek Nu/Coptic Ni
Encodings of Greek Nu and Coptic Ni.
[Unicode Code Charts]
Greek and Coptic (Range: 0370-03FF)
/ref>
BBX Mathematical Nu
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.
See also
* Movable nu
In ancient Greek grammar, movable nu, movable N or ephelcystic nu ( grc, νῦ ἐφελκυστικόν ''nû ephelkustikón'', literally "nu dragged onto" or "attracted to") is a letter nu (written ; the Greek equivalent of the letter ''n'') pl ...
* N, v
References
{{DEFAULTSORT:Nu (Letter)
Greek letters