Nu (letter)

For other uses, see Nu (disambiguation).

Not to be confused with Mu (letter), N, or En (Cyrillic).

Nu (/ˈnjuː/; uppercase Ν, lowercase ν; Greek: vι ni [ni]) is the thirteenth letter of the Greek alphabet, representing the voiced alveolar nasal IPA: [n]. In the system of Greek numerals it has a value of 50. It is derived from the Phoenician nun . Its Latin equivalent is N, though the lowercase ($\nu$) resembles the Roman lowercase v.

The name of the letter is written νῦ in Ancient Greek and traditional Modern Greek polytonic orthography, while in Modern Greek it is written νι [ni].

Letters that arose from nu include Roman N and Cyrillic script En.

Symbology

Bust of Nikos Kazantzakis with the traditional Greek nu

The lower-case letter ν is used as a symbol in many academic fields. Uppercase nu is not used, because it appears identical to Latin N.

• Mathematics:
  • Degrees of freedom in statistics.
  • The greatest fixed point of a function, as commonly used in the μ-calculus.
  • Free names of a process, as used in the π-calculus.
  • One of the Greeks in mathematical finance, known as "vega".
  • The reciprocal of 1 plus the interest rate in finance.
  • The p-adic valuation or p-adic order of a number.
• Physics:
  • Kinematic viscosity in fluid mechanics.
  • The frequency of a wave in physics and other fields; sometimes also spatial frequency; wavenumber
  • The specific volume in thermodynamics.
  • Poisson's ratio, the ratio of strains perpendicular with and parallel with an applied force.
  • Any of three kinds of neutrino in particle physics.
  • The number of neutrons released per fission of an atom in nuclear physics.
  • Molecular vibrational mode, ν_x 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.
• Chemistry:
  • The stoichiometric coefficient.
• Psychology:
  • The maximum conditioning possible for an unconditioned stimulus in the Rescorla-Wagner model.

Unicode

Encodings of Greek Nu and Coptic Ni.

• U+039D Ν GREEK CAPITAL LETTER NU (Ν)
• U+03BD ν GREEK SMALL LETTER NU (ν) (\nu in TeX)
• U+2C9A Ⲛ COPTIC CAPITAL LETTER NI
• U+2C9B ⲛ COPTIC SMALL LETTER NI

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:

• U+1D6B4 𝚴 MATHEMATICAL BOLD CAPITAL NU
• U+1D6CE 𝛎 MATHEMATICAL BOLD SMALL NU
• U+1D6EE 𝛮 MATHEMATICAL ITALIC CAPITAL NU
• U+1D708 𝜈 MATHEMATICAL ITALIC SMALL NU
• U+1D728 𝜨 MATHEMATICAL BOLD ITALIC CAPITAL NU
• U+1D742 𝝂 MATHEMATICAL BOLD ITALIC SMALL NU
• U+1D762 𝝢 MATHEMATICAL SANS-SERIF BOLD CAPITAL NU
• U+1D77C 𝝼 MATHEMATICAL SANS-SERIF BOLD SMALL NU
• U+1D79C 𝞜 MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL NU
• U+1D7B6 𝞶 MATHEMATICAL SANS-SERIF BOLD ITALIC SMALL NU

See also

• Movable nu