Rho
The title of this article is ambiguous. Other meanings are listed under RHO
The Rho (Modern Greek neuter Ρω, majuscule Ρ, minuscule ρ or ϱ) is the 17th letter of the Greek alphabet and has a numerical value of 100 according to the Milesian principle.
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Evidence is lacking for the following statement, especially with regard to foreign words.
- Liddell & Scott (A Greek-English Lexicon, 4th ed, 1855) record ᾿Ρᾶρος, ᾿Ράριος with spiritus lenis, but also mention ῾Ράρος (with spiritus asper) in the former, and write to the letter Rho: "Ρ, ρ [....] C. if ρ begins a word, it takes the rough breathing, except only in ῾Ράρος and ᾿Ράριος: though indeed in Aeol. ρ was never aspirated."
In some digitized works it is similar (LSJ, A Greek-English Lexicon & LS, An Intermediate Greek-English Lexicon have "Ρ̓ᾶρος" and "*)ra=ros" respectively, i.e. capitalized and spiritus lenis r). - With names like Raphael a Greek origin *᾿Ραφαήλ (with Spiritus lenis) instead of ῾Ραφαήλ (with Spiritus asper) would be conceivable, which could possibly also fit better to the Hebrew. Liddell & Scott do not record the word - possibly because it is too young - i.e. the statement of Liddell & Scott with the two exceptions is not necessarily correct for later times.
At the beginning of an ancient Greek word it is always aspirated/breathed e.g. ῥέω (rhéō) I flow.
Usage
- In physics, the small Rho
- the sign for density, for example, the mass density of water (~) 1 kilogram per liter,
- and that for the specific electrical resistance, a temperature-dependent material constant,
- the identifier of a meson,
- the sign for the charge density,
- the density matrix, a representation of the density operator (for systems in quantum mechanically defined states).
- In chemistry, the small Rho is a (non-standard) formula symbol for mass concentration.
- In statistics, the small Rho is a commonly used symbol for the correlation coefficient.
- In linear algebra and functional analysis, the spectral radius is denoted by a small Rho.
- In surveying, the conversion factor between radians and other angular measures is denoted by a small Rho: ρ = 180/π for alt degree, ρ = 200/π for gon, ... It finds use, for example, in formulas such as α/ρ = b/r, which is usually written α = b/r as the ratio of the central angle to the arc piece outside of surveying.
- In linguistics, the sound change to r is called rhotacism.
- In queueing theory, it is the utilization rate.
- In economics, ρ
- one of the key figures for valuing an option and
- in growth models is usually a parameter that reflects the time preference of household consumption.
Character encoding
| Majuscule Ρ | minuscule ρ | Minuscule ϱ (variant) | |
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