Rho
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Rho (/ˈroʊ/; uppercase . Its uppercase form uses the same glyph,
Uses
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/d/df/NAMA_Alphabet_grec.jpg/220px-NAMA_Alphabet_grec.jpg)
Greek
[edit]Rho is classed as a liquid consonant (together with Lambda and sometimes the nasals Mu and Nu), which has important implications for morphology. In both Ancient and Modern Greek, it represents an alveolar trill IPA: [r], alveolar tap IPA: [ɾ], or alveolar approximant IPA: [ɹ].
In polytonic orthography, a rho at the beginning of a word is written with a rough breathing, equivalent to h (ῥ rh), and a double rho within a word is written with a smooth breathing over the first rho and a rough breathing over the second (ῤῥ rrh). That apparently reflected an aspirated or voiceless pronunciation in Ancient Greek, which led to the various Greek-derived English words starting with rh or containing rrh.
The name of the letter is written in Greek as ῥῶ (polytonic) or
Other alphabets
[edit]Letters that arose from rho include Roman R and Cyrillic Er (Р).
Mathematics and science
[edit]The characters
- In the physical sciences to represent:
- Densities: mass density, air density or charge density (
ρ ) - Resistivity (
ρ ) - Rho meson (
ρ +,ρ −,ρ 0) - General quantum states
- Hammett Equation,
ρ is used to represent the reaction constant, this is independent of the position and nature of the substituents of the benzene ring.
- Densities: mass density, air density or charge density (
- In mathematics to represent:
- A length coordinate in polar, cylindrical, spherical, and toroidal coordinate systems, and toroidal and poloidal coordinates of the Earth's magnetic field.
- The correlation coefficient of a population parameter
- The spectral radius of a matrix denoted as
- The plastic ratio
- The prime constant
- The sensitivity to interest rates of a pricing function
- The expected return of a given policy () in reinforcement learning, denoted
- The rename operation in relational algebra
- In economics to represent the discount rate of future pence cash flows
- In molecular biology to represent the Rho protein responsible for termination of RNA synthesis. In such occasions, it is often represented as U+03F1 ϱ GREEK RHO SYMBOL, to avoid confusion with the Latin letter p
- In molecular biology to represent the Rho family of GTPases, important for cytoskeletal dynamic regulation.
- In ecology to represent the population damping ratio where
ρ =λ 1 / |λ 2|. - In computer programming
- The lower-case rho "⍴" means reshape in the APL programming language, and by extension also queries shape
- The lower-case rho "
ρ " is used for the unary rename operation in relational algebra
- In statistics to represent Spearman's rank correlation coefficient, commonly known as Spearman's rho
- In options theory to represent the rate of change of a portfolio with respect to interest rates
Chi Rho (☧)
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/7b/Simple_Labarum2.svg/137px-Simple_Labarum2.svg.png)
The letter rho overlaid with chi forms the Chi Rho symbol, used to represent Jesus Christ. It was first used by Emperor Constantine the Great. A can be seen on his standard known as the Labarum.
Rho with stroke (ϼ)
[edit]The rho with a stroke through its tail is used for abbreviations involving rho, most notably in
Character encodings
[edit]Preview | Ῥ | ῥ | ῤ | |||||||
---|---|---|---|---|---|---|---|---|---|---|
Unicode name | GREEK CAPITAL LETTER RHO | GREEK SMALL LETTER RHO | GREEK CAPITAL LETTER RHO WITH DASIA | GREEK SMALL LETTER RHO WITH DASIA | GREEK SMALL LETTER RHO WITH PSILI | |||||
Encodings | decimal | hex | dec | hex | dec | hex | dec | hex | dec | hex |
Unicode | 929 | U+03A1 | 961 | U+03C1 | 8172 | U+1FEC | 8165 | U+1FE5 | 8164 | U+1FE4 |
UTF-8 | 206 161 | CE A1 | 207 129 | CF 81 | 225 191 172 | E1 BF AC | 225 191 165 | E1 BF A5 | 225 191 164 | E1 BF A4 |
Numeric character reference | Ρ |
Ρ |
ρ |
ρ |
Ῥ |
Ῥ |
ῥ |
ῥ |
ῤ |
ῤ |
Named character reference | Ρ | ρ | ||||||||
DOS Greek | 144 | 90 | 168 | A8 | ||||||
DOS Greek-2 | 199 | C7 | 235 | EB | ||||||
Windows 1253 | 209 | D1 | 241 | F1 | ||||||
TeX | \rho |
Greek rho symbols
[edit]Preview | ϱ | ϼ | ᴩ | ᵨ | ☧ | |||||
---|---|---|---|---|---|---|---|---|---|---|
Unicode name | GREEK RHO SYMBOL | GREEK RHO WITH STROKE SYMBOL | GREEK LETTER SMALL CAPITAL RHO | GREEK SUBSCRIPT SMALL LETTER RHO | CHI RHO | |||||
Encodings | decimal | hex | dec | hex | dec | hex | dec | hex | dec | hex |
Unicode | 1009 | U+03F1 | 1020 | U+03FC | 7465 | U+1D29 | 7528 | U+1D68 | 9767 | U+2627 |
UTF-8 | 207 177 | CF B1 | 207 188 | CF BC | 225 180 169 | E1 B4 A9 | 225 181 168 | E1 B5 A8 | 226 152 167 | E2 98 A7 |
Numeric character reference | ϱ |
ϱ |
ϼ |
ϼ |
ᴩ |
ᴩ |
ᵨ |
ᵨ |
☧ |
☧ |
Named character reference | ϱ, ϱ | |||||||||
TeX | \varrho |
Coptic ro
[edit]Preview | Ⲣ | ⲣ | ⳩ | |||
---|---|---|---|---|---|---|
Unicode name | COPTIC CAPITAL LETTER RO | COPTIC SMALL LETTER RO | COPTIC SYMBOL CHI RHO | |||
Encodings | decimal | hex | dec | hex | dec | hex |
Unicode | 11426 | U+2CA2 | 11427 | U+2CA3 | 11497 | U+2CE9 |
UTF-8 | 226 178 162 | E2 B2 A2 | 226 178 163 | E2 B2 A3 | 226 179 169 | E2 B3 A9 |
Numeric character reference | Ⲣ |
Ⲣ |
ⲣ |
ⲣ |
⳩ |
⳩ |
Functional symbol
[edit]Preview | ⍴ | |
---|---|---|
Unicode name | APL FUNCTIONAL SYMBOL RHO | |
Encodings | decimal | hex |
Unicode | 9076 | U+2374 |
UTF-8 | 226 141 180 | E2 8D B4 |
Numeric character reference | ⍴ |
⍴ |
Mathematical rho
[edit]Preview | 𝚸 | 𝛒 | 𝛠 | 𝛲 | 𝜌 | |||||
---|---|---|---|---|---|---|---|---|---|---|
Unicode name | MATHEMATICAL BOLD CAPITAL RHO |
MATHEMATICAL BOLD SMALL RHO |
MATHEMATICAL BOLD RHO SYMBOL |
MATHEMATICAL ITALIC CAPITAL RHO |
MATHEMATICAL ITALIC SMALL RHO | |||||
Encodings | decimal | hex | dec | hex | dec | hex | dec | hex | dec | hex |
Unicode | 120504 | U+1D6B8 | 120530 | U+1D6D2 | 120544 | U+1D6E0 | 120562 | U+1D6F2 | 120588 | U+1D70C |
UTF-8 | 240 157 154 184 | F0 9D 9A B8 | 240 157 155 146 | F0 9D 9B 92 | 240 157 155 160 | F0 9D 9B A0 | 240 157 155 178 | F0 9D 9B B2 | 240 157 156 140 | F0 9D 9C 8C |
UTF-16 | 55349 57016 | D835 DEB8 | 55349 57042 | D835 DED2 | 55349 57056 | D835 DEE0 | 55349 57074 | D835 DEF2 | 55349 57100 | D835 DF0C |
Numeric character reference | 𝚸 |
𝚸 |
𝛒 |
𝛒 |
𝛠 |
𝛠 |
𝛲 |
𝛲 |
𝜌 |
𝜌 |
Preview | 𝜚 | 𝜬 | 𝝆 | 𝝔 | 𝝦 | |||||
---|---|---|---|---|---|---|---|---|---|---|
Unicode name | MATHEMATICAL ITALIC RHO SYMBOL |
MATHEMATICAL BOLD ITALIC CAPITAL RHO |
MATHEMATICAL BOLD ITALIC SMALL RHO |
MATHEMATICAL BOLD ITALIC RHO SYMBOL |
MATHEMATICAL SANS-SERIF BOLD CAPITAL RHO | |||||
Encodings | decimal | hex | dec | hex | dec | hex | dec | hex | dec | hex |
Unicode | 120602 | U+1D71A | 120620 | U+1D72C | 120646 | U+1D746 | 120660 | U+1D754 | 120678 | U+1D766 |
UTF-8 | 240 157 156 154 | F0 9D 9C 9A | 240 157 156 172 | F0 9D 9C AC | 240 157 157 134 | F0 9D 9D 86 | 240 157 157 148 | F0 9D 9D 94 | 240 157 157 166 | F0 9D 9D A6 |
UTF-16 | 55349 57114 | D835 DF1A | 55349 57132 | D835 DF2C | 55349 57158 | D835 DF46 | 55349 57172 | D835 DF54 | 55349 57190 | D835 DF66 |
Numeric character reference | 𝜚 |
𝜚 |
𝜬 |
𝜬 |
𝝆 |
𝝆 |
𝝔 |
𝝔 |
𝝦 |
𝝦 |
Preview | 𝞀 | 𝞎 | 𝞠 | 𝞺 | 𝟈 | |||||
---|---|---|---|---|---|---|---|---|---|---|
Unicode name | MATHEMATICAL SANS-SERIF BOLD SMALL RHO |
MATHEMATICAL SANS-SERIF BOLD RHO SYMBOL |
MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL RHO |
MATHEMATICAL SANS-SERIF BOLD ITALIC SMALL RHO |
MATHEMATICAL SANS-SERIF BOLD ITALIC RHO SYMBOL | |||||
Encodings | decimal | hex | dec | hex | dec | hex | dec | hex | dec | hex |
Unicode | 120704 | U+1D780 | 120718 | U+1D78E | 120736 | U+1D7A0 | 120762 | U+1D7BA | 120776 | U+1D7C8 |
UTF-8 | 240 157 158 128 | F0 9D 9E 80 | 240 157 158 142 | F0 9D 9E 8E | 240 157 158 160 | F0 9D 9E A0 | 240 157 158 186 | F0 9D 9E BA | 240 157 159 136 | F0 9D 9F 88 |
UTF-16 | 55349 57216 | D835 DF80 | 55349 57230 | D835 DF8E | 55349 57248 | D835 DFA0 | 55349 57274 | D835 DFBA | 55349 57288 | D835 DFC8 |
Numeric character reference | 𝞀 |
𝞀 |
𝞎 |
𝞎 |
𝞠 |
𝞠 |
𝞺 |
𝞺 |
𝟈 |
𝟈 |
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
[edit]References
[edit]- ^ Paul of Aegina explains conventional usage in the last chapter of Book VII on weights and measures and uses it throughout his work.
- ^ Unicode Code Charts: Greek and Coptic (Range: 0370-03FF)