<P> The characters ρ and ρ are also conventionally used outside the Greek alphabetical context in science and mathematics . </P> <Ul> <Li> In the physical sciences to represent: <Ul> <Li> Densities: mass density, air density or charge density (ρ) </Li> <Li> Resistivity (ρ) </Li> <Li> Rho meson (ρ, ρ, ρ) </Li> <Li> General quantum states </Li> <Li> 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 . </Li> </Ul> </Li> <Li> In mathematics to represent: <Ul> <Li> A length coordinate in polar, cylindrical, spherical, and toroidal coordinate systems, and toroidal and poloidal coordinates of the Earth's magnetic field . </Li> <Li> The correlation coefficient of a population parameter </Li> <Li> The spectral radius of a matrix A (\ displaystyle A) denoted as ρ (A) (\ displaystyle \ rho (A)) </Li> <Li> The plastic number </Li> <Li> The' prime constant' number </Li> <Li> The sensitivity to interest rates of a pricing function </Li> <Li> The expected return of a given policy (π (\ displaystyle \ pi)) in reinforcement learning, denoted ρ π (\ displaystyle \ rho ^ (\ pi)) </Li> </Ul> </Li> <Li> In economics to represent the discount rate of future pence cash flows </Li> <Li> In molecular biology to represent the Rho protein responsible for termination of RNA synthesis . In such occasions, it is often represented as ρ ("rho symbol" U + 03F1), to avoid confusion with the Latin letter p </Li> <Li> In ecology to represent the population damping ratio where ρ = λ1 / λ2 . </Li> <Li> In computer programming <Ul> <Li> For LaTeX, the symbols are \ rho (ρ (\ displaystyle \ rho)), and \ varrho (ρ (\ displaystyle \ varrho)) (note: \ Rho is not defined by default) </Li> <Li> The lower - case rho "ρ" has a special meaning in the APL programming language </Li> </Ul> </Li> <Li> In statistics to represent Spearman's rank correlation coefficient, commonly known as Spearman's rho </Li> <Li> In options theory to represent the rate of change of a portfolio with respect to interest rates </Li> </Ul> <Li> In the physical sciences to represent: <Ul> <Li> Densities: mass density, air density or charge density (ρ) </Li> <Li> Resistivity (ρ) </Li> <Li> Rho meson (ρ, ρ, ρ) </Li> <Li> General quantum states </Li> <Li> 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 . </Li> </Ul> </Li> <Ul> <Li> Densities: mass density, air density or charge density (ρ) </Li> <Li> Resistivity (ρ) </Li> <Li> Rho meson (ρ, ρ, ρ) </Li> <Li> General quantum states </Li> <Li> 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 . </Li> </Ul>

What does the greek letter rho mean in physics