Physical unit systems (Metric, English, Natural, etc...)
Author chakravala
4 Stars
Updated Last
2 Years Ago
Started In
December 2020


Physical unit systems (Metric, English, Natural, etc...)

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Specifications for dimensional units are in the UnitSystems.jl and UnitfulSystems.jl repositories. The two packages are designed so that they can be interchanged if compatibility with Unitful.jl is desired or not. However, the UnitfulSystems package has fewer UnitSystem specifications available than the UnitSystems package due to limitations in combination with the Unitful package. Specifically, Metric, SI2019, CODATA, Conventional, MTS, EMU2019, English, and EnglishUS can have Unitful values; while Gauss, LorentzHeaviside, Thomson, EMU, ESU, ESU2019, IAU, FFF, Planck, PlanckGauss, Stoney, Hartree, Rydberg, Schrodinger, Electronic, Natural, NaturalGauss, QCD, QCDGauss, and QCDoriginal are plain valued.

pkg> add UnitSystems # or UnitfulSystems

julia> using UnitSystems

A UnitSystem is a consistent set of dimensional values selected to accomodate a particular use case or standardization. It is possible to convert derived physical quantities from any UnitSystem specification into any other using accurate values. In total, five fundamental constants kB,ħ,𝘤,μ₀,mₑ are used to specify a specific unit system. These are the constants of boltzmann, planckreduced, lightspeed, permeability, and electronmass. Different choices of natural units or physical measurements result in a variety of unit systems for many purposes.

Main documentation is at https://geophysics.crucialflow.com/dev/units

Another important additional definition is the molarmass constant Mᵤ, which is automatically selected based on the choice of boltzmann constant (but can also be customized if necessary). Historically, older electromagnetic unit systems also relied on a rationalization constant λ and a lorentz force proportionality constant αL. In most unit systems these extra constants have a value of 1 unless otherwise specified.


Fundamental constants of physics are: kB Boltzmann's constant, ħ reduced Planck's constant, 𝘤 speed of light, μ₀ vacuum permeability, mₑ electron rest mass, λ Gauss rationalization, and αL Lorentz's constant. Primarily the Metric SI unit system is used in addition to the historic English engineering unit system. These constants induce derived values for avogadro, boltzmann, universal, planck, planckreduced, lightspeed, planckmass, atomicmass, protonmass, electronmass, newton, einstein, permeability, permittivity, coulomb, and additional constants molarmass, hyperfine, luminousefficacy, stefan, radiationintensity, ampere, lorentz, biotsavart, rationalization, impedance, charge, magneton, conductance, faraday, magneticflux, josephson, klitzing, hartree, rydberg, bohr, and bohrreduced.

Physics constant documentation is at https://geophysics.crucialflow.com/dev/constants

Additional reference UnitSystem variants: EMU, ESU, Gauss, LorentzHeaviside, MTS, SI2019, CODATA, Conventional, IAU, EnglishUS; and natural atomic units based on gravitational coupling αG and the fine structure 1/αinv constant (Planck, PlanckGauss, Stoney, Hartree, Rydberg, Schrodinger, Electronic, Natural, NaturalGauss, QCD, QCDGauss, and QCDoriginal).

Unt conversion documentation is at https://geophysics.crucialflow.com/dev/convert

Derived Unit conversions:

Mechanics: time, length, area, volume, wavenumber, fuelefficiency, frequency, frequencydrift, speed, acceleration, jerk, snap, volumeflow, mass, massflow, lineardensity, areadensity, density, specificvolume, force, stiffness, pressure, compressibility, viscosity, diffusivity, rotationalinertia, momentum, angularmomentum, yank, energy, specificenergy, action, fluence, power, powerdensity, intensity, spectralflux, soundexposure, impedance, specificimpedance, admittance, compliance, inertance; Electromagnetics: charge, chargedensity, linearchargedensity, exposure, mobility, current, currentdensity, resistance, conductance, resistivity, conductivity, capacitance, inductance, reluctance, permeance, permittivity, permeability, susceptibility, specificsusceptibility, demagnetizingfactor, vectorpotential, electricpotential, magneticpotential, electricfield, magneticfield, electricflux, magneticflux, electricfluxdensity, magneticfluxdensity, electricdipolemoment, magneticdipolemoment, electricpolarizability, magneticpolarizability, magneticmoment, magnetizability, magnetization, specificmagnetization, rigidity, polestrength; Thermodynamics: temperature, entropy, specificentropy, volumeheatcapacity, thermalconductivity, thermalconductance, thermalresistance, thermalexpansion, lapserate, molarmass, molality, mole, molarity, molarvolume, molarentropy, molarenergy, molarconductivity, molarsusceptibility, catalysis, specificity, luminousflux, luminance, luminousenergy, luminousexposure, luminousefficacy.

Other similar packages include PhysicalConstants.jl, MathPhysicalConstants.jl, Unitful.jl, UnitfulSystems.jl, UnitfulUS.jl, UnitfulAstro.jl, UnitfulAtomic.jl, NaturallyUnitful.jl, and UnitfulMoles.jl.

Required Packages

No packages found.