During the last days I’ve been working on a small new package:

The physical constants are defined as `Constant`

objects, which can be turned into `Quantity`

objects (from

`Unitful.jl`

package) or `Measurement`

objects (from `Measurements.jl`

package) at request.

An example is worth a thousand words:

```
julia> using PhysicalConstants.CODATA2014
julia> c
Speed of light in vacuum (c)
Value = 2.99792458e8 m s^-1
Standard uncertainty = (exact)
Relative standard uncertainty = (exact)
Reference = CODATA 2014
julia> G
Newtonian constant of gravitation (G)
Value = 6.67408e-11 m^3 kg^-1 s^-2
Standard uncertainty = 3.1e-15 m^3 kg^-1 s^-2
Relative standard uncertainty = 4.6e-5
Reference = CODATA 2014
julia> float(G)
6.67408e-11 m^3 kg^-1 s^-2
julia> 4pi * float(G) / float(c)^2
9.331680614932136e-27 m kg^-1
julia> using Measurements
julia> measurement(ħ)
1.0545718001391127e-34 ± 1.2891550390443523e-42 J s
julia> measurement(BigFloat, ħ)
1.054571800139112651153941068725066773746246506229852090971714108355028066256094e-34 ± 1.289155039044352219727958483317366332479123130497697234856105486877064060837251e-42 J s
julia> big(ħ) / (big(h) / (2 * big(pi)))
1.0
```

`Constants.jl`

is not yet registered because I’d like first to address a couple of design issues. If you’re interested in this package, please chime in: https://github.com/JuliaPhysics/PhysicalConstants.jl/issues