Inside the Julia shell, you can download and install the package by issuing:

using Pkg
Pkg.add("UDUnits")

If you want to try the latest development version, you can do this with the following commands:

using Pkg
Pkg.add(PackageSpec(url="https://github.com/Alexander-Barth/UDUnits.jl", rev="master"))
Pkg.build("UDUnits")

The first step is to load the module UDUnits and to initialize the unit system sys which correspond to the SI unit system.

using UDUnits
sys = System()

The unit objects can be created for m and cm using either their symbol or their full name by indexing the sys object as if sys is a dictionary.

m = sys["meter"]
cm = sys["cm"]

Similarily to a dictionary, the function haskey is defined to determine if a unit is valid:

haskey(sys,"μm") # returns true since UDUnits knows about micrometers

Units can be derived using the usual mathemical operators. Of course, m_per_s could have been also create simply by using sys["m/s"].

m = sys["m"]
km = sys["km"]
s = sys["s"]
h = sys["h"]
m_per_s = m/s
km_per_h = km/h

The function areconvertible returns true if two units are convertible:

@show areconvertible(m_per_s,km_per_h)

To convert units, create a converter object and then apply the object to some data.

conv = Converter(m_per_s,km_per_h)
speed_in_m_per_s = 100.
speed_in_km_per_h = conv(speed_in_m_per_s)

The dot syntax can be used for an array as input:

speed_in_m_per_s = [100.,110.,120.]
speed_in_km_per_h = conv.(speed_in_m_per_s)

• Unitful.jl

• Documentation of the C-library