A class of units of physical quantities for Ruby.

This class covers most functionality of UNIDATA's UDUNITS Library, however,
with a more sophisticated handling of string expressions.

UDUNITS always decomposes units into the four base units and discards the
original string expressions. Therefore, 'hPa' always becomes '100
kg.m-1.sec-1', and 'day' always becomes '86400 sec'. On the other hand, this
library tries to keep the original expressions as much as possible by default,
while allowing partial to complete decompositions if needed.

WWW: http://www.gfd-dennou.org/arch/ruby/products/numru-units/