From: AdaMagica on
Dimension checking in Ada made simple. All 7 SI units are included;
Centigrade and other temperature skales.

Runtime checks can easily be switched off by changing only a few lines
of code, i.e. only the numerics remains.
IO with unit information is included, e.g. 10.0*km/h. Easy definition
of arbitrary other units.
3D vector spaces. Rotation via matrices or quaternions.

Examples of use and a lot of unit tests are provided.

http://www.christ-usch-grein.homepage.t-online.de/Ada/SI.html

This version fixes a bug in the definition of photometry unit lm=cd*sr.