Units-filter is a basic standalone filter written in C language, flex and bison. It inputs strings like "1.5e3 nN.m.s^-1" (it could be the time growth ratio of a torque) and outputs the value in standard SI unit, followed by the physical dimension of this value.

example :~/src$ echo 1.5e3 nN.m.s^-1 | units-filter 1.5e-06   2   1  -3   0   0   0   0    0    0

2 -3 which means : 1.5e-06 (SI unit) m .kg.s

This parser can be embedded in educational test systems, in order to analyze a student's answer to a problem of physics or chemistry.