Re: [boost] units review

I think you would need to write the equivalent of a computer algebra system to track what variables are "independent", and you would have to do so across programming boundaries in a non-trivial way.

Kevin, Thanks for the thorough synopsis - clearly, the covariance issue is the least of the challenges here. You're probably right that it is basically impossible to implement in full generality without huge runtime overhead since you would need to track the complete history of operations for every variable... Matthias