I want and need the boost.units functionality. I'm sure that this is what I want. But I've spend a lot of time going through the documentation and I'm having real difficulties figure out how to use this. There's a lot there so I feel that what I want must be in there somewhere. I've started going through the tutorial example and there are a couple of problems. First of all, it doesn't compile on my machine. Looking at the tutorial, it actually contains two programs - one of which is commented out. I tried the commented out one as well - it didn't compile either. Note that other than in the header, there are very few if any comments in this code. It doesn't qualify as a tutorial. What I expect to see is: #include <boost/units/quantity.hpp> #include <boost/units/systems/si/length.hpp> #include <boost/units/base_units/us/mile.hpp> void main(){ using namespace boost::units; using namespace boost::units::si; using namespace boost::units::us; quantity<length, float> l1; l1 = 1000.0 * meters; quantity<length, float> l2; l2 = 1.0 * miles; // compile error quantity<length, float> l3 = l1 + l2; } and I expect this to pretty much work. The documentation says " Implicit conversions between unit systems are allowed only when the reduced units are identical, allowing, for example, trivial conversions between equivalent units in different systems (such as SI seconds and CGS seconds)" so I expected that it can convert miles into kilometers. This is a disappointment - but I'll assume that the authors have a good reason for this. So I'm interest in figuring out how to fix this but the manual doesn't seem to help me. I know a huge amount of effort has been invested in this package, but I'm afraid this issue of documentation is a big obstacle to this package being used every where it could be. Note to authors of boost libraries. When you think you've got the documentation done, hand it to someone who isn't familiar with it and ask him to make a small example using the library in 30 minutes. If he can't do that, it's time to go back to work. Most users will give up if they can't get some sort of love back from the library in that amount of time. Robert Ramey