representation (i.e. a dimension). I just couldn't think of any other meaningful operation.
I believe that vector operator-(point,point) is sensible...
space. You can add Kelvin to Kelvin and Celsius to Celsius, but you can't mix them. The corresponding results are either in
In this case, since the metric is degenerate, they can be implicitly converted to one another if you're talking about temperature differences.
293.15 Kelvin represent the same temperature as 20 degrees Celsius, but doubling both will lead to very different results.
If you mean 293.15K in absolute temperature, you're right. However, doubling a temperature difference makes perfect sense in either unit system.
something entirely different. So I'd stick to offer a transformation between absolute temperatures.
But in most ways differences behave more like what we expect when we use units. That is a length, for example, is really a difference between the two endpoints of an object, etc... Since people are likely to expect reasonable handling of both absolute temperatures and temperature differences, we may end up adding the absolute<> wrapper to the units library to allow that intent to be indicated and caught. Relative values are basically degenerate with bare value type and probably don't need a special wrapper. Then the operations that need to be supported are : absolute<T> operator+(absolute<T>,T) absolute<T> operator+(T,absolute<T>) absolute<T> operator-(absolute<T>,T) absolute<T> operator-(T,absolute<T>) T operator-(absolute<T>,absolute<T>) I think that's about it. You can't multiply absolute values by scalars or add them to themselves, obviously. Of course, this functionality certainly has relevance beyond the dimensional analysis/units domain, but I don't know if it's possible to find a sufficiently generic solution that meets every reasonable need and is implementable... Matthias