Length (earth radii) Time (minutes) Angle (radians)

So derived types would be:

Velocity (radians/minute)

Be careful to define this as angular velocity...

Now that I have described what types are required I have a few questions:

1. Where is the length type for already defined for earth radii?

In your header file? The library does not include earth radii as a unit of length, but it is easy to roll your own.

2. What advantage is there to creating my own unit system?

For most applications, it is not necessary to create a whole unit system; you should just define your desired base units and, possibly, conversion factors to SI or some other system.

It seems that my unit system would have:

- earth radii

Look at

- kg (useless in the equations)

If mass doesn't appear in any of your equations, it is not necessary to define or include it.

- minute

This already exists in the library :

- radians

This already exists in the library With a compiler that supports auto/decltype/typeof reasonably well, unit systems are now essentially an implementation detail for most uses of the library. Matthias