On Aug 24, 2006, at 7:24 PM, Andy Little wrote:
energy = force*distance; // should this be allowed? torque = force*distance; // should this be allowed?
Quan allows this as it stands.
Good.
I think that in both cases the implicit conversion from the (annonymous?) quantity force*distance to either energy or torque. I think that to make the library usable one needs to allow these conversions.
The temporary result of force * distance is a so-called anonymous quantity.
OK
If one want to prevent the operations then because one is a vector scalar product (the energy) and the other a vector cross product (the torque) then this should be done at the level of the value_type of the quantity and not at the unit level.
Yes the obvious way to make a quantity a vector quantity is simple. Put it as the value_type of a vector. Currently quan has 2D and 3D vectors in separate namespaces, but it was suggested that it would be more flexible to just have a quan::simple_vector<N_dimensions,quantity> and hopefully that will be implemented at some stage.
Why not just use a ublas vector or MTL vector with a quan quantity? As i mentioned before I see no reason for reinventing the wheel. I still have not seen your reason for having your own vector classes. Matthias