find the rotation matrix between two vectors

[Junqian Gordon Xu]

I'm trying to find the rotation matrix or quaternion from two unit 
vectors A and B, then to apply the rotation to a third vector C.

I played with the quaternion package on octave-forge, but the 
documentation is not complete and the `demoquat` does not work well 
under 3.2.4.

My knowledge of quaternion is quite limited. Does anybody have any 
suggestion on how to achieve this easily in octave?

Thanks
Gordon