other
directory, written in UserRPL by John Wilson, that I have translated
into SysRPL, it is named TNBA for tangent, normal, binormal,
acceleration. It takes a 3-dimensional vector (as a list) at level
1 (e.g. { '2*T' 1 'T^2' }) and returns the position,
tangent, normal and binormal vectors as well as the
tangential and normal acceleration.