what does represent quaternions addition?greenspun.com : LUSENET : quaternions : One Thread
I know that if q1 and q2 indicate rotations, then q2q1 represents the composite rotation of q1 followed by q2.
but what about addition?
-- luis opazo (firstname.lastname@example.org), March 05, 2004
Think of it as a combination of scalar and vector addition. The scalars add together like scalars always do, and the vector addition leads to a new vector pointing a new way (unless the vectors are collinear).
Only a particular subgroup of quaternions are about rotations, those that are unitary (have a norm of one). If the norm is not one, then there is a rotation along with an expansion or contraction.
-- Douglas Sweetser (email@example.com), March 07, 2004.