Construct a unit pure quaternion orthogonal to another
U = orthogonal(V, W)
orthogonal(V, W) constructs and returns a unit pure quaternion orthogonal to V, and W if given. V and W must be pure quaternions, but need not have unit modulus. W need not be orthogonal to V, but it must not be parallel. The function works for the complex quaternion case as well as for real quaternions.
>> orthogonal(qi, qj) ans = 0 * I + 0 * J + 1 * K