You’re right, quaternions don’t go singular. I misremembered what the problem was. And the problem with the quaternions is that the multiple revolutions will re

You’re right, quaternions don’t go singular. I misremembered what the problem was. And the problem with the quaternions is that the multiple revolutions will resolve to the same quaternion and then you don’t know how many times you’ve revolved around. For some applications this is important to know.