I had written a tangentially related comment a few days ago. Its related to rotation in a plane. In that case things become a lot simpler, especially if your pr

I had written a tangentially related comment a few days ago. Its related to rotation in a plane. In that case things become a lot simpler, especially if your programming environment support operations on complex numbers as a first class citizen. https://news.ycombinator.com/item?id=40333541 https://news.ycombinator.com/item?id=40333541 The key intuition is that additions are translations and multiplications are rotations. So two model average translation one can use arithmetic mean, for average rotation the geometric mean.