title: Find the axis around which there is the most rotation?
body: <p>Given a 3d rotation, is there a way to compute the axis around which the largest component of the rotation happens?</p>
  
  <p>To ground this in the actual task I'm attempting: I am getting data from a smartphone gyroscope and I want to figure out what axis the user is turning their phone around but without knowing anything other than the absolute rotation. This is using Java and Android.</p>