“…, n 4 }} on the point p 3,1 , with 1, j = 0. We can further decompose 1, j uniquely into a tangential component 1 1, j in the plane determined by three points p 3,1 , p 3,2 , p 3,3 and a tangential component 2 1, j in the plane determined by three points p 3,1 , p 3,3 , p 3,4 . The magnitude of the perturbation 1 1, j satisfies Eq.…”