From: Amitha Perera <perera@cs...>  20011111 15:37:22

[vnl] angle(a,b) now returns acos( a.b / ab ), but is not instantiated for complexvalued vectors, since we lack an implementation for acos(complex). Amitha. On Mon, Oct 29, 2001 at 03:03:29PM 0500, Amitha Perera wrote: > > Apparently this is meant to give "symmetric" output, i.e., > > angle(a,b) == angle(b,a). > > By definition of the cos_angle, it is already symmetric: > cos_angle(a,b) = cos_angle(b,a) = a.b/(ab). The current > implementation gives > > ^ > / > / > A / B > </..... > > B as the "angle", which is the smallest angle provided the "vectors" > are undirected. Is this what is intended? I think it should simply be > acos( a.b / ab ) > since that is what most people refer to as the angle between two > vectors. > > Amitha. 