** Angle between two subspaces. **

** SUBSPACE(A,B) finds the angle between two subspaces specified **

** by the columns of A and B. If A and B are vectors of unit **

** length, this is the same as ACOS (A'*B). **

** If the angle is small, the two spaces are nearly linearly **

** dependent. In a physical experiment described by some **

** observations A, and a second realization of the experiment **

** described by B, SUBSPACE(A,B) gives a measure of the amount **

** of new information afforded by the second experiment not **

** associated with statistical errors of fluctuations. **

** **