SUBSPACE(A,B) finds the largest 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 COS(ABS(A'*B)) in exact arithmetic. This is a replacement for MATLAB's SUBSPACE.m Rev. 5.5-5.8 that fails to provide correct answers for angles smaller than e-8 and for Rev. 5.9-18.104.22.168 that fails to provide correct answers for angles close to pi/2.