On 6/6/2009 2:03 PM Charles R Harris apparently wrote: > So is eye(3)*(v.T*v) valid? If (v.T*v) is 1x1 you have incompatible > dimensions for the multiplication Exactly. So it is not valid. As you point out, to make it valid implies a loss of the associativity of matrix multiplication. Not a good idea! Cheers, Alan