But is it actually QR of Y? On Tue, Jan 8, 2013 at 3:41 PM, Sean Owen <[email protected]> wrote:
> There's definitely a QR decomposition in there for me since solving A > = X Y' for X is X = A Y (Y' * Y)^-1 and you need some means to > compute the inverse of that (small) matrix. > > On Tue, Jan 8, 2013 at 5:27 PM, Ted Dunning <[email protected]> wrote: > > This particular part of the algorithm can be seen as similar to a least > > squares problem that might normally be solved by QR. I don't think that > > the updates are quite the same, however. > > > > On Tue, Jan 8, 2013 at 3:10 PM, Sebastian Schelter <[email protected]> > wrote: > > > >> This factorization is iteratively refined. In each iteration, ALS first > >> fixes the item-feature vectors and solves a least-squares problem for > >> each user and then fixes the user-feature vectors and solves a > >> least-squares problem for each item. > >> >
