On Mon, Sep 17, 2012 at 12:11 AM, Ted Dunning <[email protected]> wrote:
> A_k = U_k U_k' A_k > Forgetting S_k is a bit dangerous here. It is true that > > U_k S_k = A_k V_k > > But, of course, right multiplying by V_k' gives us the identity above. > > I think that the real confusion is that I am talking about projecting back > into span A and you are talking about expressing things in terms of the > latent variables. Right, this goes all the way to "making recommendations", back to Ak. I think Lance was asking about how to find the new row in latent feature space, a row in Uk. You can't ignore Sk, yes, just trying to get to the essence. Putting it back in (half-and-half) does get what I posted which indeed is the project I think that was in question.. Uk * sqrt(Sk) = Ak * Vk * 1/sqrt(Sk)
