[R] package pls

[tsn4867]

    Hi,
    For the package "pls", I need to understand the algorithm for 
"simpls.fit" for Partial Least Squares. I'm not sure if simpls.fit tries 
to find the weight vectors (loadings) to maximize which of the two:  
Cov(Xw, y) or maximize Cov^2(Xw,y)? Are these objective functions 
equivalent? (in some texts, they use the first and in other texts, they 
use the second obj. function.). I think the algorithm for simpls.fit is 
using Cov(Xw,y).
     Also, can you give me some references where they state the 
equivalency of the two obj. functions?
                                                                                             
Thank you,
                                                                                           
Tuan Nguyen.