<> <> <> <> Mik's Least Squares Derivation Mik Lamming, PARC/CSL May 11, 1987 Least Squares Derivation Let X be defined to be: X . Then we wish to compute: X and X . By the chain rule for differentiation, we have: X , and X , hence since X is X , and X is X , we have: X is X X is X