A=∑40=∑414其中A=vO i=1 p"p=b,-y-1:- 441y=(o)/v1o/)="(av)o Vi oi L=j A是幂等矩阵 0 ≠ = = n i T i i i A v 1    = = n i i Ai 1  T i i i 其中, A = v  P P = En −1     = = i j i j v j T i 0 1  ( )( ) T j j T i j i i A A = v  v  T j j T i i = v ( v )      = = i j v i j T i i 0  Ai 是幂等矩阵