y = f (x1, x2, , xN) . . f uc (y).
(3) (23) :
, (24)
:
(25)
ui (y)(i = 1, 2,,N) , xi Xi , :
(26)
Y, Xi, . f ( , ) , .
u (xi) , ui (y) . , u (xi) .
u (xi) . Y=1X2, :
(27)
f Xi , i
:
f Xi i
( ):
(28)