
ϕ
2
(x
i
)
ϕ
2
(x
i
) = x
2
i
−
n
P
i=1
x
2
i
ϕ
1
(x
i
)
n
P
i=1
ϕ
2
1
(x
i
)
ϕ
1
(x
i
) −
n
P
i=1
x
2
i
ϕ
0
(x
i
)
n
P
i=1
ϕ
2
0
(x
i
)
ϕ
0
(x
i
).
ϕ
s
(x
i
)
ϕ
s
(x
i
) = x
s
i
−
n
P
i=1
x
s
i
ϕ
s−1
(x
i
)
n
P
i=1
ϕ
2
s−1
(x
i
)
ϕ
s−1
(x
i
)−. . .−
n
P
i=1
x
s
i
ϕ
0
(x
i
)
n
P
i=1
ϕ
2
0
(x
i
)
ϕ
0
(x
i
),
ϕ
s
(x
i
) = x
s
i
+ b
s−1
ϕ
s−1
(x
i
) + . . . + b
0
ϕ
0
(x
i
).
b
q
q < s
n
X
i=1
x
s
i
ϕ
q
(x
i
) + b
q
n
X
i=1
ϕ
2
q
(x
i
) = 0, b
q
= −
n
P
i=1
x
s
i
ϕ
q
(x
i
)
n
P
i=1
ϕ
2
q
(x
i
)
.
ˆ
θ
s
ˆ
θ
s
=
n
X
j=1
ϕ
sj
u
j
, s = 0, 1, 2, . . . , S − 1,
ˆ
~
θ = Φ~u,