P
1
, . . . , P
L
Q
1
, . . . , Q
L
IR
L
IR
K
c
1
≥ . . . ≥ c
L
≥ 0
X =
L
X
i=1
c
i
P
i
Q
T
i
.
X
1 c
d
> 0 c
d+1
= . . . = c
L
= 0.
2 c
2
i
= λ
i
1 ≤ i ≤ d.
3 i = 1, . . . , d P
i
XX
T
λ
i
.
4 Q
i
= X
T
P
i
/
√
λ
i
(i = 1, . . . , d).
5 c
i
(24) (23)
U
i
V
i
I ⊂ {1, . . . , d} J = {1, . . . , d} \ I
X
I
=
X
i∈I
p
λ
i
U
i
V
T
i
X
J
def
= X − X
I
X
J
=
X
i∈J
p
λ
i
U
i
V
T
i
X
J
U
d
= [U
1
: . . . : U
d
]
V
d
= [V
1
: . . . : V
d
] Λ
d
d × d
λ
i
i
X = U
d
Λ
1/2
d
V
T
d
,