
A, Q ∈ R
n×n
X ∈ R
n×n
Q V
S
n
(n ×n)
R
m
m = n(n+1)/2 {E
1
, ···, E
m
}
X =
P
m
j=1
x
j
E
j
Q +
m
X
j=1
x
j
(A
T
E
j
+ E
j
A) > 0 ,
A =
0 1
2 3
, Q =
0 0
0 0
,
X = x
1
1 0
0 0
+ x
2
0 1
1 0
+ x
3
0 0
0 1
=
x
1
x
2
x
2
x
3
x
1
0 1
1 0
+ x
2
4 3
3 2
+ x
3
0 2
2 6
> 0 .
> ≥
F (x) < 0 F (x) > G(x) F (x) G(x)
−F (x) > 0 F (x) − G(x) > 0
x F = {x| F (x) > 0}
x
1
, x
2
∈ F α ∈ [0, 1] F (x)
F (αx
1
+ (1 − α)x
2
) = αF (x
1
) + (1 − α)F (x
2
) > 0 .
F
1
(x) > 0, ···, F
k
(x) > 0 .
F (x) =
F
1
(x) 0 ··· 0
0 F
2
(x) ··· 0
0 0 ··· F
k
(x)
> 0 .
F (x)
F
1
(x), ···, F
k
(x)