P=X5+X4−2X3+ 3X−1
(a0, a1, a2, a3, a4, a5, ...)=(−1,3,0,−2,1,1,0, ...).
PpPi
(−1,0,1,0, ...),(3,−2,1,0, ...),
Pp=X2−1, Pi= 3 −2X+X2.
P(X) = X
n≥0
a2nX2n+X
n≥0
a2n+1X2n+1 =X
n≥0
a2n(X2)n+XX
n≥0
a2n+1(X2)n=Pp(X2) + XPi(X2).
A2=λ1λ20
0λ1λ2=λ1λ2Id2.
∀n≥0, A2n= (λ1λ2)nId2, A2n+1 = (λ1λ2)nA.
P(A) = Pi(λ1λ2)A+Pp(λ1λ2)Id2=Pp(λ1λ2)λ1Pi(λ1λ2)
λ2Pi(λ1λ2)Pp(λ1λ2).
A
A=0A1
A20,
A1A2
A2=A1A20
0A2A1, A3=0A1A2A1
A2A1A20.
A2n=(A1A2)n0
0 (A2A1)n, A2n+1 =0A1(A2A1)n
A2(A1A2)n0.
P(A) = Pp(A1A2)A1Pi(A2A1)
A2Pi(A1A2)Pp(A2A1).