
f(r, ϕ) =
1
2π
2
∞
Z
−∞
π
Z
0
1
r cos(θ − ϕ) − n
∂u(n, θ)
∂n
dndθ
f(r, ϕ) =
˜
R
−1
[u(n, θ)].
˜
R
−1
= −
1
2π
P HD,
D : q(n, θ) = D[u(n, θ)] = lim
∆n→0
u(n + ∆n, θ) − u(n, θ)
∆n
H : h(n
′
, θ) = H[q(n
′
, θ)] = −
1
π
lim
ε→0
{
n
′
−ε
Z
−∞
q(n, θ)
n
′
− n
dn +
∞
Z
n
′
+ε
q(n, θ)
n
′
− n
dn}