what is the general solution of the poisson equation :
∂2A/∂r2 + 1/r ∂A/∂r + 1/r2 ∂2A/∂θ2 = f(r,θ)
the function f(r,θ) is :
f(r,θ)=1/r (Ʃ Xncos(nθ) + Ynsin(nθ))
where the boundary is :
I(a<r<b, 0<θ<2pi)
the boundary condition is the netural boundary on (r=a) expressed as ...