The integral kernel in the Poisson integral, given by K(ψ) = 1/(2π) (1 - ( left bracketing bar z_0 right bracketing bar )^2)/( left bracketing bar z_0 - e^(i ψ) right bracketing bar )^2 for the open unit disk D(0, 1).

Dirichlet problem | harmonic function | mean-value property | Poisson integral