释义 |
Green's Function--Poisson's EquationPoisson's Equation equation is
 | (1) |
where is often called a potential function and a density function, so the differential operator in this case is . As usual, we are looking for a Green's function such that
 | (2) |
But from Laplacian,
 | (3) |
so
 | (4) |
and the solution is
 | (5) |
Expanding in the Spherical Harmonics gives
 | (6) |
where and are Greater Than/Less Than Symbols. This expression simplifiesto
 | (7) |
where are Legendre Polynomials, and . Equations(6) and (7) give the addition theorem for Legendre Polynomials.
In Cylindrical Coordinates, the Green's function is much more complicated,
 | (8) |
where and are Modified Bessel Functions of the Firstand Second Kinds (Arfken 1985). References
Arfken, G. Mathematical Methods for Physicists, 3rd ed. Orlando, FL: Academic Press, pp. 485-486, 905, and 912, 1985. |