# Green's function for the Laplace operator $\Delta$ in a rectangle (or square)?

What I'm looking for is an explicit form of the Green's function $G$ for the Laplace operator $\Delta$ in a rectangular (or square) domain $D\subset\mathbb R^2$, e.g. $D=[0,1]\times[0,1]$. Namely, I'm looking for the solution $G:D\times D\rightarrow \mathbb R$ to the following PDE: $$\begin{cases} \Delta_x G(x,z) = -\delta_z(x) & \text{for }x\in D \\ G(x,z) = 0 & \text{for }x\in\partial D \end{cases}$$ where $\Delta_x$ is the laplacian with respect to the first variable $x\in\mathbb R^2$ and $\delta_z(x)$ is the Dirac delta ($\delta_z(x)=1$ if $x=z$ and $0$ otherwise).

I need it in order to provide a (hopefully simple) example to a problem I am studying, which involves the Green's function. I don't know where to start and I am not very familiar with second order PDEs; any solution or hint is highly appreciated, thanks in advance!

-
Maybe this is what you want: sciencedirect.com/science/article/pii/S0955799706000683 – Marco Lombardi Feb 28 '13 at 10:13
@MarcoLombardi Grazie mille! Thank you very much, I am reading it right now. Why don't you post your comment as an answer so that I can close the question? – AndreasT Feb 28 '13 at 10:36