<math> \nabla^2 T(\mathbf{r}) = 0 </math>
 Under the static assumptions, Maxwell's The steady-state heat diffusion equations reduce to are elliptic partial differential equations known as the Poisson and Laplace equations. These equations can be solved analytically only for a few canonical geometries with very simple boundary conditions. For most practical and realistic problems, you need to utilize a numerical technique and seek a computer solution. The Poisson and Laplace equations can be solved numerically using the finite difference (FD) method.
== Thermal Boundary Conditions ==