A second-order linear elliptic 偏微分 equation that describes systems in a steady-state or equilibrium condition. It is written as [乳胶]nabla^2 u = 0[/latex] or [latex]Delta u = 0[/latex], where [latex]nabla^2[/latex] (or [latex]Delta[/latex]) is the Laplace operator. Solutions, called harmonic functions, are the smoothest possible functions and represent potentials in fields like electrostatics, gravitation, and fluid flow.
