DINA, a digital analyzer for Laplace, poisson, diffusion, and wave equations

IN AN extremely large number of problems concerning the behavior of physical systems the associated equation consists of the Laplace equation Δ ² u = 0 (1) or one of its close relatives Poisson equation Δ ² u = ρ (2) Diffusion equation Δ ² u = κ δ u δ t (3) Wave equation Δ ² u = 1 v² δ ² u δ t² (4) For a given problem, equations 1 through 4 are not definitive as they stand, but require the specification of boundary and initial conditions peculiar to the problem at hand.