ABSTRACT
Many physical phenomena are characterized by linear partial differential equations. Such equations are attractive to study because (a) principles of superposition apply in the sense that linear combinations of component solutions can often be used to build more general solutions and (b) Þnite difference or Þnite element approximations lead to systems of linear equations amenable to solution by matrix methods. The accompanying table lists several frequently encountered equations and some applications. We only show one-or two-dimensional forms, although some of these equations have relevant applications in three dimensions.
