ABSTRACT
All physical systems are distributed in space, so it is natural to seek models that also are distributed in space. A distributed-parameter model has at least one spatial independent variable, and possibly two or three, for example the Cartesian coordinates x, y and z. Dynamic models also have time as an additional independent variable. The lumped dynamic models considered exclusively thus far have only time as their one independent variable, leading to ordinary differential equations. The presence of two or more independent variables requires that distributed parameter models for dynamic systems be represented mathematically by partial differential equations.
