In this section, we build on the model developments reported in the preceding two sections by articulating the differential equations which provi de the basis for dynamical analysis. This applies both to 'comparative static' analyses, when the equations provide the foundations for analyses of stability, and to disequilibrium situations, when the differential equations have to be solved directly. First, in Section 5.3.2, we set up the equations for the retailing example and demonstrate the general principles involved. We show how to present equivalent equations in difference equation form in Section 5.3.3. In the next three subsections, we then sholt briefly how to apply the principles to the other models considered earlier: the residential model, the Lowry model and various disaggregated models respectively.