Introduction

DDESolve is designed to allow numerical solution of systems of ordinary and delay differential equations, which may have state variable discontinuities (switches). To use it you must have the Apple Developer tools installed on your machine. To solve a set of equations you must edit a template C file to specify the model. This is then compiled and linked to the numerical and graphical routines which will solve the model and display the results. DDESolve was originally designed to solve population dynamic models.

DDESolve's advantages are that the numerical analysis is particularly carefully done with respect to solution of delay differential equations, it is quite fast relative to other packages (using efficient adaptive timestepping), its graphics use only the Cocoa API so you don't need extra toolboxes or add-ins to use it and it's open source. Switches are treated in a less rigorous manner (but I don't know of a package that does any better). DDESolve's disadvantages are that it doesn't do anything except solve your equations, it does little to check that the user's code is error free, and some of the Cocoa programming is inelegant (it was one of my first attempts at Cocoa programming).

This manual is not designed to be comprehensive, but is designed to explain how to code up a model and how to compile and link it once you have done so. Under the assumption that most users will start with one of the supplied example models, I will first describe compiling and linking. I will then explain how models are specified in detail and provide examples of how to do so. Finally I will briefly discuss the algorithms used.

The package is provided on condition that the following be accepted:

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