Following comments here and here I have added two examples to the ODE Solver spreadsheet showing use of the ODE function to solve systems of differential equations with two or more coupled equations. The new version (including full open source code) may be downloaded from ODESolver.zip.
The first new example is the system of equations for the Lorenz-Attractor. As for the examples given previously, it is necessary to create a short VBA function to evaluate each of the differential equations for given values of the variables and coefficients. This function is called by the Alglib ODE solver (included with the download file) to solve the system of equations for any specified series of steps:
Results for coefficients as used by Lorenz:
The second example is the classic predator-prey system, where increasing prey numbers are limited by increasing numbers of predators, until the prey animals go into a rapid decline, followed by decline in predators, until prey numbers start to increase again. This example was taken from the document on solution of differential equations at the XNumbers site: ODE Tutorial