Download the Polymath ODE_Solver 15-day Trial
Now you can easily solve simultaneous ordinary differential in Excel with a selection of five state-of-art algorithms. The Runge-Kutta-Fehlberg (RKF45) is the default algorithm that is highly recommended for most problems. Even stiff problems can be solved with two different still algorithms.
Polymath Software has created an Excel Add-In for simultaneous ordinary differential equations that is extremely easy to use. It uses an interface that is similar to that of the 'Solver Add-in' or 'Goal Seek'

with a screen for advanced options

and always available HTML Help.

More details on the Polymath ODE_Solver are available.
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The ODE_Solver comes with the latest Polymath software, but this unique ODE_Solver is now available as just an Add-In for Excel users. Try a fully-functional 15 day trial before you purchase.
Download the Polymath ODE_Solver 15-day Trial