
investigations. The method is not foolproof and should be repeated if the simulation conditions
change as a result of significant changes in the system inputs or initial conditions. We will have
more to say about how to select the integration step size in Chapters 6 and 8 when we investigate
the subject of truncation errors and dynamic errors.
3.5.2 NONLINEAR FIRST-O RDER SYSTEMS
We now turn our attention to nonlinear first-order systems, that is, systems in which the state
derivative f (x, u) is a nonlinear function of the state x. The implicit numerical integrators produce
implicit difference equations for updating the state.
Consider a first-order