Stiff systems

Implicit continuous variable-step solvers are especially suited for stiff systems. In Simulink, you can choose from: ode15s, ode23s, ode23t or ode23tb.

• Start by using ode15s.

• At crude error tolerances, try using ode23s or ode23tb.

• If your model is only moderately stiff or to prevent numerical damping, try using ode23t.

Note

Try to avoid using methods that are not designed for stiff systems on intervals where solutions change slowly. Indeed, such methods use time steps small enough to capture the fastest possible change whereas for stiff problems, the solution of interest changes on a much longer time scale.