Using analytical equations to represent nonlinear relationships

Table functions, also referred to as graphical provide a powerful and user-friendly way represent nonlinear relationships between variables in system dynamics (SD) models. However, many cases modelers may benefit from using analytical equations for model sensitivity testing communicating with researchers other fields disciplines. We propose six that can be used of the commonly formulated table functions SD Specifically, this article provides guidance on generalized logistic function, exponential modified quadratic logarithmic function power replace existing functions. Importantly, we present version each equation includes an interior reference point. demonstrate how apply these models by replacing original World Dynamics model. Python script help implement our recommended procedure incorporating into Vensim macro equation. © 2022 The Authors. System Review published John Wiley & Sons Ltd behalf Society.