Quantitative models based on nonlinear dynamics and complex systems are frequently used in various areas ranging from climate research to neuroscience to power networks. Such systems, including biological organisms, consist of interacting units with oscillatory elements. For example, several measurable quantities in living systems such as blood flow, respiration and brain activity are oscillatory and their frequencies and amplitudes vary in time, often in an almost deterministic and nearly periodic manner. It’s crucial to understand these time-variable oscillations in order to develop applications in fields like physiology and medicine.