Implicit Runge-Kutta based sparse identification of governing equations in biologically motivated systems.

Identifying governing equations in physical and biological systems from datasets remains a long-standing challenge across various scientific disciplines. Common methods like sparse identification of nonlinear dynamics (SINDy) often rely on precise derivative approximations, making them sensitive to data scarcity and noise. This study presents a novel data-driven framework by integrating high order implicit Runge-Kutta methods (IRKs) with the sparse identification, termed IRK-SINDy. The framework exhibits remarkable robustness to data scarcity and noise by relying on the A-stability of IRKs and consequently their fewer limitations on stepsize. Two methods for incorporating IRKs into sparse regression are introduced: one employs iterative schemes for numerically solving nonlinear algebraic system of equations, while the other utilizes deep neural networks to predict stage values of IRKs. The performance of IRK-SINDy is demonstrated through numerical experiments on synthetic data in benchmark problems with varied dynamical behaviors, including linear and nonlinear oscillators, the Lorenz system, and biologically relevant models like predator-prey dynamics, logistic growth, and the FitzHugh-Nagumo model. Results indicate that IRK-SINDy outperforms conventional SINDy and the RK4-SINDy framework, particularly under conditions of extreme data scarcity and noise, yielding interpretable and generalizable models.