Long-time relative error analysis for linear ODEs with perturbed initial value

Abstract: We investigate the propagation of initial value perturbations along the solution of a linear ODE ( y'(t) = Ay(t) ). This propagation is analized using the relative error rather than the absolute error. Our focus is on the long-term behavior of this relative error, which differs significantly from that of the absolute error. Understanding this long-term behavior provides insights into the growth of the relative error over all times, not just at large times. Therefore, it represents a crucial and fundamental aspect of the conditioning of linear ODEs, with applications in, for example, non-normal dynamics. The author hopes that this paper will stimulate attention to the role of relative error in dynamic contexts.