A Unifying Framework for Perturbative Exponential Factorizations

We propose a framework where Fer and Wilcox expansions for the solution of differential equations are derived from two particular choices initial transformation that seeds product expansion. In this scheme, intermediate can also be envisaged. Recurrence formulas developed. A new lower bound convergence expansion is provided, as well some applications results. particular, examples worked out up to high order approximation illustrate behavior