Perturbation Series

A perturbation series is a mathematical approach used to find an approximate solution to complex problems, particularly in physics and engineering. It starts with a simple problem that has a known solution and adds small changes or "perturbations" to it. By systematically calculating how these changes affect the solution, we can build a series of approximations. This method is useful when exact solutions are difficult to obtain, allowing scientists and engineers to analyze systems by breaking them down into manageable parts while still capturing essential features of the original problem.