Homotopy Analysis Method (or Homotopy Perturbation Method)?? How effective is this Homotopy Analysis Method (HAM) in solving coupled non-linear PDE? I see some papers, but they seem to be cross-referencing a small group of people most of the time. This sounds strange for a method that is so generic and so powerful (and has been around since 1992), as those papers all say. Homotopy Perturbation Method (HPM) is a recent variant of HAM. But this also seems to suffer from the same strange behaviors as HAM's papers.