Comments on Grimble´s comments on Stein´s comments on rolloff of H/sup infinity / optimal controllers

In M.J. Grimble´s comments (see ibid., vol.35, p.762-5, 1990), the polynomial systems approach to H/sup infinity / is shown to have an advantage over the state-space approach in that improper weighting functions can be used, allowing one to obtain controllers that roll off at high frequencies. It is shown that the same controller can be found with the state-space approach using a simple problem reformulation.<>