A note on how to iterate adjustment

We study the elementary problem of adjusting a given parameter library by one measured response so that calculating the response with the adjusted library reproduces the measured value. We formulate the problem of the least-squares adjustment for non-linear responses, and offer a reasoned iteration scheme to solve it. A numerical example illustrates the success of the proposed procedure. Our scheme is identical to that suggested by Perey, and thus adds insight, offers justification, and also serves as a formal proof of the latter.