The discussion of mathematics of control in the “Perceptual Control Theory” article in Wikipedia is based on the discussion in the 2011 paper by Powers et al..
The discussion in Rick’s new methods book (I don’t have a link) frames it somewhat differently.
We need someone quite competent in the math to make sure the article is correct.
There is also a flag on that section calling out visual confusion between Tau and T (between τ and T) which are are difficult to distinguish in the rendering of the HTML. An editor asked us to clean that up.