What is difference between "Direct form" and "Normal Direct form"? I was reading about filters implementations(structures) and found out both words "direct form"and "normal direct form" especially in proakis,2nd edition as shown highlighted in attached snapshot
The modifier normal is meant to distinguish the form from the transposed form. So there is a normal direct form I, a transposed direct form I, and similarly for the direct form II. As far as I know, this terminology is not universal, and I've only come across it in books (co-)written by Manolakis or Ingle.