Mon Sep 27 11:00:50 CEST 2010
Values and Transitions
This places the previous post in another light.
If you want to model a dynamical system (a system with internal
state), you need to have concepts of both state and transition.
For physical (Newtonian) dynamical systems this is very obvious: you
always need two state variables: position and velocity.
For discrete systems there is a clear analogy. To be able to detect
and compute in terms of value change, one needs to have access to the
_previous_ value, so there are also two state variables: current and
previous position, or current and difference.