[Wolfgang Zocher (980807.0850 MESZ)]

I don't undestand the upcoming differences concerning the SD

"paradigma" and classic control theory as used in PCT to simulate

the control of behavior.

What we are trying to do (in terms of SD or PCT) is to simulate

a continuous system (continuous in time in most systems we are

are looking at) on a digital computer. A continuous system is

described mathematically with ordinary differential equations (ODEs),

differential algebraic equations (DAEs) or partial differential

equations (PDEs). All we have to do is to formulate the mathematical

description of the system and to solve the equations

ODE, DAE and PDE are used to describe the dynamics of a system!

In former times (30 or 40 years ago) solving ODEs was done with

analog computer machinery: the advantage was that a continous

"problem" was solved on a continuous machine - the disadvantage was

the need for big machinery ... But this way of solving (in finding

an electronic analogon for any mechnical, chemical or biological

system) was very close to the physics of the real system.

All ODEs which describe the dynamics of a particular system were

solved using a circuitry of integrators and amplifiers and

special devices like delays etc. eventually.

ANY system dynamics in ANY sort of system existing in reality

(or in mind) which could be described in terms of differential

equations could be simulated on such computers, including all

sorts of control problems, since control systems are nothing but

dynamic systems which can be described in ODEs, DAEs and PDEs.

Today, we are using digital computers. These computers are NOT

continuous devices since all data represented on these machines

have to be digitized and we have to look for good algorithms to

make them behave like analogs.

All those simulators are nothing but ODE- or DAE-Solvers!

I can't see anything NEW in a new "SD-paradigma" ...

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Wolfgang Zocher

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email: zocher@rrzn.uni-hannover.de (office)

zocher@apollo.han.de (home)

www: http://www.unics.uni-hannover.de/rrzn/zocher

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