MathGroup Archive 1999

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System Modelling with Mathematica

  • To: mathgroup at smc.vnet.net
  • Subject: [mg18784] System Modelling with Mathematica
  • From: com3 at ix.netcom.com (Steve Comstock)
  • Date: Tue, 20 Jul 1999 01:33:36 -0400
  • Organization: Netcom
  • Sender: owner-wri-mathgroup at wolfram.com

Does anyone know where one could find sample notebooks that can aid in
modelling 2 input , 1 output systems ?

We have time-domain test measurements (ASCII files) of the inputs and
the outputs at roughly equal time points that capture the steady state
as well as transient behaivor of a complex system. The "output" from
this system is actually the mathematical average of several "true"
outputs from the hardware under test and thus cannot be represented by
the first principles of the underlying physics to the degree of
accuracy needed.

We were thinking along the lines of some sort of least squares
minimization of the error approach which would solve for the
coefficients of the underlying function. The problem is that we aren't
sure what this function should look like. Perhaps Mathematica could be
setup to search for this function ?

Another system has a "System Identification Toolbox" that tries to solve this
kind of problem (not sure of how or if it works). Has something
similar in Mathematica been attempted ?

A more specific newsgroup or website on this topic would be welcomed
as well.

Not interested at this time in neural networks, general order
polynomials or other "purely mathematical" approaches but an
approach (if possible) that is more "systems based" that has knowledge
of how "well-behaved" systems respond to changing inputs.

We have Mathematica version 3.0. 

Thanks in advance . . .

Steve.




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