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Avoid StateSpaceModel SystemsModelDelay time delay problem in MMA 10.0.2.0?

Posted 1 year ago
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hi, I was trying to run the example in SystemsModelDelay->Basic Examples: "A time-delay state-space model created from delay differential equations:"

In[1]:= StateSpaceModel[{x'[t] == x[t] - 2 x[t - T] + u[t]},
 {x[t]}, {u[t]}, {3 x[t - T]}, t]

And I'm getting errors preventing evaluation (see below). My platform is Mac OSX x86 (32-bit, 64 bit kernel) and the Version Number is 10.0.2.0. I've tried running similar equations and get similar errors. Is there a bug in this release, and how can I upgrade/fix it?

During evaluation of In[1]:= Set::shape: Lists {Control`RecastDEquationsDump`additionalStateEqns,Control`RecastDEquationsDump`outputsNew,Control`RecastDEquationsDump`states} and Control`RecastDEquationsDump`accommodateOutputDynamics[If[-2 T==0,Continuous,DelayedContinuous],t,{},{u},t] are not the same shape. >>

During evaluation of In[1]:= $RecursionLimit::reclim: Recursion depth of 1024 exceeded. >>

During evaluation of In[1]:= $RecursionLimit::reclim: Recursion depth of 1024 exceeded. >>

During evaluation of In[1]:= Set::shape: Lists {Control`RecastDEquationsDump`inputsNew,Control`RecastDEquationsDump`controlDTerms} and Control`RecastDEquationsDump`siftedControlTerms[If[-2 T==0,Continuous,DelayedContinuous],{u},{},t] are not the same shape. >>

During evaluation of In[1]:= Flatten::normal: Nonatomic expression expected at position 1 in Flatten[0]. >>

During evaluation of In[1]:= StateSpaceModel::invrlzn: Cannot construct a state-space realization for the system of equations {(x^\[Prime])[t]==u[t]+x[t]-2 x[t-T]} with variables {{x[t],0}}, inputs {{u[t],0}}, and outputs {3 x[t-T]}. >>

Out[1]= StateSpaceModel[{Derivative[1][x][t] == 
   u[t] + x[t] - 2 x[t - T]}, {x[t]}, {u[t]}, {3 x[t - T]}, t]
2 Replies

This appears to be an old issue which was fixed sometime around version 10.3.

What you should do depends on how you get your license. If your license is from a university or a company, I would contact whoever is in charge of software purchasing or maintaining the license. They probably have an answer for you.

If this is a personal license, I would contact Wolfram Technical Support by email (support@wolfram.com) asking if there is a workaround that can be done for the problem.

Posted 1 year ago

Great, thank you. I will see if I can get upgraded to 10.3+.

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