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This question is about how Dymola will assign value reference(VR) to its variables(esp. derivatives). I understand that it is kinda like a secret about how VRs are assigned but any help would be appreciated.

For example, I have an exported model from Dymola, and the VRs for derivative variables look like this

587202618   der_1
587202619   der_2
587202620   der_3
*33554490    der_4
587202622   der_5
587202623   der_6
**318767166   der_7
**318767167   der_8

It could be found that from der_1 to der_6 the VRs are consistent, except from der_4. And it is not consistent because this der_4 is also a state, so this VR is the same as its state VR. So I understand this part well.

My question is about the last two VRs. They suddenly become inconsistent and they are not state variables. I don't understand why.

I look into those variables in the model, I found that those derivatives seem to have forms like this

der_7 = func(der_1, der_3, ..);
der_8 = func(der_1, der_3, ..);

So I believe Dymola has a reason to assign those variables different VRs. (Algebraic loops?)

Do those derivatives have any specific names? And how those derivatives are treated in Dymola?

Thanks

Hang Yu
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  • I think it would be useful if you included why you want to know the VR for different derivatives. It may be that there are other ways to address your more fundamental issue. – Michael Tiller Jun 27 '14 at 12:37
  • Thanks for your reply Micheal, I was trying to hook up an optimizer to drive the model to steady state, but state_7 and state_8 will not converge for some reason that I have not figured out, then I found their VRs are not consistent. Also, I asked this question out of some kinda of curiosity. – Hang Yu Jun 27 '14 at 12:48
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    If you want to understand what makes them different, look at the .mof files. That will explain how they are solved. I don't have access to Dymola on this computer, but somewhere in the translation settings there is an option. There are two .mof files. You probably want `dsmodel.mof`. Digging through that should give you a lot more insight than just looking at VR numbers. – Michael Tiller Jun 27 '14 at 20:48
  • Thanks Micheal, I will take a look at the dsmodel.mof file, thanks a lot for your help. – Hang Yu Jun 30 '14 at 12:43

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