Evaluating structural parameters to avoid circular parameter bindings

[Adrian Pop]

The model reported on the forum by Javier (jgb):
​http://www.openmodelica.org/index.php?option=com_agora&task=topic&id=438&Itemid=87
puts the back-end into an infinite loop and stack-overflow.

model MyModel 
  parameter Boolean bool = true; 
  parameter Real var0 = 10; 
  parameter Real var1 = if bool then var0 else var0/var2; 
  parameter Real var2 = if bool then var0/var1 else var0; 
end MyModel; 

model MyModelTest 
annotation(experiment(StartTime = 0.0, StopTime = 1.0, NumberOfIntervals=100, Tolerance = 1e-06)); 
  
  MyModel myModel(var0=1); 

end MyModelTest; 

[Lennart Ochel]

This seems to be worked by Willi in r10543.
Now, there is a nonlinear system generated to solve the parameters. This needs to be changed.
I guess bool needs to be evaluated during transformation to avoid cyclic dependencies in the parameter bindings.

[Lennart Ochel]

Should this get handled in the front end?

[Martin Sjölund]

I believe the back-end should solve this. It would need to if they were initial equations anyway.

[Lennart Ochel]

This is only about parameters with bindings and has nothing to do with initial equations.
I guess that all other structural parameters get evaluated in the front end. Hence, it sounds reasonable to me to evaluated these ones there as well.

[Adrian Pop]

Lennart, these are not structural parameters see #1227.

[Adrian Pop]

Actually, I'm wrong, bool is a structural parameter. See more here: ​m:#1320.
This model is illegal if we do not add an annotation(Evaluate=true) on bool.

[Lennart Ochel]

Okay. That does mean it is an back end issue, right? I can add a check to the back end, so that such parameter systems will generate a proper error message.

[Adrian Pop]

We could add a check either in the fron-end, in the middle-end or in the back-end.
If is easy for you to add a check do it.

[Martin Sjölund]

This ticket was not closed for 1.9.1, which has now been released. It was batch modified for milestone 1.9.2 (but maybe an empty milestone was more appropriate; feel free to change it).

[Martin Sjölund]

Milestone changed to 1.9.3 since 1.9.2 was released.

[Martin Sjölund]

Moved to new milestone 1.9.4

[Martin Sjölund]

Milestone pushed to 1.9.5

[Martin Sjölund]

Milestone renamed

[Martin Sjölund]

Ticket retargeted after milestone closed

[Patrick Täuber]

Since there is an error message for such cases now, we can close this one.