Conditional Components in Modelica

Question

I want with conditional expressions reduce large general models with over 300000 equations so that only a relevant part remains. To illustrate the problem I have the following minimal model:

model Test
  parameter Boolean level1=true;
  parameter Boolean level2=false;
  Integer x=1 if level1;
  Integer y=2 if level2;
  Integer z;
equation
  if level1 and level2 then
    z = x+y;
  elseif level1 then
    z = x;
  elseif level2 then
    z = y;
  else
    z=0;
  end if;
end Test;

This model does not work in Dymola, with the error message:

Undeclared variables: y since the declaration of y was conditionally removed

In OpenModelica the model works. So my question is, is this Model Modelica compliant? In the Modelica 3.4 specification section 4.4.5 I did not find anything that would invalidate this model.

Thanks for the help.

score 5 · Accepted Answer · answered Feb 07 '18 at 17:01

No, since y and x are declared conditional and 4.4.5 includes the statement "A component declared with a condition-attribute can only be modified and/or used in connections".

There is no special rule that they can be removed from branches of if-statements.

Conditional Components in Modelica

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