A support case with the identification [CASE:4275098] was created.

While I noted some implementation problems regarding inner and outer in another context which have been acknowledged, I would like to get very general advice on how to reliably (= correctly?) make use of inner and outer declarations in Wolfram System Modeler.

I would like to provide three simple examples for a clarifying discussion.

Outer Declaration inside a subcomponent

The following example works fine: The inner variables x, y, z[3] are passed on towards the submodel using corresponding outer declarations and accordingly subX, subY, and subZ show correct values if we simulate MainModel.

package TestingInnerOuter_1
  model MainModel
    inner parameter Integer x = 1;
    inner parameter Real y = 2;
    inner Real z[3];
    Submodel submodel;
  equation
    z = ones(3);
  end MainModel;

  block Submodel
    outer parameter Integer x;
    outer parameter Real y;
    outer Real[3] z;
    output Real subX, subY;
    output Real[3] subZ;
  equation
    subX = x;
    subY = y;
    subZ = z;
  end Submodel;

 end TestingInnerOuter_1;

Simultaneous inner outer declaration inside a subcomponent

Now we simply add inner as a prefix to the outer declarations making them simultaneous inner outer declarations.

package TestingInnerOuter_2
  model MainModel
    inner parameter Integer x = 1;
    inner parameter Real y = 2;
    inner Real z[3];
    Submodel submodel;
  equation
    z = ones(3);
  end MainModel;

  block Submodel
    inner outer parameter Integer x;
    inner outer parameter Real y;
    inner outer Real[3] z;
    output Real subX, subY;
    output Real[3] subZ;
  equation
    subX = x;
    subY = y;
    subZ = z;
  end Submodel;

end TestingInnerOuter_2;

And now the MainModel will not run but give errors from compilation:

From this message we already get a "hunch" about what is going amiss. And indeed the following modified version of Submodel will work in the second example:

block Submodel
  inner outer parameter Integer x;
  inner outer parameter Real y;
  output Real subX, subY;
equation
  subX = x;
  subY = y;
end Submodel;

While the MainModel will now simulate, we note that the values for x and y are not passed on, instead we see that each has been given the default value of zero.

Simultaneous inner outer declaration inside a subcomponent with modifications

So, given the error message for z we finally look at a version where the submodel will modify the values for x and y.

package TestingInnerOuter_3
  model MainModel
    inner parameter Integer x = 1;
    inner parameter Real y = 2;
    inner Real z[3];
    Submodel submodel;
  equation
    z = ones(3);
  end MainModel;

  block Submodel
    inner outer parameter Integer x = -1;
    inner outer parameter Real y = -2;
    output Real subX, subY;
  equation
    subX = x;
    subY = y;
  end Submodel;

end TestingInnerOuter_3;

Interestingly, this works out for the parameters and subX and subY show the correct values (e.g. 1 and 2). But, what surprises me, is that 'submodl.x' and 'submodel.y' are reported to be -1 and -2 in the ModelCenter.

So to wrap it up, the following questions arise for me:

1. Why will an inner outer declaration not work out for continuous variables? What can be done?
2. Why are submodel.x and submodel.y not reported with the values according to the lookup to the inner values in a higher scope (e.g. the MainModel values)?

Update 1 (Warnings upon validation for inner outer )

I am a bit confused about the compiler messages I get for the following simple declaration of a parameter as inner outer:

model InnerOuter "Test of inner outer model"
  inner outer parameter Real myParameter = 1;
end InnerOuter;

Validating this model gives:

Those warnings do not really make sense, do they?

1. There is an inner declaration since the outer declaration is simultaneously an inner one.
2. The parameter myParameter has explicitly been given a start value of 1 which is not recognized somehow.

So another question is: What about those warnings - they do not seem correct. What is going on?

Update 2 (Internal error upon using inner outer in a subcomponent)

I am getting an internal error message validating a component that has a subcomponent with a parameter that is declared as inner outer. A minimal example for this is the following code:

package InnerOuterTest

    block HasInnerOuterParameter

       inner outer parameter Real k = 1;

    end HasInnerOuterParameter;

    block UsesComponentWithInnerOuterParameter

      HasInnerOuterParameter c;

    end UsesComponentWithInnerOuterParameter;

end InnerOuterTest;

Validation of the block UsesComponentWithInnerOuterParameter will give the following error message:

What is the reason for this message? How then should we have a parameter in a subcomponent that is simultaneously inner outer?

(Note: I tested the code given here (package InnerOuterTest) in OpenModelica and there it will validate without any errors)