Enhance possibilities to re-simulate

[massimo ceraolo]

Consider the following model

model Test2 
  import Modelica.Constants.pi;
  parameter Real Ipm;
  parameter Real varPar (fixed=false);
initial equation
  if Ipm>1.0 then
    varPar=pi/2;
  else
    varPar=asin(Ipm);
  end if;
equation
end Test2;

This model does not run under Dymola, which issues the following error message:

The following parameter doesn't have any value: Ipm

It is instead brilliantly run by OpenModelica, which uses the available start value (start=0.0) for Ipm, and also allows changing Ipm and re-simulating.
I.e., OpenModelica is able to run this model without taking Ipm as a structural parameter.

If I change the row

  parameter Real Ipm;

into

  parameter Real Ipm=1.5;

OM runs it, but Ipm has become unchangeable.
I think that it is very good that OM succeeds in keeping Ipm non-structural, even though it is used in an if-clause condition. But since it is able to do so, why not allowing this also when an explicit value is given to the parameter?

I made my tests with OMEdit connected to OMC v1.14.0-dev-234-g5ef43cce8 (64-bit), under Windows.

I marked this ticket as "enhancement", but probably it requires just a very small change in what OM already does.