Algebraic expressions in when conditions not parsed correctly

[jwharington@…]

Depending on the order of the conditional expression, when conditions don't function correctly in all cases.

Example code:

class bugtime
  discrete Real timeAtActivation;
  Boolean next;

  algorithm

    // this works
    when (time>0.1) then
      timeAtActivation := time;
      next := true;
    end when;

    // this works
    when next and (time>0.1+timeAtActivation) then
      print("time>0.1+timeAtActivation");
    end when;

    // this doesnt work
    when next and (time-timeAtActivation>0.2) then
      print("when time-timeAtActivation>0.2");
    end when;

    // this one does work
    if next and (time-timeAtActivation>0.3) then
      print("if time-timeAtActivation>0.3");
      next:= false;
    end if;

  annotation( experiment( StopTime=2, method='euler' ) );

end bugtime;

[Martin Sjölund]

Note that this model isn't valid (see #2105). Does it work correctly if you use elsewhen?

[jwharington@…]

Using elsewhen as you recommend, as shown below, doesn't even compile.

Error: Internal error Inverse Algorithm needs to be solved for {next,$whenCondition3,$whenCondition1,$whenCondition2,timeAtActivation} }}}


{{{
class bugtime
  discrete Real timeAtActivation;
  Boolean next;
algorithm
  when time > 0.1 then
    timeAtActivation := time;
    next := true;
  elsewhen next and time > 0.1 + timeAtActivation then
    print("time>0.1+timeAtActivation");
  elsewhen next and time - timeAtActivation > 0.2 then
    print("when time-timeAtActivation>0.2");
  end when;
end bugtime;
}}}

[Martin Sjölund]

The following works fine, so I guess the backend developers forgot some cases... when-equation (which should be recommended over when-statements) didn't work regardless.

class bugtime
  discrete Real timeAtActivation;
  Boolean next;
algorithm
  when time > 0.1 then
    timeAtActivation := time;
    next := true;
  elsewhen next and time > 0.1 + timeAtActivation then
    timeAtActivation := pre(timeAtActivation);
    next := pre(next);
    print("time>0.1+timeAtActivation");
  elsewhen next and time - timeAtActivation > 0.2 then
    timeAtActivation := pre(timeAtActivation);
    next := pre(next);
    print("when time-timeAtActivation>0.2");
  end when;
end bugtime;

[Lennart Ochel]

We have to increase our warnings/errors a lot.
I guess we can close this, since #2105 discusses the same.

[jwharington@…]

Sorry to re-open this, but the example sjoelund provides doesn't work correctly.

It does compile yes, but note that when it is run,
"when time-timeAtActivation>0.2" is not printed out. In other words, a simple rearranging of the time/timeAtActivation condition means the condition is or isn't caught.

Example

class bugtime
  discrete Real timeAtActivation;
  Boolean next;
algorithm
  when time > 0.1 then
    timeAtActivation := time;
    next := true;
  elsewhen next and time - timeAtActivation > 0.1 then
    timeAtActivation := pre(timeAtActivation);
    next := pre(next);
    print("this is never seen");
  end when;
end bugtime;

Can you see now?

• "time-timeAtActivation > 0.1" fails to be triggered
• "time > 0.1 + timeAtActivation" is correctly triggered

[jwharington@…]

Further to my previous re-opening, I don't believe it's a duplicate of #2105. Even if I'm doing something wrong in this example code, the problem in this particular case is to do with parsing or evaluation of when conditions, which is a different kind of problem to #2105.

And also, thank you very much everyone that you responded to the bug report so quickly!

[Willi Braun]

Your first model is correct, and as far as I see we have a bug in findZeroCrossings for algorithms.
I'll check it.

[Martin Sjölund]

Postponed until 1.9.1

[Willi Braun]

It seems to be fixed in the meanwhile.