Evaluation of recursive functions during instantiation

[choeger]

Hi all,

this model:

model Fak

  function f 
    input Real x;
    output Real y = if x < 1.0 then 1.0 else x * f(x-1);
  end f;

  Real x;
  Real y = 24;
  equation
  
  f(x) = y;

end Fak;

crashes during instantiation with a stackoverflow. Just two thoughts:

• It seems like a bad idea in general to evaluate (recursive) functions at that time
• At least omc should catch the stackoverflow and discard the attempted optimization IMO.

[choeger]

Stacktrace

[sjoelund.se]

It is not trying to do any optimisation as far as I know. It for sure did not try to evaluate the function.
It is just some weird dependency analysis gone haywire if the output binding of the function is recursive. The following works fine in the frontend:

model Fak

  function f 
    input Real x;
    output Real y;
  algorithm
    y := if x < 1.0 then 1.0 else x * f(x-1);
  end f;

  Real x;
  Real y = 24;
  equation
  
  f(x) = y;

end Fak;

[sjoelund.se]

Postponed until 1.9.1

[sjoelund.se]

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).

[sjoelund.se]

Milestone changed to 1.9.3 since 1.9.2 was released.

[sjoelund.se]

Moved to new milestone 1.9.4

[sjoelund.se]

Milestone pushed to 1.9.5

[sjoelund.se]

Milestone renamed

[sjoelund.se]

Ticket retargeted after milestone closed

[sjoelund.se]

Milestone moved to 1.12.0 due to 1.11.0 already being released.

[casella]

The milestone of this ticket has been reassigned to "Future".

If you think the issue is still valid and relevant for you, please select milestone 1.13.0 for back-end, code generation and run-time issues, or 2.0.0 for front-end issues.

If you are aware that the problem is no longer present, please select the milestone corresponding to the version of OMC you used to check that, and set the status to "worksforme".

In both cases, a short informative comment would be welcome.

[perost]

Works fine with the new frontend.