model including two SpringDamper blocks leads to compiler error

[Peter Junglas]

The attached model DamperBug1 terminates with the following error:

Simulation process exited with code 253

Changing one of the SpringDamper blocks to a Spring works (cf. example DamperBug3).

[Martin Sjölund]

You should have gotten more messages:

./DamperBug1 
stdout            | warning | Failed to solve linear system of equations (no. 61) at time 0.000000, system is singular for U[5, 5].
stdout            | warning | Failed to solve linear system of equations (no. 62) at time 0.000000, system is singular for U[5, 5].
stdout            | warning | Failed to solve linear system of equations (no. 61) at time 0.002000, system is singular for U[5, 5].
stdout            | warning | Failed to solve linear system of equations (no. 62) at time 0.002000, system is singular for U[5, 5].
stdout            | info    | model terminate | linear system solver failed. | Simulation terminated at time 0.002

61 is the linear system that defines:
inertia1.w, der(idealrollingwheel1.flangeR.phi), mass1.v, der(idealrollingwheel2.flangeR.phi)

62 is the linear system that defines:
idealrollingwheel2.flangeR.phi, inertia1.phi, idealrollingwheel1.flangeR.phi, idealrollingwheel1.flangeT.s

[Peter Junglas]

Yes, I see these messages (at least with the current version, updating daily). But they make no sense, since structurally the two examples are identical. DamperBug3 works, as it should - and there is no reason for it to be structurally singular.

[Martin Sjölund]

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).

[Martin Sjölund]

Milestone changed to 1.9.3 since 1.9.2 was released.

[Martin Sjölund]

Moved to new milestone 1.9.4

[Martin Sjölund]

Milestone pushed to 1.9.5

[Martin Sjölund]

Milestone renamed

[Martin Sjölund]

Ticket retargeted after milestone closed

[Martin Sjölund]

Milestone moved to 1.12.0 due to 1.11.0 already being released.

[Francesco 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.

[Peter Junglas]

The model still doesn't work, the error message in 1.12.0 is

...
LOG_LS | warning | <p>Matrix singular!</p>
LOG_LS | warning | <p>under-determined linear system not solvable!</p>
stdout | warning | <p>Error solving linear system of equations (no. 88) at time 6.977000.</p>
stdout | warning | <p>Solving linear system 88 fails at time 6.977. For more information use -lv LOG_LS.</p>
...

The generated results are completely wrong!

The model is not singular at all, it is actually quite simple. I checked it by reducing the equations manually, which leads to the simple ODE system that a mechanical engineer would write down immediately. The example DamperBug3 works, though it is structurally identical. And DamperBug1 works without any problems in Dymola.

This really is a sign of a flaw in the backend, probably in the equation reduction system, and should be solved as soon as possible.

[Francesco Casella]

Rescheduled to 1.14.0 after 1.13.0 releasee

[Francesco Casella]

@Karim, I guess you should have a look at this, looks quite fishy

[Karim Adbdelhak]

I have looked a bit into DamperBug1 and it seems that in C++ in works just fine. It looks like that there is something wrong with the linear solvers, maybe a problem from code-generation. I will try to figure out what C++ does differently.

[Francesco Casella]

Releasing 1.14.0 which is stable and has many improvements w.r.t. 1.13.2. This issue is rescheduled to 1.16.0

[Francesco Casella]

Retargeted to 1.17.0 after 1.16.0 release

[Francesco Casella]

Retargeted to 1.18.0 because of 1.17.0 timed release.

[Francesco Casella]

Ticket retargeted after milestone closed