This very simple circuit fails

[massimo ceraolo]

I came across in a circuit that fails to simulate with OM r23316.
I've simplified it as much as possible.
The final version, that I enclose (test.mo), contains a very few components and does simulate.
It should be ok and simulates well in Dymola.
Any further simplification produces a circuit that OM can simulate.

Since it is rather simple, maybe by analysing this it is possible to find some OM weakness that can be fixed.

Error message:

[:0:0-0:0] Error: Internal error Transformation Module sort components failed!
[c:/dev/OpenModelica/Compiler/BackEnd/BackendDAETransform.mo:114:7-115:62] Error: Internal error function strongComponentsScalar failed

• sorting equations (strongComponents) failed

[c:/dev/OpenModelica/Compiler/BackEnd/BackendDAETransform.mo:468:9-468:92] Error: Internal error function analyseStrongComponentBlock failed
[:0:0-0:0] Error: When solving linear system
1 : (-Lf2.i) - rDn.i - dcCap.i = 0.0
2 : rDn.i + Lf.i - rUp.i = 0.0
3 : dcCap.i + rUp.i - Lf1.i = 0.0
[

-1.0 , 0.0 , -1.0 ;
0.0 , -1.0 , 1.0 ;
1.0 , 1.0 , 0.0

]

*

[

dcCap.i ;
rUp.i ;
rDn.i

]

=

[

Lf2.i ;
-Lf.i ;
Lf1.i

]

U(3,3) = 0.0, which means system is singular for variable rDn.i.