`--generateSymbolicLinearization` causes error for some models

[ondras12345]

Description

Current implementation of ModelicaSystem sets --generateSymbolicLinearization in __init__, regardless of whether the user actually wants to perform linearization. This causes an error for some models, e.g. this one:

model.mo:

model MyModel
  Modelica.Clocked.RealSignals.Sampler.SampleClocked sample1 annotation(
    Placement(transformation(origin = {-40, 40}, extent = {{-6, -6}, {6, 6}})));
  Modelica.Clocked.RealSignals.Sampler.Hold hold1 annotation(
    Placement(transformation(origin = {20, 40}, extent = {{-6, -6}, {6, 6}})));
  Modelica.Clocked.ClockSignals.Clocks.PeriodicRealClock periodicClock1(period = 0.1)  annotation(
    Placement(transformation(origin = {-80, 0}, extent = {{-6, -6}, {6, 6}})));
  Modelica.Blocks.Interfaces.RealInput u annotation(
    Placement(transformation(origin = {-86, 40}, extent = {{-20, -20}, {20, 20}}), iconTransformation(origin = {-86, 30}, extent = {{-20, -20}, {20, 20}})));
  Modelica.Clocked.RealSignals.Periodic.TransferFunction transferFunction(b = {1}, a = {1, -1})  annotation(
    Placement(transformation(origin = {-12, 40}, extent = {{-10, -10}, {10, 10}})));
  Modelica.Blocks.Interfaces.RealOutput y annotation(
    Placement(transformation(origin = {60, 40}, extent = {{-10, -10}, {10, 10}}), iconTransformation(origin = {60, 40}, extent = {{-10, -10}, {10, 10}})));
equation
  connect(periodicClock1.y, sample1.clock) annotation(
    Line(points = {{-74, 0}, {-40, 0}, {-40, 32}}, color = {175, 175, 175}));
  connect(u, sample1.u) annotation(
    Line(points = {{-86, 40}, {-48, 40}}, color = {0, 0, 127}));
  connect(sample1.y, transferFunction.u) annotation(
    Line(points = {{-34, 40}, {-24, 40}}, color = {0, 0, 127}));
  connect(transferFunction.y, hold1.u) annotation(
    Line(points = {{0, 40}, {12, 40}}, color = {0, 0, 127}));
  connect(y, hold1.y) annotation(
    Line(points = {{60, 40}, {26, 40}}, color = {0, 0, 127}));

annotation(
    uses(Modelica(version = "4.0.0")));
end MyModel;

with demo.py:

#!/usr/bin/env python3
from OMPython import ModelicaSystem

# note the raiseerrors=True
mod = ModelicaSystem("model.mo", "MyModel", ["Modelica"], raiseerrors=True)
# this should be enough to demonstrate the error

Running demo.py results in the following exception:

Traceback (most recent call last):
  File "/home/ondra/tmp/lin-demo/./demo.py", line 4, in <module>
    mod = ModelicaSystem("model.mo", "MyModel", ["Modelica"], raiseerrors=True)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ondra/source/repos/OMPython/OMPython/ModelicaSystem.py", line 228, in __init__
    self.buildModel(variableFilter)
  File "/home/ondra/source/repos/OMPython/OMPython/ModelicaSystem.py", line 352, in buildModel
    self._check_error()
  File "/home/ondra/source/repos/OMPython/OMPython/ModelicaSystem.py", line 332, in _check_error
    self._raise_error(errstr=errstr)
  File "/home/ondra/source/repos/OMPython/OMPython/ModelicaSystem.py", line 336, in _raise_error
    raise ModelicaSystemError(f"OM error: {errstr}")
OMPython.ModelicaSystem.ModelicaSystemError: OM error: [/var/lib/jenkins/ws/LINUX_BUILDS/tmp.build/openmodelica-1.25.0/OMCompiler/Compiler/BackEnd/Differentiate.mo:268:5-268:157:writable] Error: Derivative of expression "transferFunction.x1 = (transferFunction.u - transferFunction.a[2] * previous(transferFunction.x[1])) / transferFunction.a[1]" w.r.t. "dummyVarD" is non-existent.
Error: Internal error SymbolicJacobian.deriveAll failed
[/var/lib/jenkins/ws/LINUX_BUILDS/tmp.build/openmodelica-1.25.0/OMCompiler/Compiler/BackEnd/SymbolicJacobian.mo:2474:7-2474:74:writable] Error: Internal error SymbolicJacobian.generateSymbolicJacobian failed
[/var/lib/jenkins/ws/LINUX_BUILDS/tmp.build/openmodelica-1.25.0/OMCompiler/Compiler/BackEnd/SymbolicJacobian.mo:2265:9-2265:79:writable] Error: Internal error function createJacobian failed

Ideally, it should be possible to simulate this model while keeping raiseerrors=True.

Version and OS

• Python Version: 3.12.3
• OMPython Version: 0b63a2b
• OpenModelica Version: 1.25.0
• OS: Ubuntu 24.04.2 LTS

[arun3688]

@ondras12345 that is true, current ModelicaSystem sets --generateSymbolicLinearization, it is done to improve the performance of linearization to avoid recompilation, eventhough user does not want to perform linearization, but then there are cases where users wants to perform the linearization in some kind of simulation loop and that takes too much time to compile the model. So one solution should would be to set the --generateSymbolicLinearization using some args in ModelicaSystem( linearization = true), by default the argument can be linearization = false , but in general it should work may be it is a bug in the backend
@adeas31 what do you think