id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
4168	DAE index reduction in clocked partitions	Rüdiger Franke	Lennart Ochel	"Clocked partitions may contain high index DAEs, for instance when basing a discrete-time controller on an inverse continuous-time model, see:
   Modelica_Synchronous.Examples.Systems.ControlledMixingUnit
   Modelica_Synchronous.Examples.Systems.EngineThrottleControl
OpenModelica produces wrong results for such models.

OpenModelica currently discretizes differential equations by replacing `der(x)` with `(x - previous(x))/interval()` during clock partitioning (Euler).

OpenModelica should reduce the DAE index inside a clocked partition prior to the discretization.

See the failing test `synch.mos` (ControlledMixingUnit)
https://github.com/OpenModelica/OpenModelica-testsuite/commit/ee09ab4b8551ce22514b4315cb04b88fdf2843ed"	defect	new	high		Backend