id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
6200	Issues with redundant initial conditions in Buildings model?	Francesco Casella	Karim Adbdelhak	"Please check [https://libraries.openmodelica.org/branches/master/Buildings_7.0.0/files/Buildings_7.0.0_Buildings.Experimental.DistrictHeatingCooling.Validation.HeatingCoolingHotWaterSmall.err Buildings.Experimental.DistrictHeatingCooling.Validation.HeatingCoolingHotWaterSmall]. The backend fails with
{{{
Warning: It was not possible to determine if the initialization problem is consistent, because of not evaluable parameters/start values during compile time: pla.coo.con.vol.dynBal.medium.p = pla.coo.con.vol.dynBal.p_start (pla.sinCoo.p = pla.coo.con.vol.dynBal.p_start)
Warning: It was not possible to determine if the initialization problem is consistent, because of not evaluable parameters/start values during compile time: pla.hea.eva.vol.dynBal.medium.p = pla.hea.eva.vol.dynBal.p_start (pla.sinHea.p = pla.hea.eva.vol.dynBal.p_start)
Notification: Performance of analyzeInitialSystem (initialization): time 0.195/7.507, allocations: 29.7 MB / 2.141 GB, free: 0.611 GB / 1.292 GB
Notification: Performance of solveInitialSystemEqSystem (initialization): time 9.535e-05/7.507, allocations: 24 kB / 2.141 GB, free: 0.611 GB / 1.292 GB
Error: Internal error IndexReduction.pantelidesIndexReduction failed! System is structurally singular and cannot be handled because the number of unassigned equations is larger than the number of states. Use -d=bltdump to get more information.
Error: No system for the symbolic initialization was generated
}}}
I guess the problem is that there initial equations made redundant by state constraints, and the backend can't deal with them because they are parameter-dependent.

In this case, I would suggest the backend to make those parameters structural and constant-evaluate them. I tried to do that by turning on the evaluate all parameters option, but unfortunately this doesn't work because the model uses external functions and the frontend cannot evaluate them."	defect	new	critical	1.18.0	Backend				Andreas Heuermann