id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
1455	initial_residual() equations are created with removed Vars -> initialization problems	Willi Braun	Willi Braun	"The initial_residual() equations  are created in some cases with already removed equations. \\This can produce some really strange errors, while the simulation. 

One of them ist the following: 
{{{
""Error in initialization. Solver iterated 50000 times without finding a solution"".
}}}

Or in some case the following occurs: 
{{{
Error solving linear system of equations (no. 2458) at time 0.000000, system is singular.
Error solving linear system of equations (no. 2458) at time 0.000000, system is singular.
 DASSL-- TOUT (=R1) TOO CLOSE TO T (=R2) TO START INTEGRATION
      In above,  R1 =   .5000000000000E+00   R2 =   .0000000000000E+00
DDASRT: The code has encountered trouble from which it cannot recover.
}}}

The Dassl message especially is really quite strange. 

I think we need a restructure of the BackendDAE.DAE record to split the Vars not only in Known and Unknown Variables. More in removedVars, states, parameters, free parameters and maybe some more. "	defect	closed	blocker		Backend	trunk	fixed		Willi Braun Frenkel TUD Lennart Ochel