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			trunk	fixed		Willi Braun Jens Frenkel Lennart Ochel Willi Braun