COMPUTING CONSISTENT INITIAL CONDITIONS FOR DIFFERENTIAL-ALGEBRAIC EQUATIONS

To solve differential-algebraic equation systems (DAEs) successfully initial conditions must be consistent, i.e. they must satisfy the corresponding extended system of the DAEs. For index one DAEs they can be obtained by either taking an implicit Euler step or solving the extended system together with a feasible set of specifications. We present computational algorithms for determining consistent initial conditions based on either approach. In addition, a purely numerical algorithm reported recently for computing initial values for higher index DAEs is modified here to reduce the computational complexity by using structural information on the DAEs.