Generalized inverses of differential algebraic equations and their discretization In this dissertation we present numerical methods for the computation of generalized solutions of over or underdetermined differential algebraic equations (DAEs). After an introdution in the theory of linear DAEs and the associated generalized solutions we present the following main results: In section 3.2 we show that the local (step wise) minimization of a BDF discretization of a linear DAE leads to an O(h) approximation of a certain generalized solution of the DAE. In section 3.3 it is shown that the global minimization of a linear DAE i.e. the least squares solution of the discretization leads to an O(h) approximation of the least squares solution of the DAE. Implementations of the methods presented here are given on the enclosed CD ROM. In section 4 of this dissertation the above results are verified by numerical tests.