Derivative and proportional state feedback for linear descriptor systems with variable coefficients

We study linear descriptor systems with rectangular variable coefficient matrices. Using local and global equivalence transformations, we introduce normal and condensed forms and get sets of characteristic quantities. These quantities allow us to decide whether a linear descriptor system with variable coefficients is regularizable by derivative and/or proportional state feedback or not. Regularizable by feedback means for us that there exists a feedback which makes the closed loop system uniquely solvable for every consistent initial vector. (C) Elsevier Science Inc., 1997.