low-rank approximation

In this paper, we present a new approach for solving large-scale differential Lyapunov equations.  The proposed approach is based on projection of the initial problem onto an extended block Krylov subspace by using  extended nonsymmetric block Lanczos algorithm then, we get a low-dimensional differential Lyapunov matrix equation.  The latter differential matrix equation is solved by the Backward Differentiation Formula method (BDF) or Rosenbrock method (ROS), the obtained solution allows to build a low-rank approximate solution of the original problem.  Moreover, we also give some theoretic