 The theory behind our  algorithm is elementary and uses the concept of invariant subspaces for the Matlab {\tt eig} computed 'eigenvectors' of one flow matrix A (t_a) to find the coarsest simultaneous block structure for all flow matrices A (t_b).
<meaning-changed>  The theory behind our  algorithm is elementary and uses the concept of invariant subspaces for the Matlab {\tt eig} computed 'eigenvectors' of one flow matrix A (t_a) to find the coarsest simultaneous block structure for all flow matrices A (t_b).
 The theory behind our algorithm is elementary and uses the concept of invariant subspaces for the Matlab {\tt eig} computed 'eigenvectors' of one associated flow matrix B (t_a) to find the coarsest simultaneous block structure for all flow matrices A (t_b).