On Lyapunov scaling factors of real symmetric matrices
Daniel Hershkowitz, Hans Schneider · Linear and Multilinear Algebra · 1988
A necessary and sufficient condition for the identity matrix to be the unique Lyapunov scaling factor of a given real symmetric matrix A is given. This uniqueness is shown to be equivalent to the uniqueness of the identity matrix as a scaling D for which the kernels of A and AD are identical.