 equation
          H                    2      H
     op(A) *X + X*op(A) = scale *op(B) *op(B),                   (3)

  or the discrete-time Lyapunov equation
          H                    2      H
     op(A) *X*op(A) - X = scale *op(B) *op(B),                   (4)

  provided, for equation (3), the given matrix A is replaced by -A,
  or, for equation (4), the given matrices A and B are replaced by
  inv(A) and B*inv(A), if TRANS = 'N' (or inv(A)*B, if TRANS = 'C'),
  respectively. Although the inversio