A rather general sufficient condition is given for the stability of linear systems that may be used to extend the limited state LQR problem, or Lyapunov\´s stability criterion. Note: Let

and

then

is called the control

is called the influence

is called the output and y
ois called the synthetic output where

. If we choose

as a control we get the autonomous linear system

where

. We may not choose the control to be a function of the synthetic output, nor may we in any way choose the influence.