title: ETS multiplicative trend model written in state space form
body: <p>I have an ETS(M,Md,N) model and would like to write it in state space form:</p>
  
  <p>yt=w(x{t-1})+r(x{t-1})ɛt
  xt=f(x{t-1})+g(x{t-1})ɛt</p>
  
  <p>For additive trend, the state vector xt=(lt,bt)'. But I have no idea how to write the state vector xt for multiplicative trend.</p>
  
  <p>Can anyone help please:D</p>