C     Invert g(.,.,.,.) to calculate z(t,.) 

C



      z(t,1) = alpha(1) * psi(t,1)  

      z(t,2) = alpha(1) * psi(t,2)  



C     Calculate the phi to be predicted

C     i.e. the expression inside the condition5al expectation that

C     we try to predict by psi

      if (t.lt.3) goto 4

      cold = c

   4  continue

   

      c = theta(t,1) + theta(t,2)

      

      if (t.lt.140) goto 10



      do 8 j=1, 2

   8   phi(t-1,j) = ((c/cold)**alpha(2))*(z(t,j) + theta(t,j))

                 

  10  continue