==========================================================
 
      COMPUTE STABILITY OF THE LATTICE:
      AD,AF are the perturbation in the defocusing/defucusing
      elements those new values are given in QF,QD.
      STAB is a variable which can be -1,0,+1 according to
      the following table
 
       stab =  0  --> lattice stable
       stab = +1  --> |Tr(M_x)| > 2
       stab = -1  --> |Tr(M_y)| > 2
 
 
 ==========================================================
 
subroutine stability(AF,AD,qf,qd,stab)
 
COMMONS: 
common-initi.f
common-mml-lattice.f
 
SUBROUTINES USED:
  RESTOR
  CHANGEQUAD
  DYNMAP
 
micromap-index
Mon Jul 17 08:57:35 CEST 2017