% three-level shifted discretization of signal fu in [-1,1] 

function [ud,IS]=mdiscr(fu,dis,m,my,mu)

                                     % m-2  alternative discretizations
  IS=ones(mu,my)/mu;                 % the uniform ideal probability of ud 
  ul=-1;                             % lower bound of fu
  uu=1;                              % upper bound of fu
  ur=(uu-ul)/m;                      % increment of fu
  u1=ul+dis*ur;                      % lower bound of the narrow
                                     % band of dis-th convertor
  u2=ul+(dis+1)*ur;                  % upper bound of the narrow
                                     % band of dis-th convertor
  if fu<=u1  
     ud=1;                           % discretized signal
  elseif fu<=u2
    ud=2;
  else 
    ud=3;
  end