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

function [yd,IS]=mdiscry(fy,dis,m,my,mu,Ify)

  sma=0.01;
  uni=ones(1,my*mu);
                                     % m-2  alternative discretizations
  IS=(sma/(my-1))*ones(my,my*mu);    % the ideal probability of yd 
  yl=-1;                             % lower bound of fy
  yu=1;                              % upper bound of fy
  yr=(yu-yl)/m;                      % increment of fy
  y1=yl+dis*yr;                      % lower bound of the narrow
                                     % band of dis-th convertor
  y2=yl+(dis+1)*yr;                  % upper bound of the narrow
                                     % band of dis-th convertor
  if fy<=y1  
     yd=1;                           % discretized signal
  elseif fy<=y2
    yd=2;
  else 
    yd=3;
  end
%construction of the ideal
 if Ify<=y1 
     IS(1,:)=(1-sma)*uni;            % the ideal of discretized output
  elseif Ify<=y2 
     IS(2,:)=(1-sma)*uni;            % the ideal of discretized output
  else 
     IS(3,:)=(1-sma)*uni;            % the ideal of discretized output
  end