walk_route(DM, A1, startpoint,ch)

function [Rout, id, route] = walk_route(DM, A1, startpoint,ch)

  ns = length(A1);
  m = round(ns/2);
  [nt, points] = sort(DM(startpoint,A1));
  points = A1(points);
  steppair = []; 
  route = [];
  nt = startpoint;
  
  for i=1:2
    ra=(i-1)*m+1; 
    rb=i*m; 
    rc=m;
    if i==2 
        rb=ns; 
        rc=rb-ra+1; 
    end
    na=points(ra:rb);
    nb=[nt na];
    [id,Dm]=walk_propagat(1-DM(nb,nb),1);
    Dm=1-Dm;
    
    if i==1 
        nb=nb(id);
    else
        nb=nb(id(2:rc+1));
    end
    nt = nb(rc);
    steppair = [steppair nb];
    route = [route Dm];
  end
  
route = route(2:ns);
steppair = steppair(2:ns+1);
nb = [fix(0.5*ns) fix(0.33*ns)];
if length(ns) < 4
   nb = [1 2];
end
id = steppair(nb);

Dm = DM(steppair,steppair);
stepRout = diag(Dm,1)';
sortRout = sort(-stepRout);
sortRout = -sortRout;
if ch == 10
na = 1;
else
na = round(0.1*ns);
na = max([na 1]);
end
nt = round(sqrt(ns));
nt = ns-nt;
middleRout = mean(sortRout(na:nt));

m = sortRout(na:ns-1);
rc = m;
ra = rc.*m;
rb = sum(rc);
weightRout = sum(ra)/rb;

weightroute = sort(-route);
weightroute = -weightroute;
m = weightroute(na:ns-1);
rc = m;
ra = rc.*m;
rb = sum(rc);
weightroute = sum(ra)/rb;

if ch == 10
   Rout = [0.5*(weightRout+middleRout) weightroute];
else
   Rout = [0.5*(weightRout+middleRout) mean(m)];
end