n = size(coor,1);
counter = 0;
for i=1:n
   for j=i+1:n
      dist = norm(coor(i,:)-coor(j,:));
      if (dist<=7)
         counter = counter + 1;
         x(counter) = i;
         y(counter) = j;
      end
   end
end
plot(x,y,'bd')