clc; clear;
X1 = input('X1= '); Y1 = input('Y1= ');
X2 = input('X2= '); Y2 = input('Y2= ');
 
dx = X2 - X1;
dy = Y2 - Y1;
 
if abs(dx) > abs(dy)       
                       great_axis = dx;
                       less_axis = dy;
                       great = X1;
                       less = Y1;
else
 great_axis = dy;
 less_axis = dx;
 great = Y1;
 less = X1;
end
                             
m = less_axis / great_axis;
er = m - 0.5 * sign(m);
hold on; 
axis ([-100 100 -100 100]);
plot(-100:100,0,'b.');     
plot(0,-100:100,'r.');       
 for i = 0 : abs(great_axis)
  if abs(dx) > abs(dy)
    plot (great, less,'g.');
       x(i+1)=great;  y(i+1)=less;     
  else
    plot (less, great,'g.');
     x(i+1)=less;  y(i+1)=great;        
  end
  e(i+1)=er ;                                   
  if sign(er) == sign(m)
    less = less + sign(less_axis);
    er = er - 1 * sign(m);
  end
great = great + sign(great_axis);
er = er + m;
End
disp(' error    x        y ')
z=[e'  x'  y'];     
disp (z)               
hold off