function dist = checkingLine(GapValue, L1, L2, n, j, points)
  q1 = points(1,j);
  q2 = points(2,j);
  q1_ = points(1,n);
  q2_ = points(2,n);
  
  
  dist = 0;
  if n==j
    dist = NaN;
  endif
  if q1 != q1_
          
      %defining Q2 as a function of Q1
      A = (q2_- q2)/(q1_ - q1);
      B = q2 - A * q1;
      Q2 = @(Q1) A*Q1+B;
      
      %getting the sampling direction
      if q1 > q1_
        gap = -GapValue;
      else
        gap = GapValue;
      endif
      
      
      %getting the sample points
      for g=q1:gap:q1_
        Q1test = g;
        Q2test = Q2(g);
        
        %Is the end effector colliding with obstacle
        [Xtest, Ytest]=MyFK(L1,L2,Q1test,Q2test);
        
        %filling the obstacle matrix
        if dist !=NaN && (Ytest >= L1 || Ytest <= -L1 || (Xtest>=-L2 && Xtest<=L2 && Ytest>=-L2 && Ytest<=L2)) %verifie les obstacles
          dist = NaN;
          
          %{
          X_space = [X_space Xtest];
          Y_space = [Y_space Ytest];
          %}
        endif
        
      endfor
      if dist ==0 && n!=j
          dist = sqrt( (points(1,j)-points(1,n))^2 + (points(2,j)-points(2,n))^2);
      endif
    endif
      
endfunction