function parallelogrammesv2(A,u,v,x,n)
% exemple: parallelogrammesv2([-1;2],[-2;3],[1;3],0.1,25)
  clf;hold on;axis equal
  calcul=@(A,u,v,x) deal(A+x*u,u+x*(v-u),v-x*(u+v));
  getX=@(A,u,v) [A,A+u,A+u+v,A+v,A];
  plot_para=@(X,color) plot(X(1,:),X(2,:),color);
  X=getX(A,u,v);
  plot_para(X,'k')
  for i=1:n
    [A,u,v]=calcul(A,u,v,x);
    X=getX(A,u,v);
    plot_para(X,'b')
  end
end
