[matlab] quiver改變箭頭大小

h = quiver(x,y,u,v,scale) % scale可修改長度 (預設為0.9)
set(h,'MaxHeadSize',50) % 設定MaxHeadSize大小改變箭頭旁兩撇的大小 (預設為0.2 )
set(h,'ShowArrowHead','off')
set(h,'ShowArrowHead','on') % 將ShowArrowHead關閉後再開啟才會顯示 (詭異!)