And again let us see that what will happen to divergent of q, we have divergent q is 0 that is we have del u by del x plus del v by del y plus del w by del z this is equal to 0. And if we put e is equal to phi x, v is equal to phi y and w is equal to phi z, then we will get del square phi by del x square plus del square phi by del y square plus del square phi by del z square is 0.