clear,[x,y,z]=meshgrid(-10:.01:10,-10:.01:-10,-10:.01:10); [curlx,curly,curlz]=curl(x,y,z,u,v,w); if x*x+y*y=4 curl(x,y,z,u,v,w)=[y,x,0] elseif (x.-1)*(x.-1)+z*z=4 curl(x,y,z,u,v,w)=[z,0,x-1] else curl(x,y,z,u,v,w)=[0,0,0] div(x,y,z,u,v,w)=0; end end hold on; quiver3(x,y,z,u,v,w)