(commands used to produce figure above)

>	p1:=plot3d(x^2+y,x=-1..1,y=-1..1): p2:=fieldplot3d(<-y,x,1/2/Pi>,x=-1..1,y=-1..1,z=-0.8..1.8,color=red,arrows=THICK,grid=[7,7,7]):display(p1,p2);

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