>	with(plots):

>	gradplot( (x^2+y^2),x=-2..2,y=-2..2);

>	gradplot( (x^2+y^2)^(1/2),x=-2..2,y=-2..2);

>	gradplot( x*y,x=-2..2,y=-2..2);

>	gradplot( x^2-y^2,x=-2..2,y=-2..2);

>	gradplot( x-y ,x=-2..2,y=-2..2);

>