>	with(plots);

>	plot3d((x^2+y^2-4)^2-x^2*y^2,x=-3..3,y=-3..3);

>	contourplot((x^2+y^2-4)^2-x^2*y^2,x=-3..3,y=-3..3,contours=100,grid=[100,100]);

>

with(plots); addcoords(z_cylindrical,[z,r,theta],[r*cos(theta),r*sin(theta),z]); plot3d( (r^2-4)^2-0.25*r^4*(sin(2*theta))^2, r=0..3, theta=0..2*Pi,coords=z_cylindrical,grid=[100,100]); contourplot( (r^2-4)^2-0.25*r^4*(sin(2*theta))^2, r=0..3, theta=0..2*Pi,coords=z_cylindrical,contours=30,grid=[100,100]);

>	plot3d(sin(x)* sin(y),x=-2*Pi..2*Pi, y=-2*Pi..2*Pi,grid=[100,100]);

>	contourplot(sin(x)* sin(y),x=-2*Pi..2*Pi, y=-2*Pi..2*Pi,grid=[100,100]);

>	plot3d((x^2+3*y^2)*exp(-x^2-y^2),x=-2..2,y=-2..2,grid=[100,100]);

>	contourplot((x^2+3*y^2)*exp(-x^2-y^2),x=-2..2,y=-2..2,grid=[100,100]);

>

>