figure(1)
ezplot('(x^2+y^2)^2-4*(x^2-y^2)',[-2,2,-2,2]);
hold on
ezplot('x^2+y^2-x*y-3',[-2,2,-2,2]);
axis equal
hold off
 
figure(2)
ezplot3('t*sin(3*t)','t*cos(3*t)','t',[0,3*pi]);
axis tight 







