[x,y,z] = meshgrid(linspace(-1.5,1.5,100));
val = 320*(x.^2+9*y.^2/4+z.^2-1).^3-x.^2.*z.^3-9*y.^2.*z.^3/80 ;
isosurface(x,y,z,val,0,abs(y));
axis equal;
