...如下式f=arctan(2z)+(x^2+y^2)/(z^2+1)+arctan(y/x)+z=0答:[x,y,z]=meshgrid(-5:5,-5:5,-5:5);v=atan(2*z)+(x.^2+y.^2)./(z.^2+1)+atan(y./(x+eps))+z;p=patch(isosurface(x,y,z,v,0),'facecolor','r','edgecolor','none','facelighting','gouraud');isonormals(x,y,z,v,p);axis tight equal;view(3);camlight;grid ...