matlab画出曲面 z=4-x*x-y*y及z=3*sqrt(x*x+y*y) 围成的图形

[r,t]=meshgrid(0:.1:1,pi*(0:.1:2));
x=r.*cos(t);
y=r.*sin(t);
z1=4-r.^2;
z2=3*r;
mesh(x,y,z1);
hold on
mesh(x,y,z2)