请教MATLAB画函数图形

%结果自己看.
clear;clc;
[u1 t1]=meshgrid(linspace(0,2,100),linspace(0,20,100));
x1=u1.*sin(t1);
y1=u1.*cos(t1);
z1=t1/4;
figure;mesh(x1,y1,z1)
[x2 y2]=meshgrid(linspace(0,3,100));
z2=sin(x2.*y2);
figure;mesh(x2,y2,z2)
[u3 t3]=meshgrid(linspace(0,2*pi,100),linspace(0,2*pi,100));
x3=sin(t3).*(3+cos(u3));
y3=cos(t3).*(3+cos(u3));
z3=sin(u3);
figure;mesh(x3,y3,z3)