供参考
[x,y]=meshgrid(-2:0.1:2,-2:0.1:2);
z = exp(-x.^2-y.^2);
figure;
subplot(121);mesh(x,y,z);axis equal
[px,py]=gradient(z,0.1,0.1);
subplot(122);contour(x,y,z);axis equal
hold on;
quiver(x,y,px,py)
