li38.m

这是机械工业张德丰《MATLAB与外部程序接口编程》随书源码

v=-2:0.2:2;
[x,y]=meshgrid(v);
z=x.*exp(-x.^2-y.^2);
[px,py]=gradient(z,.2,.2);
contour(v,v,z);
hold on;
quiver(v,v,px,py);
hold off;