Matlab 大一上测试前的画图练习

1 p38 示例22

x=0:pi/100:2*pi;
y1=2*exp(-0.5*x).*sin(2*pi*x);
y2=2*exp(-0.5*x);
y3=-2*exp(-0.5*x);
plot(x,y1,'m-',x,y2,'m--',x,y3,'m--');
axis([0,2*pi,-2,2]);
grid on;
xlabel('x轴');
ylabel('y轴');
title('函数曲线');
text(3,0.5,'\leftarrow y2=2*exp(-0.5*x)');

 

2，p39 示例23

t=0:pi/20:2*pi;
[x,y,z]=cylinder(2+sin(t),100);
surf(x,y,z);
grid off;
axis off;
shading interp;
colormap(hot);
light('Posi',[2 -1 0]);
light('Posi',[-4,-1,0]);    %设置光源
lighting phong;
material metal;             %设置面的反射属性

 

 3，z=x^2+y^2

x=-2:0.1:2;
y=x;
[xb,yb]=meshgrid(x,y);
zb=xb.^2+yb.^2;
surf(xb,yb,zb);

 

 4，消去z轴上大于4的点

x=-2:0.1:2;
y=x;
[xb,yb]=meshgrid(x,y);
zb=xb.^2+yb.^2;
zb(find(xb.^2+yb.^2>4))=NaN;
surf(xb,yb,zb);

 

 

matlab 可用NaN(区分大小写)对图像进行镂空处理