画多个图
x = logspace(-1,1,100); %这个语句表示从10的-1次方到1次方，100个数
y = x.^2;
subplot(2,2,1); %使用subplot语句可以在一个Figure中画多个子图
plot(x,y);
title('Plot');
subplot(2,2,2);
semilogx(x,y);
title('Semilogx');
subplot(2,2,3);
semilogy(x,y);
title('Semilogy');
subplot(2,2,4);
loglog(x,y);
title('Loglog');
%plotyy，在一个图中有两个y轴，可以在一个图上呈现两个图
x = 0:0.01:20;
y1 = 200*exp(-0.05*x).*sin(x);
y2 = 0.8*exp(-0.5*x).*sin(10*x);
[AX,H1,H2] = plotyy(x,y1,x,y2);
set(get(AX(1),'Ylabel'),'String','Left Y-axis');
set(get(AX(2),'Ylabel'),'String','Right Y-axis');
title('Labeling plotyy');
set(H1,'lineStyle','--');
set(H2,'LineStyle',':');
%Histogram,画直方图，看数据的分布形态
y = randn(1,1000);
subplot(2,1,1);
hist(y,10); %10d的意思就是有10个bin
title('Bins = 10');
subplot(2,1,2);
hist(y,50);
title('Bins = 50');
%Bar chat，直方图是一种很powerful的数据呈现形式
x = [1 2 5 4 8];
y = [x;1:5];
subplot(2,3,1);
bar(x);
title('A bargraph of vector x');
subplot(2,3,2);
bar(y);
title('A bargraph of vector y');
subplot(2,3,3);
bar3(y); %bar3可以画3D的图
title('A 3D bargraph');
subplot(2,3,4);
bar(y,'stacked');%stacked将所有的数据叠加起来显示
title('Stacked');
subplot(2,3,5);
barh(y); %将bar横过来画图
title('Horizontal');
%Pie charts，显示不同数据的比例
a = [10 5 20 30];
subplot(2,2,1);
pie(a);
subplot(2,2,2);
pie(a,[0,0,0,1]); %后面中括号里的1代表将这个部分裂开
subplot(2,2,3);
pie3(a,[0,0,0,1]);
subplot(2,2,4);
pie3(a,[1,1,1,1]);
%Boxplot with Error bar
load carsmall
subplot(1,2,1);
boxplot(MPG,Origin);
x = 0:pi/10:pi;
y = sin(x);
e = std(y)*ones(size(x));
subplot(1,2,2);
errorbar(x,y,e); %e代表的是errorbar
%Polar chart
x = 1:100;
theta = x/10;
r = log10(x);
subplot(2,2,1);
polar(theta,r);
theta = linspace(0,2*pi);
r = cos(4*theta);
subplot(2,2,2);
polar(theta,r);
theta = linspace(0,2*pi,6);
r = ones(1,length(theta));
subplot(2,2,3);
polar(theta,r);
theta = linspace(0,2*pi);
r = 1-sin(theta);
subplot(2,2,4);
polar(theta,r);
%要先画一个八边形，先确定每一个角的度数，然后根据度数，可以算出每一个角的坐标x和y
t = (1:2:15)'*pi/8;
x = sin(t);
y = cos(t);
fill(x,y,'r'); %fill来画出x和y围成的8边形的形状，并用红色来进行填充
axis square off; %去掉坐标轴
text(0,0,'STOP','Color','w','FontSize',80,...
'FontWeight','bold','HorizontalAlignment','center'); %设置中间的字符，字号，是否粗体等属性
%Display vakues of a matrix as an "image"
[x, y] = meshgrid(-3:.2:3,-3:.2:3);
z = x.^2 + x.*y + y.^2;
imagesc(z);
axis square;
xlabel('x');
ylabel('y');
colorbar;
colormap(pink); %hot,gray,pink,
接下来是画3D的图，可能会用到如下的指令：
plot3(); 3D line plot
surf(); 3D shaded surface plot
surfc(); Contour plot under a 3D shaded surface plot
surface(); Create surface object
meshc(); Plot a contour graph under mesh graph
contour(); Contour plot of matrix
contourf(); Filled 2D contour plot