1、1第 5 章 数据和函数的可视化5.1 引导5.1.1 离散数据和离散函数的可视化【例 5.1-1】n=(-10:10); y=abs(n); plot(n,y,r.,MarkerSize,20)axis equalgrid on xlabel(n) -10 -8 -6 -4 -2 0 2 4 6 8 10-2024681012n图 5.1-1 离散函数的可视化5.1.2 连续函数的可视化【例 5.1-2】t1=(0:11)/11*pi;t2=(0:400)/400*pi;t3=(0:50)/50*pi;y1=sin(t1).*sin(9*t1);y2=sin(t2).*sin(9*t2);y
2、3=sin(t3).*sin(9*t3);subplot(2,2,1),plot(t1,y1,r.)2axis(0,pi,-1,1),title(1)点过少的离散图形)subplot(2,2,2),plot(t1,y1,t1,y1,r.)axis(0,pi,-1,1),title(2)点过少的连续图形)subplot(2,2,3),plot(t2,y2,r.)axis(0,pi,-1,1),title(3)点密集的离散图形)subplot(2,2,4),plot(t3,y3)axis(0,pi,-1,1),title(4)点足够的连续图形) 0 1 2 3-1-0.500.51 (1)函函函函
3、函函函函0 1 2 3-1-0.500.51 (2)函函函函函函函函0 1 2 3-1-0.500.51 (3)函函函函函函函函0 1 2 3-1-0.500.51 (4)函函函函函函函函图 5.1-2 连续函数的图形表现方法【例 5.1-3】N=9;t=0:2*pi/N:2*pi;x=sin(t);y=cos(t);tt=reshape(t,2,(N+1)/2);tt=flipud(tt);tt=tt(:);xx=sin(tt);yy=cos(tt);subplot(1,2,1),plot(x,y)title(1) 正常排序图形),axis equal off,shgsubplot(1,2,
4、2),plot(xx,yy)title(2) 非正常排序图形),axis equal off,shg 3(1) 函函函函函函 (2) 函函函函函函函图 5.1-3 自变量排列次序对连续曲线图形的影响5.2 二维曲线和图形5.2.1 二维曲线绘制的基本指令 plot【例 5.2-1】clft=(0:pi/50:2*pi);k=0.4:0.1:1;Y=cos(t)*k;subplot(1,2,1)plot(t,Y,LineWidth,1.5)title(By plot(t,Y)xlabel(t)subplot(1,2,2)plot(Y,LineWidth,1.5)title(By plot(Y)x
5、label(row subscript of Y) 40 2 4 6 8-1-0.8-0.6-0.4-0.200.20.40.60.81 By plot(t,Y)t 0 50 100 150-1-0.8-0.6-0.4-0.200.20.40.60.81 By plot(Y)row subscript of Y图 5.2-1 plot(t,Y)与 plot(Y)所绘曲线的区别【例 5.2-2】t=(0:pi/100:pi);y1=sin(t)*1,-1;y2=sin(t).*sin(9*t);t3=pi*(0:9)/9;y3=sin(t3).*sin(9*t3);plot(t,y1,r:,t,
6、y2,-bo)hold onplot(t3,y3,s,MarkerSize,10,MarkerEdgeColor,0,1,0,MarkerFaceColor,1,0.8,0)axis(0,pi,-1,1)hold off%plot(t,y1,r:,t,y2,-bo,t3,y3,s,MarkerSize,10,MarkerEdgeColor,0,1,0,MarkerFaceColor,1,0.8,0) 50 0.5 1 1.5 2 2.5 3-1-0.8-0.6-0.4-0.200.20.40.60.81图 5.2-2 属性控制下所绘曲线5.2.2 坐标控制和图形标识【例 5.2-3】t=0:2
7、*pi/99:2*pi;x=1.15*cos(t);y=3.25*sin(t);subplot(2,3,1),plot(x,y),axis normal,grid on,title(Normal and Grid on)subplot(2,3,2),plot(x,y),axis equal,grid on,title(Equal)subplot(2,3,3),plot(x,y),axis square,grid on,title(Square)subplot(2,3,4),plot(x,y),axis image,box off,title(Image and Box off)subplot(
8、2,3,5),plot(x,y),axis image fill,box offtitle(Image and Fill)subplot(2,3,6),plot(x,y),axis tight,box off,title(Tight) 6-2 0 2-4-2024 Normal and Grid on-2 0 2-202Equal-2 0 2-4-2024 Square-1 0 1-202Image and Box off-1 0 1-1-0.500.51Image and Fill-1 0 1-202Tight图 5.2-3 各种轴控制指令的不同影响【例 5.2-4】clf;t=0:pi/5
9、0:2*pi;y=sin(t);plot(t,y)axis(0,2*pi,-1.2,1.2)text(pi/2,1,fontsize16leftarrowitsin(t)fontname隶书极大值)title(y=sin(t)xlabel(t)ylabel(y) 70 1 2 3 4 5 6-1-0.8-0.6-0.4-0.200.20.40.60.81 sin(t)极 大 值y=sin(t)ty图 5.2-4 试验标识的图形【例 5.2-5】clf;t=6*pi*(0:100)/100;y=1-exp(-0.3*t).*cos(0.7*t);plot(t,y,r-,LineWidth,3)h
10、old ontt=t(find(abs(y-1)0.05);ts=max(tt);plot(ts,0.95,bo,MarkerSize,10)hold offaxis(-inf,6*pi,0.6,inf)set(gca,Xtick,2*pi,4*pi,6*pi,Ytick,0.95,1,1.05,max(y)set(gca,XtickLabel,2*pi;4*pi;6*pi)set(gca,YtickLabel,0.95;1;1.05;max(y)grid ontext(13.5,1.2,fontsize12alpha=0.3)text(13.5,1.1,fontsize12omega=0.7
11、)cell_string1=fontsize12uparrow;cell_string2=fontsize16 fontname隶书镇定时间;cell_string3=fontsize6 ;cell_string4=fontsize14rmt_s = num2str(ts);text(ts,0.85,cell_string,Color,b,HorizontalAlignment,Center)title(fontsize14it y = 1 - e -alpha tcosomegat)xlabel(fontsize14 bft rightarrow)ylabel(fontsize14 bfy
12、rightarrow) 82*pi 4*pi 6*pi0.9511.05max(y)=0.3=0.7 镇 定 时 间ts = 9.6133y = 1 - e - tcostt y 图 5.2-5 二阶阶跃响应图的标识5.2.3 多次叠绘、双纵坐标和多子图【例 5.2-6】t=2*pi*(0:20)/20;y=cos(t).*exp(-0.4*t);stem(t,y,g,Color,k);hold onstairs(t,y,:r,LineWidth,3)hold offlegend(fontsize14it stem,fontsize14it stairs)box on 90 1 2 3 4 5
13、 6 7-0.4-0.200.20.40.60.81stemstairs图 5.2-6 离散信号的重构【例 5.2-7】clf;dx=0.1;x=0:dx:4;y=x.*sin(x);s=cumtrapz(y)*dx;a=plotyy(x,y,x,s,stem,plot);text(0.5,1.5,fontsize14ity=xsinx)sint=fontsize16int_fontsize80 x;ss=fontsize14its=,sint,fontsize14itxsinxdx;text(2.5,3.5,ss)set(get(a(1),Ylabel),String,被积函数 ity=xs
14、inx)set(get(a(2),Ylabel),String,ss)xlabel(x) 100 0.5 1 1.5 2 2.5 3 3.5 4-505y=xsinxs=0 xxsinxdx函函函函y=xsinxx024s=0 xxsinxdx图 5.2-7 函数和积分【例 5.2-8】clf;t=(pi*(0:1000)/1000);y1=sin(t);y2=sin(10*t);y12=sin(t).*sin(10*t);subplot(2,2,1),plot(t,y1);axis(0,pi,-1,1)subplot(2,2,2),plot(t,y2);axis(0,pi,-1,1)subplot(position,0.2,0.1,0.6,0.40)plot(t,y12,b-,t,y1,-y1,r:)axis(0,pi,-1,1) 0 1 2 3-1-0.500.510 1 2 3-1-0.500.510 0.5 1 1.5 2 2.5 3-1-0.500.51图 5.2-8 多子图的布置
