《MATLAB教程及实训 第4版》-曹弋 习题解答

PAGEPAGE335习题答案第1章MATLAB概述1．（1）B（2）D（3）B（4）B（5）C2，3，4略5．formatratformatlongformatshorte6，7，8，9，10，11，12，13，14略第2章MATLAB基本运算1．（1）A（2）C（3）A（4）B（5）C（6）C（7）C（8）B（9）B（10）C（11）D（12）C（13）B（14）B（15）C（16）D（17）B（18）C（19）B（20）C2.略3.x1=0:0.4*pi:4*pix2=linspace(0,4*pi,10)4.a=[123;456;789]a(1,3);a(6)a(2:end,:)l1=logical([101])l2=logical([101])a(l1,l2)5.a=magic(3)b=eye(3)c=[a;b]d=[ab]e=d(3,:)6，7略8.A=[2-312;1301;1-118;71-22];B=[8;6;7;5];X=A\B9，10略11．a='hello';a=a+4;a=char(a)a=rot90(a,2)12.t=0:0.2:20;f=10*exp(-2*t).*sin(4*t)f1=(f>=0).*f13．a(:,:,1)=[12;34];a(:,:,2)=[12;21];a(:,:,3)=[12;22];a1=reshape(a,[3,2,2])14．x=0:20;y=sin(x);x1=x.*((x>pi)&(x<4*pi))y1=sin(x1).*(sin(x1)>0)15．Y=2021;M=10;D=[1;2;3;4;5;6;7];t=datetime(Y,M,D)temp=[30;31;28;29;30;33;35];TT=timetable(t,temp)16.a=[123;456;789]size(a)ischar(a)17．T=readtable('exe1_17.xlsx','Range','A1:C1'))18.v={{'Tom','NewYork},{'Mary','Paris'},{'John','London'};v={{'Tom','NewYork'},{'Mary','Paris'},{'John','London'}};studentsMap=containers.Map(k,v);v=values(studentsMap)v{2}(2)19．ax=[54321];bx=[301];cx=conv(ax,bx)polyval(cx,2)p=roots(cx)f=polyval(cx,2)[B,A]=residue(ax,bx)20．x=0:20;f=[54321];y1=polyval(f,x)f1=polyfit(x,y1,2)f2=polyfit(x,y1,3)f3=polyfit(x,y1,4)第3章数据的可视化1．（1）A（2）B（3）A（4）B（5）C（6）B（7）B（8）D（9）C（10）D2．y=0:0.1:10;plot(x,1,1,y,x,y)plot(x,1,1,y,x,y)3.plot(2*sin(x),2*cos(x))axisequal4.t=0:0.1:2;y=5*t.*sin(2*pi*t);plot(t,y)5.t1=0:0.1:2*pi;t2=pi:0.1:4*pi;y1=sin(t1);y2=sin(2*t2);plot(t1,y1,'b._')gtext({'y=sin(t)';'y=sin(2t)'})6.x=-2:0.1:6;y1=x;y2=x.^2;y3=exp(-x);plot(x,y1,x,y2,x,y3)title('三条曲线')xlabel('x')legend('y1=x','y2=x^2','y3=exp(-x)')text(1,1,'x=1')line(1,-2:0.1:10)7.x=[65,98,68,75,88,78,82,94,85,56];y=[5565758595];hist(x,y)

;N=hist(x,y)pie(N,{'<60','60-70','70-80','80-90','90-100'})8.x=[6578869369;7585929570;7280799272];x=x';bar(x)stairs([1:3],x(1,:),'r')axis([0,5,0,100])holdonstairs([1:3],x(2,:),'b');stairs([1:3],x(3,:),'g')stairs([1:3],x(4,:),'k');stairs([1:3],x(5,:),'y')9.w=logspace(-2,3,20);Lw=-20*log10(w.*sqrt((0.5*w).^2+1));semilogx(w,Lw)loglog(w,Lw)10.略11.x=0:10;y=cos(10*x);cylinder(y)view([180,0])12.x=-5:0.2:5;y=-5:0.2:5;[X,Y]=meshgrid(x);z=sqrt(X.^2+Y.^2)+eps;mesh(z)colormap(gray)colorbar;view(2)第4章符号运算1．（1）D（2）B（3）B（4）A（5）C（6）C（7）D（8）B（9）C（10）D2.f=sym(sin(x))+sym(cos(y))symsxy

;f=sin(x)+cos(y)3.x=sym(pi,'d')x=sym(pi,'f')x=sym(pi,'r')4，5略6.a=log(10);a1=sym(a)a2=vpa(a,18)7.wyxresult8.symsx;f=cos(x)+sqrt(-sin(x)^2)collect(f);expand(f);simplify(f)9.symsx;f=x^2-1g=factor(f)g1=subs(g,y,x-1);g1=subs(g,5,x-1)f1=finverse(f)10．symsx;f=x^3+5*x^2+4*x+1g=exp(-x)compose(f,g)p=sym2poly(f)11.symsax;f=sin(a*x)diff(f);diff(f,'a');diff(f,'x',2);diff(f,'a',2)int(f,'x',0,2*pi)12.symst

;y=2*t*sin(t+pi/4)limit(y,t,1)symsum(y,t,1,10)13.symsst;f1=3/((s+1)*(s+2));f2=1/(s+2)^2f=f1+f2[num,den]=numden(f)ilf=ilaplace(f,s,t)14.比较第二章的习题8，看看两种解方程的方法。 symsx1x2x3x4[x1,x2,x3,x4]=solve(2*x1-3*x2+x3+2*x4==8,x1+3*x2+x4==6,x1-x2+x3+8*x4==7,7*x1+x2-2*x3+2*x4==5)15.clear

;symsy(x)dsolve(diff(y,x)+y*tan(x)==cos(x))dsolve(diff(y,x)+y*tan(x)==cos(x),y(0)==2)16.clear;symsy(x)y=tan(x)

;fplot(y)第5章程序设计和M文件1．（1）B（2）C（3）A（4）C（5）B（6）C（7）D（8）D（9）B（10）A2.略3.clear;a=55;ifa>=60b='合格'elseb='不合格'end4.x=0:0.1:10;y=x;if(x+y)>1z=0.5*exp(-0.5*y.^2-3*y.^2-y)elseif(x+y)<=-1z=0.7*exp(-y.^2-6*y.^2)elsez=0.5*exp(-0.5*y.^2-3*x.^2+x)endplot3(x,y,z)5.functionz=f(w,t)y=sin(w.*t);z=[t;y]6.cleara=input('inputa=')b=rem(a,2);switchbcase0disp([num2str(a),'是偶数'])case1disp([num2str(a),'是奇数'])endclearsum=0forn=1:1000sum=n^n+sumclearsum=0forn=1:1000sum=n^n+sumifsum>1000breakendendclearsum=0;n=1;whilesum<1000sum=n^n+sumn=n+1end8.function[y1,y2]=f(x1,x2)ifnargin==0ifnargout==0y1=0;endelseifnargin==1ifnargout==1y1=x1;endelseifnargout==2y1=x1;y2=x2;endend9.functionvarargout=f(varargin)lin=length(varargin);iflin==0varargout{1}=0;elsesum=0;forn=1:linsum=sum+varargin{n};varargout{1}=sum;endendfunctionz=f1(x,y)z=0.5*exp(-0.5*y.^2-3*y.^2-y)functionz=f2(x,y)functionz=f1(x,y)z=0.5*exp(-0.5*y.^2-3*y.^2-y)functionz=f2(x,y)z=0.7*exp(-y.^2-6*y.^2)functionz=f3(x,y)z=0.5*exp(-0.5*y.^2-3*x.^2+x)functionf()x=0:0.1:10;y=x;if(x+y)>1z=f1(x,y)elseif(x+y)<=-1z=f2(x,y)elsez=f3(x,y)endplot3(x,y,z)pcodef11.fhnd=@(x)(log10(x)+sin(2*x));y=fhnd(2)saveexe10fhnd12．fhnd=@humps;s1=functions(fhnd)s=func2str(fhnd)13.y=@(x)x.^3+2*x.^2+3*x+6fplot(y,[0,10])14.fhnd=@(x)(-exp(-x)*abs(sin(sin(x))))y=fminbnd(fhnd,0,10)15.fhnd=@(x)(sin(x))y=quad(fhnd,0.1,1)16.fhnd=@(t,y)(y*tan(y)-cos(y));[t,y]=ode45(fhnd,[0,20],1);plot(t,y)第6章MATLAB高级图形设计1．（1）D（2）C（3）C（4）D（5）B（6）C（7）B（8）D（9）C（10）C2.x=0:0.1:10;y=exp(-x).*sin(x);h_l=plot(x,y,':')set(gca,'ygrid','on');set(h_l,'linewidth',2)set(gcf,'color','y')h_t=title(gca,'y=exp(-x)*sin(x)');set(h_t,'fontsize',20)3.略4.略5.略6.prompt={'输入正弦的幅值','输入正弦的相角'};defans={'1','0'};n=inputdlg(prompt,'输入',1,defans)message=['正弦的幅值和相角是',n{1},'和',n{2}];msgbox(message,'显示')7.[f,p]=uigetfile('*.m','打开文件')8.x1=imread('002','jpg');imfinfo('002.jpg')imwrite(x1,'002.bmp');imfinfo('002.bmp')9.x1=imread('002','jpg');x2=x1*2;imshow(x2)10.y=audioread('ding.wav');size(y)y=[y;y;y];sound(y)size(y)11.x=0:0.1:10;k=1forn=xy=sin(0:0.1:n);x1=0:0.1:n;plot(x1,y);axis([0,10,-1.5,1.5])M(k)=getframek=k+1end12.x=0:0.1:10;p=plot(x,sin(x),'r')h=line(0,0,'color','blue','marker','.','markersize',20,'erasemode','xor');fork=0:0.1:20*piset(h,'xdata',k,'ydata',sin(k))pause(0.005)drawnowend第7章Simulink仿真环境1．（1）D（2）B（3）C（4）B（5）A2.略3.参数设置略。4.参数设置略。5.参数修改略。6.[t,x]=sim('exe7_2',[020]); plot(t,x)7.8.封装设置略，子系统如下：9.第8章线性控制系统的分析1．（1）B（2）C（3）B（4）D（5）D2.num=[123];den=[125101];[z,p,k]=tf2zp(num,den)[a,b,c,d]=tf2ss(num,den)[r,p,k]=residue(num,den)3.num=[48];den=[1651];G=tf(num,den)c=class(G)is=issiso(G)Gd=c2d(G,0.1,'tustin')4.G1=tf(1,[125]);G2=tf(1,[11]);G3=tf(3,[15]);G4=tf(1,[111]);G34=parallel(G3,G4)%计算并联环节G134=series(G1,G34)%计算串联环节G=feedback(G2,G134)%计算反馈环节5.使用linmod函数获得simulink模型的状态空间模型。6.num=5;den=[125];G=tf(num,den)[wn,zeta,p]=damp(G)forzeta=[0.10.30.5][num1,den1]=ord2(wn(1),zeta);G1=tf(num1,den1);step(G1)ho