Matlab基础与应用教程答案(人民邮电)

第1章一、思考题4.（1）B=A(2:5,1:2:5)（2）A(7)=[]（3）A=A+30（4）size(A)（5）t(find(t==0))=eps（6）t=reshape(x,3,4)（7）abs('matlab')（8）char(93)5.A=[97,67,34,10;-78,75,65,5;32,5,-23,-59;0,-12,54,7](1)B=A(1:3,:)C=A(:,1:2)D=A(2:4,3:4)E=B*C(2)A(find(A=50&A=100))二、实验题1.x=-74/180*pi;y=-27/180*pi;sin(x*x+y*y)/sqrt(tan(abs(x+y)))+pi2.a=-3.0:0.1:3.0;exp(-0.3*a).*sin(a+0.3)3.x=[2,4;-0.45,5];log(x+sqrt(1+x.*x))/24.A=[3,54,2;34,-45,7;87,90,15];B=[1,-2,67;2,8,74;9,3,0];（1）A*Bans=12943241977-407-105240259112489A.*Bans=3-10813468-3605187832700（2）A^3ans=-28917240246-4368137883-2591012766917133325250438673A.^3ans=27157464839304-911253436585037290003375（3）A/Bans=-5.88455.3549-0.20286.3554-5.65964.3293-6.63256.20789.0241B/Aans=30.285519.2643-8.561433.439421.1547-9.3974-0.7443-0.39380.2830（4）[A,B]ans=35421-26734-4572874879015930[A([1,3],:);B^2]ans=3542879015600183-816842827261568255.a=1+2i;b=3+4i;c=exp(pi*i/6)c=0.8660+0.5000ic+a*b/(a+b)ans=1.6353+1.8462i第2章一、思考题3.s=0;forn=0:63s=s+2^n;enddisp(s)n=0:63;s=sum(2.^n)二、实验题1.x=input('输入一个四位整数：');y=[fix(x/1000),mod(fix(x/100),10),mod(fix(x/10),10),mod(x,10)]z=mod((y+7),10)x=z(3)*1000+z(4)*100+z(1)*10+z(2)2.gh=input('输入工号');h=input('输入工时');dj=84;ifh120gz=dj*120+1.15*dj*(h-120);elseifh60gz=dj*h-700;elsegz=dj*h;endformatbank;display([gh,gz])3.循环结构n=input('inputn:');s=0;fork=1:ns=s+1/k^2;enddisplay(sqrt(s*6))向量运算n=input('inputn:');k=1:n;display(sqrt(sum(1./k.^2)*6))4.y=0;k=0;whiley3k=k+1;y=y+1/(2*k-1);enddisplay([k-1,y-1/(2*k-1)])5.x0=0;x=1;k=0;a=input('a=');b=input('b=');whileabs(x-x0)=1e-5&&k500x0=x;x=a/(b+x0);k=k+1;enddisplay([k,x]);display([(-b+sqrt(b^2+4*a))/2,(-b-sqrt(b^2+4*a))/2]);6.y=fun(40)/(fun(30)+fun(20))（1）函数文件fun.mfunctionf=fun(n)f=n+log(n^2+5);（2）函数文件fun.mfunctionf=fun(n)a=1:n;f=sum(a.*(a+1));第3章一、思考题4.t=0:0.01:1.5;y=sqrt(3)/2*exp(-4*t).*sin(4*sqrt(3)*t+pi/3);5.x=-10:0.01:10;y=linspace(-6,6,size(x,2))z=x.^3+3*x.*y.^2;plot3(x,y,z)6.x=100:100:400;y=100:100:400;z=[636,697,624,478;698,712,630,478;680,674,598,412;662,626,552,334];[X,Y]=meshgrid(x,y);mesh(X,Y,z)二、实验题1.（1）x=-10:0.01:10;plot(x,x-x.^3/3/2)（2）plot(x,exp(-x.*x/2)/2/pi)（3）x=-8:0.01:8;plot(x,sqrt((64-x.*x)/2))（4）t=0:pi/100:6*pi;plot(t.*sin(t),t.*cos(t))2.（1）x1=linspace(0,1,100);y1=2*x1-0.5;t=linspace(0,pi,100);x=sin(3*t).*cos(t);y=sin(3*t).*sin(t);plot(x1,y1,'r-',x,y,'b:');text(0.4,1,'y=2x-0.5');text(-0.4,0.5,'x=sin(3t)cos(t)');text(-0.4,0.3,'y=sin(3t)sin(t)');（2）subplot(1,2,1);scatter(x1,y1,10)title('y=2x-0.5');subplot(1,2,2);scatter(x,y,10)3.subplot(1,21);x=1:1:100;y=sin(1./x);plot(x,y)subplot(1,2,2);fplot('sin(1/x)',[1,100])4.subplot(2,2,1);bar(t,y);subplot(2,2,2);stairs(t,y);subplot(2,2,3);stem(t,y)subplot(2,2,4);semilogy(t,y);5.theta=linspace(-pi,pi,100);ro=5.*cos(theta)+4;polar(theta,ro);fi=linspace(0,2*pi,100);a=1r=a.*(1+cos(fi));polar(fi,r);6.t=0:pi/20:2*pi;x=exp(-t./20).*cos(t);y=exp(-t./20).*sin(t);z=t;plot3(x,y,z);t=0:0.01:1;x=t;y=t.^2;z=t.^3;plot3(x,y,z);7.x=-30:0.1:0;y=0:0.1:30;[x,y]=meshgrid(x,y);z=10.*sin(sqrt(x.^2+y.^2))./sqrt(1+x.^2+y.^2);meshc(x,y,z);8.x=linspace(-3,3,100);y=linspace(-3,3,100);[xy]=meshgrid(x,y);fxy=-5./(1+x.^2+y.^2);i=find(abs(x)=0.8&abs(y)=0.5);fxy(i)=NaN;surf(x,y,fxy)9.u=linspace(1,10,100);v=linspace(-pi,pi,100);[u,v]=meshgrid(u,v);x=3.*u.*sin(v);y=2.*u.*cos(v);z=4*u.^2;x=3*u.*sin(v);y=2*u.*cos(v);z=4*u.^2;surf(x,y,z);shadinginterp;light('position',[1,0,1]);10.t=0:pi/100:2*pi;y=sin(t);comet(t,y)第4章一、思考题5.（1）A=eye(3);（2）C=100+(200-100)*rand(5,6);（3）D=1+sqrt(0.2)*randn(1,500);（4）E=ones(size(A));（5）A=A+30*eye(size(A));（6）B=diag(diag(A))二、实验题1.P=pascal(5);H=hilb(5);Dp=det(P);Dh=det(H);Kp=cond(P);Kh=cond(H);P矩阵的性能更好，因为Kp较小2.A=[1,-1,2,3;0,9,3,3;7,-5,0,2;23,6,8,3]B=[3,pi/2,45;32,-76,sqrt(37);5,72,4.5e-4;exp(2),0,97]A1=diag(A);B1=diag(B);A2=triu(A);B2=triu(B);A3=tril(A);B3=tril(B);rA=rank(A);rB=rank(B);nA=norm(A);nb=norm(B);cA=cond(A);cB=cond(B);3.A=[31,1,0;-4,-1,0;4,-8,-2]；[V,D]=eig(A);4.A=diag([-1,-1,-1,-1],-1)+diag([-1,-1,-1,-1],1)+diag([2,2,2,2,2])b=[1,0,0,0,0]';x1=inv(A)*b;x2=A\b;[L,U]=lu(A);x3=U\(L\b);[Q,R]=qr(a);[Q,R]=qr(A);x4=R\(Q\b)R=chol(A);x5=R\(R'\b)5.B=sparse(A);x1=inv(B)*b;x2=B\b;[L,U]=lu(B);x3=U\(L\b);第5章一、思考题3.A=randn(10,5);mean(A)std(A)max(max(A))min(min(A))sum(A,2)sum(sum(A))sort(A,1)sort(A,2,'descend')二、实验题1.A=rand(1,30000);mean(A)std(A)max(A)min(A)size(find(A0.5))/size(A)2.h=[466,715,950,1422,1635];w=[7.04,4.28,3.40,2.52,2.13];hh=[500,900,1500];ww=interp1(h,w,hh,'spline')3.x=linspace(1,10,50);y=log(x);f=polyfit(x,y,5);yy=polyval(f,x);plot(x,y,'r-',x,yy,'g.')4.N=64;%采样点数T=5;%采样时间终点t=linspace(0,T,N);%给出N个采样时间ti(I=1:N)x=3*exp(-t);%求各采样点样本值xdt=t(2)-t(1);%采样周期f=1/dt;%采样频率(Hz)X=fft(x);%计算x的快速傅立叶变换XF=X(1:N/2+1);%F(k)=X(k)(k=1:N/2+1)f=f*(0:N/2)/N;%使频率轴f从零开始plot(f,abs(F),'-*')%绘制振幅-频率图xlabel('Frequency');ylabel('|F(k)|')5.（1）p1=[12007];p2=[1-2];p3=[10051];p12=conv(p1,p2);p=p12+[zeros(1,size(p12,2)-size(p3,2)),p3];roots(p)（2）A=[-1,4,3;2,1,5;0,5,6];Px=polyval(p,A)Pxm=polyvalm(p,A)6.（1）z=fzero('3*x-sin(x)+1',0)（2）建立函数文件myfun.mfunctionF=myfun(X)x=X(1);y=X(2);F(1)=x*x+y*y-9;F(2)=x+y-1;在命令窗口中输入以下