《MATLAB及其在大學物理課程中的應用》習題答案___電子科大__第二版.doc

1、 第二章1、x=2,4;y=x.3+(x-0.98).2./(x+1.35).3-5*(x+1./x)2、y=cos(pi/3)-(9-sqrt(2)(1/3)3、a=3;A=4;b=a.2;B=b.2-1;c=a+A-2*B;C=a+2*B+c4、 x=1 2 3;4 5 6;7 8 9 Desktop-Workspace,雙擊變量x5、clearx=magic(3)y=randn(3,3)xy=x,yyx=x,yz=xy(:,1:2)6、clearx=eye(4,4)y=triu(x)7、clearx=rand(4,5)y=x(1,2,:)z=(y=0.3).*y8、clearx=rand

2、n(5,5)y=inv(x)9、clearx=randn(5,5)z=x510、clearA=1,4,8;-3,6,-5;2,-7,-12;B=5,4,3;6,-2,3;-1,3,-9;C=A*BD=A.*B11、clearx=linspace(0,2*pi,125);y=cos(x).*(0.5+3*sin(x)./(1+x.2);plot(x,y)12、z=-45:1:45;x=z.*sin(3*z);y=z.*cos(3*z);plot3(x,y,z);13、x=-2:0.1:2,y=x;x,y=meshgrid(x,y);z=x.2.*exp(-x.2-y.2)surf(x,y,z);

3、14、x=-2:0.1:2,y=x;x,y=meshgrid(x,y);z=x.2.*exp(-x.2-y.2);surf(x,y,z);z1=0.05*x-0.05*y+0.1;hold on,mesh(x,y,z1);15、（1）n=2;alfa=0;t=0:0.1:10;x=cos(t);y=sin(n*t+alfa);subplot(2,2,1);plot(t,x,t,y);（2）n=2;alfa=0;t=0:0.1:10;x=cos(t);y=sin(n*t+alfa);subplot(2,2,1);plot(t,x,t,y);n=2;alfa=pi/3;t=0:0.1:10;x=c

4、os(t);y=sin(n*t+alfa);subplot(2,2,2);plot(t,x,t,y);n=2;alfa=pi/2;t=0:0.1:10;x=cos(t);y=sin(n*t+alfa);subplot(2,2,3);plot(t,x,t,y);n=2;alfa=pi;t=0:0.1:10;x=cos(t);y=sin(n*t+alfa);subplot(2,2,4);plot(t,x,t,y);球體clearfor i=1:100 for j=1:100 x(i,j)=i/100*cos(j*2*pi/100); y(i,j)=i/100*sin(j*2*pi/100); z(

5、i,j)=sqrt(1.001-x(i,j)2-y(i,j)2); endendsurf(x,y,z);hold on;surf(x,y,-z);axis equal棱錐clearfor i=1:100 for j=1:100 x(i,j)=i/100*cos(j*2*pi/4); y(i,j)=i/100*sin(j*2*pi/4); z(i,j)=sqrt(x(i,j)2+y(i,j)2); endendsurf(x,y,-z);求最大值x=67 87 56 99 43max=0;for i=1:5 if max=x(i) max=max; else max=x(i) endendmax求

6、最小值x=67 87 56 99 43min=inf;for i=1:5 if min=x(i) min=min; else min=x(i) endendmin求和x=67 87 56 99 43;sum=0;for i=1:5 sum=sum+x(i)endsum第三章1、h0=446,714,950,1422,1634;t0=7.04,4.28,3.40,2.54,2.13;t1=interp1(h0,t0,500,linear)2、x0=1,0,-1;y0=0,1,0;p=polyfit(x0,y0,3);x=-1:0.1:1;y=polyval(p,x);plot(x,y,-x,-y

7、),axis equal3、clearx0=1.0,1.1,1.2,1.3,1.4;y0=0.25,0.2268,0.2066,0.1890,0.1736;p=polyfit(x0,y0,3);p1=polyder(p);y=polyval(p1,1.0,1.2)4、p=3 4 7 2 9 12;r=roots(p)5、r=-3 -5 -8 -9;p=poly(r)6、function ypie=fun1(x,y)ypie=x.2./y-x.*cos(y);x,y=ode45(fun1,0,5,1)plot(x,y)7、function y=fun2(x)y=x.4-3*x3+5*cos(x)

8、+8;fplot(fun2,1,5)hold on;x=0:5;y=0*x;plot(x,y)a=fzero(fun2,2)b=fzero(fun2,3)8、a=2 4 9;4 2 4;9 4 18;v,gama=eig(a)9、function xpie=fun3(t,x)f=exp(-t)xpie=0 1 0 0;1 0 0 -1;0 0 0 1;0 -1 -1 0*x+0;1;0;0*ft,x=ode45(fun3,0,5,0 0 0 0);plot(t,x(:,1),b,t,x(:,3),r)10、function f=fun4(x,y)f=4*(x-y)-x.2-y.2;v=-2:0

9、.2:2;x,y=meshgrid(v)z=fun4(x,y);surf(x,y,z)求極小值 （有誤）function f=fun5(x,y)x=v(1);y=v(2)f=-(4*(x-y)-x.2-y.2);v=-50:2:50;x,y=meshgrid(v)z=fun4(x,y);surf(x,y,z)min=fminsearch(fun4,0,0)11、function f=fun6(x,y)f=sin(y)+exp(x)-x.*y.2ezplot(fun6)12、function f=fun7(x,y)f=(x-y).2.*(sin(x+y).2 s=dblquad(fun7,pi,

10、2*pi,0,pi)14、a=randn(4,4)l,u=lu(a)a=randn(4,4)u,gama,v=svd(a)15、b=3 0.5 4;a=3 4 5 6;r,p,k=residue(b,a)b=3 0.5 4;a=3 4 5 6;r,p,k=residue(b,a)t=0:0.1:100;y=0*t;for i=1:3 y=y+r(i)*exp(p(i)*t)endplot(t,y)b=3 0.5 4;a=3 4 5 6;impulse(b,a)b=3 0.5 4;a=3 4 5 6;step(b,a)第四章1、n=1:11;x=cos(pi/6*n);subplot(2,1,1

11、);stem(x);y=abs(fft(x);subplot(2,1,2);stem(y);clearn=0:11;x=cos(pi/6*n);subplot(2,1,1);stem(x);y=abs(fft(x);subplot(2,1,2);stem(y);2、（有誤）n=0:19;x=5*0.6.n;subplot(3,1,1);stem(n,x);for i=-20:39 xl(i+21)=x(mod(i+40,20)+1);endn1=-20:39;subplot(3,1,2);stem(n1,x1);x2=x1(10:29);subplot(3,1,3);stem(n,x2)新方法

12、m=10;e=0:19;c=0.6;k=5;a=k*c.e;a=a;b=circshift(a,m);L=length(a)-1;n=0:L;subplot(2,1,1);stem(n,a);axis(0,L,min(a),max(a);subplot(2,1,2);stem(n,b);axis(0,l,min(a),max(a)3、x=0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0 0 0 0 0 0 0 0;h=1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0y=conv(x,h);stem(y)4、x=0.

13、8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0 0 0 0 0 0 0 0;h=1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0y=conv(x,h);subplot(2,1,1);stem(y) xx=fft(x);hh=fft(h);yy=ifft(xx.*hh);subplot(2,1,2);stem(yy)5、b=2 3;a=1 0.4 1;z p k=tf2zp(b,a)6、b=4 15.6 6 2.4 -6.4;a=3 2.4 6.3 -11.4 6;z p k=tf2zp(b,a)7、b=18;a=18

14、 3 -4 -1;r p k=residue(b,a)8、b=0.2 0.3 1;a=1 0.4 1;freqs(b,a)9、Fs=2000;wc=100 200/(Fs/2);N=10;b,a=butter(N,wc,z);%freqz(b,a)dimpulse(b,a,100)10、wp=100;ws=200;rp=2;rs=15;Fs=500;wp=wp/(Fs/2);ws=ws/(Fs/2);N,wc=buttord(wp,ws,rp,rs);b,a=butter(N,wc,z)freqz(b,a)11、b=fir1(48,0.35 0.65);a=1;freqz(b,a)12、b=f

15、ir1(37,0.3);a=1;freqz(b,a)13、低通：F=0:1/56:1;A=ones(1,50),zeros(1,56-49);b=fir2(56,F,A);a=1;freqz(b,a)帶通：F=0:1/56:1;A=ones(1,25),zeros(1,25),ones(1,7);b=fir2(56,F,A);a=1;freqz(b,a)高通F=0:1/56:1;A=zeros(1,50),ones(1,56-49);b=fir2(56,F,A);a=1;freqz(b,a)%濾波器設計（橢圓濾波器）wp1=300;wp2=700;ws1=301;ws2=699;rp=0.1;

16、rs=50;Fs=2000;wp=wp1/(Fs/2);ws=ws1/(Fs/2);N,wc=ellipord(wp,ws,rp,rs,z)b,a=ellip(N,rp,rs,wc,high) %濾波器特性分析 freqz(b,a)%信號采樣及時頻變換Fs=2000;t=0:1/Fs:10;yt=sin(2*pi*200*t)+sin(2*pi*500*t)+sin(2*pi*800*t);figure(2);subplot(3,1,1);plot(t,yt)figure(2);subplot(3,1,2);plot(t,yt);axis(0,0.1,-5,5)yf=abs(fft(yt);f=(1:length(yf)