matlab课后作业 北交大 钱满义

第二单元

M2-1

（1）

>> t=-5:0.01:5; x=(t>0)-(t>2); plot(t,x);

axis([-5,5,-2,2]);

21.510.50-0.5-1-1.5-2-5-4-3-2-1012345

（2）

t=-5:0.01:5; >> x=(t>0); >> plot(t,x);

>> axis([-5,5,-2,2]);

21.510.50-0.5-1-1.5-2-5-4-3-2-1012345

(3)

t=-1:0.01:10;

>> x=10*exp(-t)-5*exp(-2*t); >> plot(t,x);

50-5-10-20246810

（4）

t=-1:0.01:10; >> x=t.*(t>0); >> plot(t,x);

109876543210-20246810

(5)

t=-10:0.001:10;

>> pi=3.14;x=2*abs(sin(10*pi*t+pi/3)); >> plot(t,x);

21.81.61.41.210.80.60.40.20-10-8-6-4-20246810

(6)

t=-10:0.001:10;

>> x=cos(t)+sin(2*pi*t); >> plot(t,x);

21.510.50-0.5-1-1.5-2-10-8-6-4-20246810

(7)

>> t=-10:0.001:10; pi=3.14;

>> x=4.*exp(-0.5.*t).*cos(2.*pi*t); plot(t,x);

6004002000-200-400-600-10-8-6-4-20246810

(8)

t=-10:0.001:10; >> pi=3.14;

x=sin(pi*t)./(pi*t).*cos(30*t); >> plot(t,x);

10.80.60.40.20-0.2-0.4-0.6-0.8-1-2-1.5-1-0.500.511.52

五

（1） x[k]=delta[k] k=-50:50;

>> delta=[zeros(1,50),1,zeros(1,50)]; >> stem(k,delta)

10.90.80.70.60.50.40.30.20.10-50-40-30-20-1001020304050

（2） x[k]=u[k] >> k=-50:50;

uk=[zeros(1,50),ones(1,51)]; stem(k,uk)

10.90.80.70.60.50.40.30.20.10-50-40-30-20-1001020304050

(3) k=-50:50;

>> xk=10*(0.5.^k).*[zeros(1,50),ones(1,51)]; >> stem(k,xk)

109876543210-50-40-30-20-1001020304050

(4) k=-50:50;

>> xk=[zeros(1,48),ones(1,7),zeros(1,46)]; >> stem(k,xk)

10.90.80.70.60.50.40.30.20.10-50-40-30-20-1001020304050

(5) k=-50:50;

uk=k.*[zeros(1,50),ones(1,51)]; stem(k,uk)

50454035302520151050-50-40-30-20-1001020304050

(6)

k=-50:50;

>> xk=5.*(0.8.^k).*cos(0.9*pi.*k).*[ones(1,101)]; >> stem(k,xk)

3x 105210-1-2-3-4-50-40-30-20-1001020304050

M2-6 W=0.1pi k=-50:50; >> w=0.1*pi; >> xk=sin(w.*k); >> stem(k,xk);

10.80.60.40.20-0.2-0.4-0.6-0.8-1-50-40-30-20-1001020304050

W=0.5pi k=-50:50; >> w=0.5*pi; >> xk=sin(w.*k); >> stem(k,xk);

10.80.60.40.20-0.2-0.4-0.6-0.8-1-50-40-30-20-1001020304050

W=0.9pi k=-50:50; >> w=0.9*pi; >> xk=sin(w.*k); >> stem(k,xk);

10.80.60.40.20-0.2-0.4-0.6-0.8-1-50-40-30-20-1001020304050

W=1.1pi k=-50:50; >> w=1.1*pi; >> xk=sin(w.*k); >> stem(k,xk);

10.80.60.40.20-0.2-0.4-0.6-0.8-1-50-40-30-20-1001020304050

W=1.5pi k=-50:50; >> w=1.5*pi; >> xk=sin(w.*k); >> stem(k,xk);

10.80.60.40.20-0.2-0.4-0.6-0.8-1-50-40-30-20-1001020304050

W=1.9pi k=-50:50; >> w=1.9*pi; >> xk=sin(w.*k); >> stem(k,xk);

21.510.50-0.5-1-1.5-2-2-1.5-1-0.500.511.52>> k=-6:5;

>> x=[-3,-2,3,1,-2,-3,-4,2,-1,4,1,-1]; >> stem(k,x)

43210-1-2-3-4-6-4-20246>> k=-2:9;

>> x=[-3,-2,3,1,-2,-3,-4,2,-1,4,1,-1]; >> stem(k,x)

43210-1-2-3-4-20246810>> k=-4:7;x=[-3,-2,3,1,-2,-3,-4,2,-1,4,1,-1]; >> xk=fliplr(x); >> k1=-fliplr(k); >>stem(k1,xk)

43210-1-2-3-4-8-6-4-2024

第三单元

1）>> ts=0;te=5;dt=0.01; >> sys=tf([2 1],[1 3 2]); >> t=ts:dt:te;

>> x=exp(-3*t).*(t>=0); >> y=lsim(sys,x,t); >> plot(t,y);

>> xlabel('Time(sec)') >> ylabel('y(t)')

0.30.250.20.15y(t)0.10.050-0.05012Time(sec)345

>> ts=0;te=5;dt=0.0001; >> sys=tf([2 1],[1 3 2]); >> t=ts:dt:te;

>> x=exp(-3*t).*(t>=0); >> y=lsim(sys,x,t); >> plot(t,y);

>> xlabel('Time(sec)') >> ylabel('y(t)')

0.30.250.20.15y(t)0.10.050-0.05012Time(sec)345

4）x=[0.85,0.53,0.21,0.67,0.84,0.12]; k1=-2:3;

h=[0.68,0.37,0.83,0.52,0.71]; k2=-1:3; y=conv(x,h);

k=(k1(1)+k2(1)):(k1(end)+k2(end)); stem(k,y);

-1.3140 -18.5860i k =

[]

>> [angle,mag]=cart2pol(real(r),imag(r))

angle =

-1.5054 1.5054 1.6462 -1.6462

mag =

1.5180 1.5180 1.3175

1.3175

X(s)=1.5180*exp(j*2.6258)/(s+1.5145-j*21.4145)+1.5180*exp(-j*2.6258)/(s+1.5145+j*21.4145)+ 1.3175*exp(j*1.6462)/(s+1.3140-j*18.5860)+ 1.3175*exp(-j*1.6462)/(s+1.3140+j*18.5860) x(t)=0.1984*exp(-1.5145*t)cos(21.4145t)u(t)-3.0294*exp(-1.5145*t)sin(21.4145t)u(t)-0.1984exp*(-1.3140*t)cos(18.5860*t)u(t)2.6274*exp*(-1.3140*t)sin((18.5860*t)u(t) 1_(3)

>> num=[1 0 0 0];

>> den=conv([1 5],[1 5 25]); >> [r,p,k]=residue(num,den) r =

-2.5000 - 1.4434i -2.5000 + 1.4434i -5.0000 p =

-2.5000 + 4.3301i -2.5000 - 4.3301i -5.0000

k =

1

>> [angle,mag]=cart2pol(real(r),imag(r))

angle =

-2.6180 2.6180 3.1416

mag =

2.8868 2.8868

5.0000

X(s)=1+2.8868*exp(-j*2.6180)/(s+2.5-j* 4.3301)+2.8868*exp(j*2.6180)/(s+2.5+j*4.3301)+5/(s+5) X(t)=δ（t）-5*exp(-2.5*t)cos(4.3301*t)u(t)-2.8868*exp(-2.5*t)sin(4.3301*t)u(t)-5*exp(-5*t)u(t)

M6-2

对微分方程两边进行单边laplace变换，得

整理后，得

所以

零输入响应

MATLAB程序如下 >> num=[1 6]; >> den=[1 4 3];

>> [r,p,s]=residue(num,den) r =

-1.5000

2.5000 p =

-3 -1 s =

[] 由此可得所以

MATLAB 程序如下 >> num=[2 1];

>> den=conv([1 0],[1 4 3]); >> [r,p,k]=residue(num,den) r =

-0.8333 0.5000 0.3333 p =

-3 -1 0

k =

[] 所以

所以

图形输出MATLAB程序如下

>> t=0:0.001:10; >> ut=(t>=0);

>> yzi=(2.5*exp(-t)-1.5*exp(-3*t)).*ut; >> yzs=(0.5*exp(-t)-0.8333*exp(-3*t)).*ut; >> yt=yzi+yzs; >> subplot(2,1,1)

>> plot(t,yzi,'b',t,yzs,'r'); >> subplot(2,1,2) >>

plot(t,yt)

1.510.50-0.50123456789101.510.50012345678910

M6-5

>> num=[1 2]; >> den=[1 2 2 1]; >> sys=tf(num,den); >> figure(1);pzmap(sys); t=0:0.02:10; >> w=0:0.02:5;

>> h=impulse(num,den,t); >> figure(2);plot(t,h); >> xlabel('times(s)');

>> title('Impulse Respone') >> t=0:0.02:10; >> w=0:0.02:5;

>> h=step(num,den,t); >> figure(3);plot(t,h); >> title('阶跃相应') >> H=freqs(num,den,w); >> figure(4);plot(w,abs(H)) >> xlabel('Frequency\\omega'); >> title('Magnitude Respone'); >> plot(w,angle(H))

本文来源：https://www.bwwdw.com/article/xq1g.html