matlab参考资料

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1-3.(1)Abc, wu_2004,是合法的;2004x, li1-1, a&b, qst.u, _ xyz是不合法的。

1-4.(1)[12+2*(7-4)]/3^2

ans = 2

(2)>> A=[1,2,3;4,5,6;7,8,9]

A =

1 2 3

4 5 6 7 8 9

(3) >> clear;x=-8:0.5:8;

y=x';

X=ones(size(y))*x;

Y=y*ones(size(x)); R=sqrt(X.^2+Y.^2)+eps;

Z=sin(R)./R;

mesh(X,Y,Z);

colormap(hot)

xlabel('x'),ylabel('y'),zlabel('z') >>

1-11

2-1.

2-2. >> x1=0:pi/25:2*pi

x1 =

Columns 1 through 8

0 0.1257 0.2513 0.3770 0.5027 0.6283 0.7540 0.8796

Columns 9 through 16

1.0053 1.1310 1.2566 1.3823 1.5080 1.6336 1.7593 1.8850

Columns 17 through 24

2.0106 2.1363 2.2619 2.3876 2.5133 2.6389 2.7646 2.8903

Columns 25 through 32

3.0159 3.1416 3.2673 3.3929 3.5186 3.6442 3.7699 3.8956

Columns 33 through 40

4.0212 4.1469 4.2726 4.3982 4.5239 4.6496 4.7752 4.9009

Columns 41 through 48

5.0265 5.1522 5.2779 5.4035 5.5292 5.6549 5.7805 5.9062

Columns 49 through 51

6.0319 6.1575 6.2832

>> x2=linspace(0,2*pi,50)

x2 =

Columns 1 through 8

0 0.1282 0.2565 0.3847 0.5129 0.6411 0.7694 0.8976

Columns 9 through 16

1.0258 1.1541 1.2823 1.4105 1.5387 1.6670 1.7952 1.9234

Columns 17 through 24

2.0517 2.1799 2.3081 2.4363 2.5646 2.6928 2.8210 2.9493

Columns 25 through 32

3.0775 3.2057 3.3339 3.4622 3.5904 3.7186 3.8468 3.9751

Columns 33 through 40

4.1033 4.2315 4.3598 4.4880 4.6162 4.7444 4.8727 5.0009

Columns 41 through 48

5.1291 5.2574 5.3856 5.5138 5.6420 5.7703 5.8985 6.0267

Columns 49 through 50

6.1550 6.2832

2-3. t=0:pi/5:2*pi;

y=exp(-2*t).*sin(t)

y =

Columns 1 through 8

0 0.1673 0.0770 0.0219 0.0039 0.0000 -0.0003 -0.0001

Columns 9 through 11

-0.0000 -0.0000 -0.0000

2-4. A=[1,2;3,4];B=[5,6;7,8]; X=A*B

Y=A.*B

X =

19 22

43 50

Y =

5 12

21 32

2-5. A=[1 2 3 4;1 3 5 0];B=[1 0 5 3;1 5 0 5];

C=A&B D=A|B

E=~A

F=(A==B)

G=(A>B)

C =

1 0 1 1

1 1 0 0

D =

1 1 1 1 1 1 1 1

E =

0 0 0 0

0 0 0 1

F =

1 0 0 0

1 0 0 0

G =

0 1 0 1

0 0 1 0

2-7. A=[1 2 3 4;1 3 5 0]; B=num2str(A)

size(A)

size(B)

B =

1 2 3 4

1 3 5 0

ans =

2 4

ans =

2 10

3-1. t=0:0.02:18;

xi1=0.2; beta1=sqrt(1-xi1^2); sita1=atan(beta1/xi1);

y1=1-exp(-xi1*t).*sin(beta1*t+sita1)*(1/beta1);

plot(t,y1,'b'),hold on xi2=0.4;

beta2=sqrt(1-xi2^2);

sita2=atan(beta2/xi2);

y2=1-exp(-xi2*t).*sin(beta2*t+sita2)*(1/beta2);

plot(t,y2,'b'),hold on xi3=0.6;beta3=sqrt(1-xi3^2);sita3=atan(beta3/xi3);

y3=1-exp(-xi3*t).*sin(beta3*t+sita3)*(1/beta3);

plot(t,y3,'r'),hold on

xi4=0.8;beta4=sqrt(1-xi4^2);sita4=atan(beta4/xi4);

y4=1-exp(-xi4*t).*sin(beta4*t+sita4)*(1/beta4); plot(t,y4,'c'),hold on

xlabel('t/s'),ylabel('y')

text(3.5,0.9,'{\xi}=0.8'),text(5.4,1.5,'{\xi}=0.2')

3-2. x=-4:4;y=x;

[X,Y]=meshgrid(x,y); Z=1./(sqrt((1-X).^2+Y.^2)+sqrt((1+X).^2+Y.^2));

subplot(1,3,1),surf(X,Y,Z);

subplot(1,3,2),mesh(X,Y,Z);

subplot(1,3,3),plot3(x,y,1./(sqrt((1-x).^2+y.^2)+sqrt((1+x).^2+y.^2)));box on

3-3. t=(0:0.02/pi:30*pi);

x=sin(t);y=cos(t);z=t;

plot3(x,y,z,'g') box on

习题4

1. 请分别用for和while循环语句计算

63

02

iiK的程序,再写出一种避免循环的计算程序(提示:可考虑利

用MATLAB中的sum(X,n)函数,实现沿数组X的第n维求和)

答:for语句程序及输出结果:

clear;k(1)=1;

for i=0:62

k(i+2)=k(i+1)+2^(i+1);

i=i+1;

end;

i,k(i+1)

>> i =

63

ans =

1.8447e+019

while语句程序及输出结果:

clear;k(1)=1;i=0

while i<=62

k(i+2)=k(i+1)+2^(i+1);

i=i+1;

end;

i,k(i+1)

i =

63

ans =

1.8447e+019

避免循环的计算程序及输出结果:

clear;i=(0:63);

m=linspace(1,1,64);

k=m.*pow2(i);

sum(k,2)

ans =

1.8447e+019

习题5

1将下列系统的传递函数模型用matlab语言表达出来。

(1) G1(s)=(s4+35s3+291s2+1093s+1700)/(s5+289s4+254s3+2541s2+4684s+1700);

(2) G2(s)=15(s+3)/(s+1)(s+5)(s+15);

(3) G3(s)=100s(s+2)2(s2+3s+2)/(s+1)(s-1)(s3+2s2+5s+2); 答:(1) >> sys1=tf([1,35,291,1093,1700],[1,289,254,2541,4684,1700])

Transfer function:

s^4 + 35 s^3 + 291 s^2 + 1093 s + 1700

-------------------------------------------------------------------------- s^5 + 289 s^4 + 254 s^3 + 2541 s^2 + 4684 s + 1700

(2) >> sys2=zpk(-3,[-1,-5,-15],15)

Zero/pole/gain:

15 (s+3) ------------------

(s+1) (s+5) (s+15)

(3) >> sys1=tf([1,3,2],[1,2,5,2]);

>> sys2=zpk([0,-2,-2],[1,-1],100);

>> sys3=sys1*sys2 Zero/pole/gain:

100 s (s+2)^3 (s+1)

----------------------------------------------

(s+1) (s+0.4668) (s-1) (s^2 + 1.533s + 4.284)

>> sys4=minreal(sys3)

Zero/pole/gain:

100 s (s+2)^3

----------------------------------------

(s-1) (s+0.4668) (s^2 + 1.533s + 4.284)