MATLAB 二维三维画图 仿真 数组运算

1.数学

（1）数组运算；

x=[1 2 3 4];

y=[3 4 5 6];

z=x+y %数组x与数组y相加得到数组z

z =

4 6 8 10

z=x-y %数组x与数组y相减得到数组z

z =

-2 -2 -2 -2

z=x.*y %数组x与数组y相乘得到数组z

z =

3 8 15 24

z=x./y %数组x与数组y相除得到数组z

z =

0.3333 0.5000 0.6000 0.6667 （2）矩阵及其运算

a=[1 2 3 4;2 3 4 5;3 4 5 6]

a=

1 2 3 4

2 3 4 5

3 4 5 6

a1=a' %矩阵的转置

a1 =

1 2 3

2 3 4

3 4 5

4 5 6

b=[1 2 3;4 5 6;7 8 9];

c=[12 34 44;2 3 5;6 7 8];

d=b+c %矩阵的相加

d =

13 36 47

6 8 11

13 15 17

e=b-c %矩阵的相减

e =

-11 -32 -41

2 2 1

1 1 1

A=b*c %矩阵的相乘

A =

34 61 78

94 193 249

154 325 420

A=c*b %矩阵的相乘

A =

456 546 636

49 59 69

90 111 132

A=[1 12 7;3 8 5;4 3 6];

B=[4;9;13];

C=A\B %矩阵的左除

C =

2.6442

-0.1731

0.4904

B=flipud(A) %矩阵B由矩阵A上下翻转得到

B =

4 3 6

3 8 5

1 1

2 7

C=A/B %矩阵的右除

C =

0 0 1

0 1 0

1 0 0

D=A^2 %矩阵A的二次方

D =

65 129 109

47 115 91

37 90 79

（3）函数及其运算

x=0:pi/100:2*pi;

y=sin(x);

plot(x,y) %正弦函数

(4)数值分析

%数值积分

d=pi/100;

t=0:d:3*pi;

nt=length(t);

y=exp(-0.5*t).*sin(t+pi/6);

z=trapz(y)*d

z =

0.9008

sc=cumsum(y)*d;

scf=sc(nt)

scf =

0.9086

(5)数据分析

统计计算

randn('seed',0);

a=randn(100,5);

a_max=max(max(a))

a_max =

3.2069

a_end=median(a)

a_end =

0.1489 0.0301 0.0443 -0.0189 0.1375 a_mean=mean(a)

a_mean =

0.0727 0.0264 0.0351 0.0424 0.0752 a_prod=prod(a)

a_prod =

1.0e-020 *

-0.0000 0.1268 -0.0000 -0.0000 0.0007 2.图形技术

（1）平面绘图

x=0:0.4:4*pi;

y1=exp(-0.1*x).*sin(x);

y2=exp(-0.1*x).*sin(x+1);

plot(x,y1,x,y2) %绘制两条曲线

x=(0:pi/45:2*pi)';

k=0.3:0.1:1;

y=cos(x)*k;

plot(y) %绘制多条不同色彩的曲线

x=0:0.01:20;

y1=200*exp(-0.5*x).*sin(x);

y2=0.8*exp(-0.5*x).*sin(10*x);

plotyy(x,y1,x,y2); %绘制双纵坐标图

(2)立体绘图（三维）

[X,Y]=meshgrid(-10:0.5:10);

B=sqrt(X.^2+Y.^2)+eps;

Z=cos(B)./B;

mesh(X,Y,Z); %绘制三维曲面网线

[X,Y]=meshgrid(-2:0.2:2);

Z=X.*exp(-X.^2-Y.^2);

plot3(X,Y,Z); %绘制多条三维曲线

[X,Y]=meshgrid(-10:0.5:10);

B=sqrt(X.^2+Y.^2)+eps;

Z=sin(B)./B;

surf(X,Y,Z); %绘制三维曲面

(3)绘制子图

x=pi*(0:1000)/1000;

y1=sin(x);

y2=sin(10*x);

y12=y1.*y2;

subplot(221);plot(x,y1);axis([0,pi,-1,1]); %分割并绘制第一幅子图subplot(222);plot(x,y2);axis([0,pi,-1,1]); %分割并绘制第二幅子图subplot('position',[0.2,0.05,0.6,0.45]); %分割第三幅子图的位置plot(x,y12);axis([0,pi,-1,1]); %绘制第三幅子图

（4）图形标志

x=0:2*pi/90:2*pi;

y1=sin(2*x);

y2=exp(-15*x).*sin(2*x);

plot(x,y1,'r:',x,y2,'m*');

legend('第一条','第二条')

3.程序设计

(1)控制流

1)while语句

num=0;EPS=1;

while(1+EPS)>1

EPS=EPS/2;

num=num+1;

end

num

EPS=2*EPS

num =

53

EPS =

2.2204e-016

2）if语句

n=input('n?');

if rem(n,2)==0

disp('n is even');

end

输入6，得到结果得到n is even

3)for语句

for i=1:4

for j=1:3

a(i,j)=i*j;

end

end

a

a =

1 2 3

2 4 6

3 6 9

4 8 12

4)switch语句

var=input('var=?');

switch var

case 1

disp('var=1');

case {2,3,4}

disp('var=2 or 3 or 4');

case 5

disp('var=5');

otherwise

disp('other value');

end

(2)M文件

1）命令文件

prime %{新建一个prim.m的文件，程序如下

%clear;

%close all

%N=input('N=\n');

%x=2:N;

%for u=2:sqrt(N)

%n=find(rem(x,u)==0 & x~=u);

%x(n)=[];

%end;

%x }

function[out1,out2]=humps(x)

if nargin==0

x=0:0.05:1;

end

y=1./((x-0.3).^2+0.1)+1./((x-0.9).^2+0.4)-6;

if nargout==2

out1=x;

out2=y;

else

out1=y;

end

%运行后输入N数值，如输入35得到结果是x=2 3 5 7 11 13 17 19 23 29 31 2）函数文件

fun1

%function z=fun1(x,y)

%global abpha beta

%m=length(x);

%n=length(y);

%x1=x'*ones(1,n);

%y1=(y'*ones(1,m))';

%z=alpha*(x1-1).^2+beta*(y1+1).^2;

fun11 %global alpha beta

%u=[0:0.02:2];

%v=[-2:0.02:0];

%figure(1)

%subplot(211);

%alpha=1;beta=1;

%w=fun1(u,v);

%mesh(w);

%title(['\alpha=',num2str(alpha),'and\beta=',/num2str(beta)]);

%subplot(212);

%alpha=2;beta=2;

%w=fun1(u,v);

%mesh(w);

%title(['\alpha=',num2str(alpha),'and\beta=',/num2str(beta)]);

function y = mean(x,dim)

%MEAN Average or mean value.

% For vectors, MEAN(X) is the mean value of the elements in X. For % matrices, MEAN(X) is a row vector containing the mean value of

% each column. For N-D arrays, MEAN(X) is the mean value of the

% elements along the first non-singleton dimension of X.

%

% MEAN(X,DIM) takes the mean along the dimension DIM of X.

%

% Example: If X = [0 1 2

% 3 4 5]

%

% then mean(X,1) is [1.5 2.5 3.5] and mean(X,2) is [1

% 4]

%

% Class support for input X:

% float: double, single

%

% See also MEDIAN, STD, MIN, MAX, VAR, COV, MODE.

% Copyright 1984-2005 The MathWorks, Inc.

% $Revision: 5.17.4.3 $ $Date: 2005/05/31 16:30:46 $

if nargin==1,

% Determine which dimension SUM will use

dim = min(find(size(x)~=1));

if isempty(dim), dim = 1; end

y = sum(x)/size(x,dim);

else

y = sum(x,dim)/size(x,dim);

end

4.S imulink

1).用Simulink实现两个正弦信号的乘积，即计算想x(t)=sin(2t)*sin(5t),

并显示输出波形

AT

2).用Simulink输出传递函数的波形

simulink1

simulink2

simulink3

num0=[40]

p1=[1,0]

p2=[0.25,1]

p3=[0.0625,1]

p=conv(p1,p2)

den0=conv(p,p3)

rlocus(num0,den0)

k=40/(0.25*0.0625);

[pj,k]=rlocus(num0,den0,k)

figure(2)

bode(num0,den0)

grid

[m,fai,wg,wc]=margin(num0,den0)

h=20*log10(m)

num0 =

40

p1 =

1 0

p2 =

0.2500 1.0000

p3 =

0.0625 1.0000

p =

0.2500 1.0000 0

den0 =

0.0156 0.3125 1.0000 0

pj =

1.0e+002 *

-1.9393 0.8696 + 1.6196i 0.8696 - 1.6196i k =

2560

Warning: The closed-loop system is unstable.

> In warning at 26

In lti.margin at 66

In margin at 98

m =

0.5000

fai =

-15.0110

wg =

8.0000

wc =

11.1190

h =

-6.0206

num0=[40*4 40]

p1=[1,0]

p2=[80,1]

p3=[0.25,1]

p4=[0.0625,1]

p12=conv(p1,p2)

p123=conv(p12,p3)

den0=conv(p123,p4)

figure(5)

rlocus(num0,den0)

k=40*4/(80*0.25*0.0625);

[pj,k]=rlocus(num0,den0,k) figure(6)

bode(num0,den0)

grid

[m,fai,wg,wc]=margin(num0,den0) h=20*log10(m)

num0 =

160 40

p1 =

1 0

p2 =

80 1

p3 =

0.2500 1.0000

p4 =

0.0625 1.0000

p12 =

80 1 0

p123 =