matlab tutorial

Sat, 22 Nov 2025 08:50:29 +0800

1.Basic Arithmetic

直接在命令行输入算式，结果存入ans变量中如：

>> 1+2

ans =

     3

2.Variables

设置变量的值，存入系统中，之后可以调用

>> x=7

x =

     7

>> x+3

ans =

    10

>>

3.Change Format

format [数据类型] 可以改变运算的结果数据类型

>> 1/3

ans =

    0.3333

>> format short
>> 1/3

ans =

    0.3333

>> format long
>> 1/3

ans =

   0.333333333333333

>>

4.Remove Variables

clear [变量名] 用于清楚变量

>> x

x =

     7

>> clear x
>> x
函数或变量 'x' 无法识别。
 
>>

5.Clear Specific Variables

高级一点的Remove Variables之类的用法


>> x3=3

x3 =

     3

>> 
>> clear x*
>> x3=3

x3 =

     3

>> who

您的变量为:

ans  x3   

>> whos
  Name      Size            Bytes  Class     Attributes

  ans       1x1                 8  double              
  x3        1x1                 8  double              

>>

6. Pre-Defined Constants

系统中预定义的变量

>> pi

ans =

   3.141592653589793

>> format short
>> pi

ans =

    3.1416

>> inf

ans =

   Inf

>> nan

ans =

   NaN

>> i

ans =

   0.0000 + 1.0000i

7. Operational Operators

操作运算符

>> 2>3

ans =

  logical

   0

>> 3>2

ans =

  logical

   1

>> 2>2

ans =

  logical

   0

>> 2>=2

ans =

  logical

   1

8. Built-In Functions

内置函数

>> sin(3.14)

ans =

    0.0016

>> cos(0)

ans =

     1

>> exp(1)

ans =

    2.7183

>> log(10)

ans =

    2.3026

>> abs(-2)

ans =

     2

>>

9. Vectors & Matrices

关于向量和矩阵的使用

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

a =

     1     2     3
     4     5     6
     7     8     9

>> whos
  Name      Size            Bytes  Class     Attributes

  a         3x3                72  double              
  ans       1x1                 8  double              
  x3        1x1                 8  double              

>> b=[1 2 3];
>> c=b'

c =

     1
     2
     3

>> whos
  Name      Size            Bytes  Class     Attributes

  a         3x3                72  double              
  ans       1x1                 8  double              
  b         1x3                24  double              
  c         3x1                24  double              
  x3        1x1                 8  double              

>>

10. Indexing

矩阵、向量的操作

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

a =

     1     2     3
     4     5     6
     7     8     9

>> b=a(:,1)

b =

     1
     4
     7

>> a(end,3)=0

a =

     1     2     3
     4     5     6
     7     8     0

>> a(end,:)=0

a =

     1     2     3
     4     5     6
     0     0     0

>> x=[1:5;6:9]
错误使用 vertcat
要串联的数组的维度不一致。
 
>> x=[1:5;6:10]

x =

     1     2     3     4     5
     6     7     8     9    10

>> a1=ones(1,size(a,1))

a1 =

     1     1     1
>> zeros(5)

ans =

     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0

>> zeros(1,5)

ans =

     0     0     0     0     0

>> eye(3)

ans =

     1     0     0
     0     1     0
     0     0     1

>> a(1,2)

ans =

     2

>> a(2,2)=10

a =

     1     2     3
     4    10     6
     0     0     0

11. Other Keywords

其他的一些关键字

>> length(a)

ans =

     3

>> size(a)

ans =

     3     3

>> numel(a)

ans =

     9

>> trace(a)

ans =

    11

>> eig(a)

ans =

    0.1849
   10.8151
         0

>> a

a =

     1     2     3
     4    10     6
     0     0     0

>> a=[1:3;4:6;7:9]

a =

     1     2     3
     4     5     6
     7     8     9

>> inv(a)
警告: 矩阵接近奇异值，或者缩放不良。结果可能不准确。RCOND =  1.541976e-18。 
 

ans =

   1.0e+16 *

   -0.4504    0.9007   -0.4504
    0.9007   -1.8014    0.9007
   -0.4504    0.9007   -0.4504

>> det(a)

ans =

   6.6613e-16

12. Matrix Operations

>> a=rand(5)

a =

    0.2760    0.4984    0.7513    0.9593    0.8407
    0.6797    0.9597    0.2551    0.5472    0.2543
    0.6551    0.3404    0.5060    0.1386    0.8143
    0.1626    0.5853    0.6991    0.1493    0.2435
    0.1190    0.2238    0.8909    0.2575    0.9293

>> b=rand(5)

b =

    0.3500    0.3517    0.2858    0.0759    0.1299
    0.1966    0.8308    0.7572    0.0540    0.5688
    0.2511    0.5853    0.7537    0.5308    0.4694
    0.6160    0.5497    0.3804    0.7792    0.0119
    0.4733    0.9172    0.5678    0.9340    0.3371

>> a+b

ans =

    0.6260    0.8500    1.0371    1.0351    0.9706
    0.8763    1.7906    1.0123    0.6012    0.8231
    0.9062    0.9256    1.2597    0.6694    1.2837
    0.7787    1.1350    1.0795    0.9285    0.2554
    0.5923    1.1410    1.4587    1.1915    1.2664
>> a>b

ans =

  5×5 logical 数组

   1   0   0   0   1
   1   1   1   1   0
   0   1   1   1   1
   1   1   0   0   1
   1   1   1   1   0
>> a.*b

ans =

    0.6173    0.0689    0.1298    0.0623    0.3212
    0.6731    0.0089    0.6744    0.1609    0.0159
    0.0498    0.1514    0.3035    0.7010    0.5488
    0.5987    0.0442    0.4612    0.6300    0.6625
    0.1083    0.0937    0.0276    0.1793    0.5122
>> a^2

ans =

    1.3164    0.9614    0.9676    1.0427    1.2492
    1.5213    1.1350    1.5754    1.5032    1.8462
    2.0937    2.3843    2.5910    2.6654    2.3472
    2.9873    2.2809    2.6699    2.5017    2.4191
    2.7964    2.3417    2.8111    2.6409    2.4855

>> a.^2

ans =

    0.6638    0.0095    0.0248    0.0201    0.4300
    0.8205    0.0776    0.9421    0.1779    0.0013
    0.0161    0.2991    0.9162    0.8386    0.7210
    0.8343    0.9168    0.2356    0.6276    0.8723
    0.3999    0.9310    0.6404    0.9206    0.4607

13. Solve System of Equations

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

a =

     1     2     3
     4     5     6
     7     8     9

>> b=[1 1 1]

b =

     1     1     1

>> a\b
错误使用  \ 
矩阵维度必须一致。
 
>> b=b'

b =

     1
     1
     1

>> a\b
警告: 矩阵接近奇异值，或者缩放不良。结果可能不准确。RCOND =  1.541976e-18。 
 

ans =

   -2.5000
    4.0000
   -1.5000
>> x=a\b
警告: 矩阵接近奇异值，或者缩放不良。结果可能不准确。RCOND =  1.541976e-18。 
 

x =

   -2.5000
    4.0000
   -1.5000

>> a*x

ans =

     1
     1
     1

14. M-File Scripts

matlab文件的使用

%% matlab tutorial
% December 2025

3 Magic C’s

%% matlab tutorial
% December 2025

clear all
close all
clc

15. Loops

%% matlab tutorial
% December 2025

clear all
close all
clc

counter=10;
% for i=1:5
%     counter=counter+1;
%     disp(counter)
% end

while counter>=5;
    counter=counter-1;
    disp(counter)
end

16. Plotting

%% matlab tutorial
% December 2025

clear all
close all
clc

counter=10;
% for i=1:5
%     counter=counter+1;
%     disp(counter)
% end

while counter>=5;
    counter=counter-1;
    disp(counter)
end


%% plotting

x=0:0.1:5;
y=x.^2;
plot(x,y,'r+')
title('my first plot')

xlabel('x_value')
ylabel('y_value')

grid on
hold
y2=x.^3;
y3=x.^4;
plot(x,y2,'g*')
plot(x,y3)
hold off
legend('plot1','plot2','plot3')

%% subplotting
subplot(311)
plot(x,y)
subplot(312)
plot(x,y2)
subplot(313)
plot(x,y3)

17. Functions

function a=triangle_area(w,h)
    a=0.5*w*h;
end

18. Debugging

可以设置断点，类似调试c/c++

Reference

Learn MATLAB in ONE Video!–by Jousef Murad | Deep Dive

Matlab on farmer3-c Blog