Catalogue of series articles
Are there any students who have not learned the language matlab like me, but want to learn the course of intelligent optimization algorithm and matlab examples.
Article catalog
- Basic understanding
- Relation and logical operation
- Data input and output
- Select and loop statements
- Function file
- Matlab drawing
preface
The following is my summary of some basic matlab programming, I hope it can be helpful to you.
1, Basic understanding
(1) M file
m files have a. m extension.
M files can be divided into two types according to different calling methods:
Script: script file / command file
Function: function file
(2) Establishment and opening of M file
Create a new M file
Menu operation (File, New, File)
Command operation (edit M file name)
Command button (shortcut key)
Open an existing M file
Menu operation ( File ,Open )
Command operation (edit M file name)
Command button (shortcut key)
Double click the M file
M file control flow
2, Relation and logical operation
1. Relational operators
< (less than) > (greater than) = = (equal to) <= (less than or equal to) >= (greater than or equal to) ~= (not equal to)
The relational operator can be used to compare two arrays of the same size, or to compare an array with a scalar. In the latter case, the scalar is compared with each element in the array, and the comparison result is the same as the size of the array.
2. Logical operators
&(and ) | (or) ~ (non) xor(x,y) (XOR)
3, Data input and output
(1) Data input
A = input (prompt)
The prompt message is A string, This command requires the user to enter the value of A (which can be A number or A string)
eg. A=input('Please input A: ')
If it is an input string, you can also use the following method
A = input (prompt message,'s')
Note: do not add single quotation marks to the input string at this time!
eg. name=input('What''s your name? ', 's')
A=input('Please input A: ') name=input('What''s your name? ', 's') %%%%%%%result%%%%%%%%%% Please input A: 4 A = 4 What's your name? qingyun name = 'qingyun'
(2) Output of data: disp
disp(X)
The value of the output variable X can be a numeric matrix or a string
name=input('What''s your name? ', 's') disp(name) %%%%%%result%%%%%% What's your name? qingyun name = 'qingyun' qingyun
A='Hello,everyone !'; disp(A) %%%%%%%result%%%%%%% >> jichu Hello,everyone !
4, Select and loop statements
(1) if conditional statement
Single branch structure
if expression ((condition) statements (Statement group) end
sum=0; for i=1:100 sum=sum+i; end disp(sum) %%%%%%%%%result%%%%%% 5050
Double branch structure
if expression ((condition) statements1(Statement group 1) else statements2(Statement group 2) end
x=input('Please input x: ') if(x<0) disp('YES') else disp('NO') end %%%%%%%result%%%%%%% Please input x: 3 x = 3 NO
Multi branch structure
if expression1 (Condition 1) statements1(Statement group 1) elseif expression2 (Condition 2) statements2(Statement group 2) ... ... elseif expressionm (condition m) statementsm(Statement group m) else statements(Statement group) end
x=input('Please input x: ') if(x==1) disp('YES') elseif(x==2) disp('NO') else disp('I need to think about it') end %%%%%%result%%%%%% Please input x: 3 x = 3 I need to think about it
(2) Cyclic structure
for loop
for variable=expression statement(Circulation body) end
x = 0; for i = 1:100 x = x + i; end disp(x) %%%%%%result%%%%% >> jichu 5050
s = 0; for i = 1:2:100 %%%2 Is the step size s = s + i; end disp(s) %%%%%%%%%result%%%%% >> jichu 2500
while loop
while expression ((condition) statement(Circulation body) end
s = 0; k = 0; while(k <= 100) s = s + k; k = k + 1; end disp(s) %%%%%%result%%%%% >> jichu 5050
Other flow control statements
break and continue
The break statement is used to terminate the execution of the loop, that is, to jump out of the innermost loop The continue statement is used to end this cycle and proceed to the next cycle Break and continue are generally used with if statements
return
The return statement is used to exit a running script or function. It is usually used in the function file.
switch statement
Execute different statements according to different values of the expression.
switch expression ((expression) case value1 (Expression 1) statement1(Statement group 1) case value2 (Expression 2) statement2(Statement group 2) ... ... case valuem (expression m) statementm(Statement group m) otherwise statement (Statement group) end
sentence | effect |
---|---|
max(A,[],2) | Find the maximum value of each row in the matrix |
min(A,[],2) | Find the minimum value of each row in the matrix |
max(A,[],1) | Find the maximum value of each column in the matrix |
min(A,[],1) | Find the minimum value of each column in the matrix |
5, Function file
The function file is guided by a function statement
function [out1,out2,...] = function name (in1,in2,...)
%Note description section (optional)
Function body statement (required)
The first line is the leading line, indicating that the M file is a function file The naming rules of function names are the same as variable names (must start with letters) When there is more than one output line parameter, enclose it in square brackets
General format for function calls
Output argument list = function name (input argument list)
Subfunction
function avg = fun(x) % Main function n = length(x); avg = mean(x, n); function a = mean(x, n) % Subfunction a = sum(x)/n;
Six, Matlab drawing
Commonly used
%%%%%%%%%%%Drawing%%%%%%%%% figure x = 0:pi/100:2*pi; %%%0 To 2 pi,In the middle pi/100 Take points for spacing x Take 0 respectively, pi/100,2pi/100,3pi/100.......2*pi y = sin(x); plot(x,y) title('Qingyun Pavilion') xlabel('propitious clouds bringing well-being to all') ylabel('Qingyun studio')
basic form
plot(x,y)
x. If y is a vector, take the element in X as the abscissa and the element in y as the ordinate to make a plane curve. At this time, X and y must have the same length.
x. If y is a matrix, the columns of X and the corresponding columns in y are combined to draw multiple plane curves. At this time, X and y must have the same size.
x is a vector and Y is a matrix. If the length of x is equal to the number of rows of Y, the columns in x and y are corresponding to draw multiple plane curves; otherwise, if the length of x is equal to the number of columns of Y, the rows in x and y are corresponding to draw multiple plane curves. At this time, the length of x must be equal to the number of rows or columns of Y.
Properties of the drawing
Basic properties of points and lines
plot(x,y,string)
Where string is a string enclosed in single quotation marks, which is used to specify the attributes of the graph (the shape and color of points and lines)
>> x=[0:0.2:2*pi]; >> plot(x,cos(x)); >> plot(x,cos(x),'r+:'); >> plot(x,cos(x),'bd-.'); >> plot(x,cos(x),'k*-');
Draw multiple function images at the same time
plot(x1,y1,s1,x2,y2,s2, ... ,xn,yn,sn)
Equivalent to:
hold on plot(x1,y1,s1) plot(x2,y2,s2) ... plot(xn,yn,sn)
Basic properties of graphics
b blue Blue . point - solid
g green Green o circle : dotted
r red Red x x-mark -. dashdot
c cyan Green + plus -- dashed
m Magenta magenta * star (none) no line
y Yellow yellow s square
k black Black d diamond
w white White v triangle (down)
^ triangle (up)
< triangle (left)
> triangle (right)
p pentagram Pentagram
h hexagram Hexagonal star
Additional properties of the drawing
title
title('text')
Axis dimension
xlabel('text ') or ylabel(’text’)
Add legend
legend(string1,string2, ...)
Other related commands
show grid
grid on or grid off
Keep the image of the current window
hold on or hold off
New drawing window
figure(n)