Learn To Program: Matlab

You can build a Java application using Matlab:

>> java

>> f = javax.swing.JFrame('A Java Application');

>> f.setSize(400,300);

>> f.setLocation(200, 100);

>> f.setVisible(true);

Then you can add some attribute

>> layout = java.awt.FlowLayout();

>> f.getContentPane().setLayout(layout);

>> bExit = javax.swing.JButton("Exit");

>> f.getContentPane().add(bExit);

Firstly, type this code and then save it - addTwo.m

function output = addTwo(input)

% This function will add the input with 2

output = 2 + input;

In Matlab interactive mode, type:

>> addTwo(3)

ans 5 

The function also can have more than one input and output arguments. Save this code to addThen.m:

function [add,dot] = addThen(input)

% This function will add and also will multiply 

% the input arguments.

add = input + input; 

dot = input * input;

Then in Matlab IDE, type

>> [a,b] = addThen(4)

a = 8

b = 16

Type to test:

>> sleep = true;

>> if sleep

disp('Do sleep');

end

Do sleep

>> a = 2; 

>> if a>3

disp('Nothing');

else

disp('Do sleep')

end

Do sleep

For do looping in Matlab, type:

>>  for i=0:20    % do looping for 0 till 20

disp(i)

end

>> for i=0:2:20   % do looping for 0  till 20 step 2

disp(i)

end

For while looping, do:

>> i = 0;

 >> while (i<10)

disp(i)

 i = i + 1;

end

To create a graphics, type:

>> figure

>> x = 0:0.1:2*pi;

>> y = sin(x);

>> plot(x, y);

Miscelaneous commands:

>> close       % Close the active graphics window

>> close all   % Close the graphics window

>> clf         % Clear the window from the graph

>> hold on     % Keep the line in the previous display

>> hold off    % Lose the line in the previous display

>> grid        % Toggle for grid

>> cla         % Clear axis

>> box         % Toggle box
>> rotate3d    % Make the graph so can moving like a 3D objects

Creating a matrix by type:

>> data = [2 3;

           4 5;

           8 3];

>> max(data)   

8 5

>> min(data)

2 3

>> mean(data)

4.6667 3.6667

>> median(data)

4 3

>> sort(data)

2 3

4 3

8 5

>> sum(data)

14 11

>> data<5

1 1

1 0

0 1

To create a matric, type:

>> data = [1 2;

           3 4]  

>> data(1,2) % Get the cross of the 1st row and the 2nd column

2 % var(row, col)

>> data(end,end) % Get the end of row and column

>> data(1:2,1) % Get elements cross at rows 1 till 2 and col 1

>> data(1:2,1:2) % Get rows 1 till 2 and col 1 till 2

1 2                % var(r1:r2, c1:c2)

3 4 % r1:r2 = row1 till row2

>> data(:,1)    % Get all rows at col 1

1

3

>> data(1,:) % Get all rows at row 1
1 2

>> data(:) % Get all elements in consecutive order

Detele rows or columns:

>> data(1,:)    % Delete all elements at the first row

>> data(:,1) % Delete all elements at the first column

Generating built in matric style:

>> zeros(r,c)    % Creating zero matrix by r and c dimension

>> magic(d)      % Creating random matrix by d and d dimension

>> ones(r,c)     % Creating 1 matrix by r and c dimension

>> rand(r,c)     % Creating random matrix by r and c dimension

>> randn(r,c)    % Creating random matrix (negative included) 

                 % by r and c dimension

>> eye(d) % Creating a diagonal matrix

In Matlab, data structure vector and matrix:

>> id = [4 5 6 2 4]

4 5 6 2 4 

>> id = 1:5    % start:end

1 2 3 4 5

>> id = 1:2:10    % start:step:end

1 3 5 7 9

How to access elements in matrix:

>> id = [4 5 6 7 8]

4 5 6 7 8

>> id(1)    % Get the 1st element of the id

4

>> id([1 2 3])    % Get the 1st, 2nd, 3rd elements of id

4 5 6 

>> id(1:3)    % Get the 1st till the 3rd elements

4 5 6

>> id(end) % Get the last element
8

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