没办法，常常国外网站不能访问，转一下。
Abstract : Learn the basic features of Matlab, and learn how to load and visualize signals and images.
Basic Matlab commands.
- Create a variable and an array
% this is a comment
a = 1; a = 2+1i; % real and complex numbers
b = [1 2 3 4]; % row vector
c = [1; 2; 3; 4]; % column vector
d = 1:2:7; % here one has d=[1 3 5 7]
A = eye(4); B = ones(4); C = rand(4); % identity, 1 and random matrices
c = b'; % transpose - Modification of vectors and matrices
A(2,2) = B(1,1) + b(1); % to access an entry in a vector or matrix
b(1:3) = 0; % to access a set of indices in a matrix
b(end-2:end) = 1: % to access the last entries
b = b(end:-1:1); % reverse a vector
b = sort(b); % sort values
b = b .* (b>2); % set to zeros (threshold) the values below 2
b(3) = []; % suppress the 3rd entry of a vector
B = [b; b]; % create a matrix of size 2x4
c = B(:,2); % to access 2nd column - Advanced instructions
a = cos(b); a = sqrt(b); % usual function
help perform_wavelet_transform; % print the help
a = abs(b); a = real(b); a = imag(b); a = angle(b); % norm, real part and imaginary part of a complex
disp('Hello'); % display a text
disp( sprintf('Value of x=%.2f', x) ); % print a values with 2 digits
A(A==Inf) = 3; % replace Inf values by 3
A(:); % flatten a matrix into a column vector
max(A(:)); % max of a matrix
M = M .* (abs(M)>T); % threshold to 0 values below T. - Display
plot( 1:10, (1:10).^2 ); % display a 1D function
title('My title'); % title
xlabel('variable x'); ylabel('variable y'); % axis
subplot(2, 2, 1); % divide the screen in 2x2 and select 1st quadrant - Programmation
for i=1:4 % repeat the loop for i=1, i=2, i=3 et i=4
disp(i); % make here something
end
i = 4;
while i>0 % while syntax
disp(i); % do smth
i = i-1;
end
Load and visualize signals and images
- Load and plot a signal: (function load_signal.m should be in the toolbox of each course)
f = load_signal('Piece-Regular', n); % signal of size n
plot(f); - Load and display an image (download function load_image.m should be in the toolboxes)
I = load_image('lena');
imagesc(I); axis image; colormap gray(256);
