備註：%%之間的是註釋%%
%註釋其後面的內容
代碼可以複製%之間的內容（包括%）%到MATLAB裏執行
一、matlab基本命令的使用
%% I. 清空環境變量及命令
clear all % 清除Workspace中的所有變量clc % 清除Command Window中的所有命令
%% II. 變量命令規則
%%
% 1. 變量名區分大小寫
A = 2
a = 3
%%
二、變量命名規則
% 2. 變量名長度不超過63位
% ABCDEFGHIJKLMNOPQRSTUVWXYZ123456ABCDEFGHIJKLMNOPQRSTUVWXYZ123456 = 3%%
% 3. 變量名以字母開頭，可以由字母、數字和下劃線組成，但不能使用標點
% 3A = 4
% .a = 5
% /b = 5
a_2 = 3
% a.2 = 4
%%
% 4. 變量名應簡潔明瞭，通過變量名可以直觀看出變量所表示的物理意義
A = rand(3,5)
rows = size(A, 1)
cols = size(A, 2)
三、matlab基本數據類型
%% III. MATLAB數據類型
%%% 1. 數字
2 + 4
10 - 7
3 * 5
8 / 2
%%
% 2. 字符與字符串
s = 'a'
abs(s)
char(65)
num2str(65)
str = 'I Love MATLAB & Machine Learning.'
length(str)
doc num2str
%%
% 3. 矩陣
A = [1 2 3; 4 5 2; 3 2 7]
B = A'
C = A(:)
D = inv(A)
A * D
E = zeros(10,5,3)
E(:,:,1) = rand(10,5)
E(:,:,2) = randi(5, 10,5)
E(:,:,3) = randn(10,5)
%%
% 4. 元胞數組
A = cell(1, 6)
A{2} = eye(3)
A{5} = magic(5)
B = A{5}
%%
% 5. 結構體
books = struct('name',{{'Machine Learning','Data Mining'}},'price',[30 40])
books.name
books.name(1)
books.name{1}
%% IV. MATLAB矩陣操作
%%
% 1. 矩陣的定義與構造
A = [1 2 3 5 8 5 4 6]
B = 1:2:9
C = repmat(B, 3, 1)
D = ones(2, 4)
%%
% 2. 矩陣的四則運算
A = [1 2 3 4; 5 6 7 8]
B = [1 1 2 2; 2 2 1 1]
C = A + B
D = A - B
E = A * B'
F = A .* B
G = A / B % G * B = A G * B * pinv(B) = A * pinv(B) G = A * pinv(B)
H = A ./ B
%%
% 3. 矩陣的下標
A = magic(5)
B = A(2,3)
C = A(3,:)
D = A(:,4)
[m, n] = find(A > 20)
四、MATLAB邏輯與流程控制
%% V. MATLAB邏輯與流程控制
%%% 1. if ... else ... end
A = rand(1,10)
limit = 0.75;
B = (A > limit); % B is a vector of logical values
if any(B)
fprintf('Indices of values > %4.2f: \n', limit);
disp(find(B))
else
disp('All values are below the limit.')
end
%%
% 2. for ... end
k = 10;
hilbert = zeros(k,k); % Preallocate matrix
for m = 1:k
for n = 1:k
hilbert(m,n) = 1/(m+n -1);
end
end
hilbert
%%
% 3. while ... end
n = 1;
nFactorial = 1;
while nFactorial < 1e100
n = n + 1;
nFactorial = nFactorial * n;
end
n
factorial(69)
factorial(70)
prod(1:69)
prod(1:70)
%%
% 4. switch ... case ... end
mynumber = input('Enter a number:');
switch mynumber
case -1
disp('negative one');
case 0
disp('zero');
case 1
disp('positive one');
otherwise
disp('other value');
end
五、MATLAB腳本與函數文件
%% VI. MATLAB腳本與函數文件
%%% 1. 腳本文件
myScript
%%
% 2. 函數文件
mynumber = input('Enter a number:');
output = myFunction(mynumber)
六、MATLAB基本繪圖操作
%% VII. MATLAB基本繪圖操作
%%% 1. 二維平面繪圖
x = 0:0.01:2*pi;
y = sin(x);
figure
plot(x, y)
title('y = sin(x)')
xlabel('x')
ylabel('sin(x)')
xlim([0 2*pi])
x = 0:0.01:20;
y1 = 200*exp(-0.05*x).*sin(x);
y2 = 0.8*exp(-0.5*x).*sin(10*x);
figure
[AX,H1,H2] = plotyy(x,y1,x,y2,'plot');
set(get(AX(1),'Ylabel'),'String','Slow Decay')
set(get(AX(2),'Ylabel'),'String','Fast Decay')
xlabel('Time (\musec)')
title('Multiple Decay Rates')
set(H1,'LineStyle','--')
set(H2,'LineStyle',':')
%%
% 2. 三維立體繪圖
t = 0:pi/50:10*pi;
plot3(sin(t),cos(t),t)
xlabel('sin(t)')
ylabel('cos(t)')
zlabel('t')
grid on
axis square
%%
% 3. 圖形的保存與導出
% (1) Edit → Copy Figure
% (2) Toolbar → Save
% (3) print('-depsc','-tiff','-r300','picture1')
% (4) File → Export Setup
%% VIII. MATLAB文件導入
%%
% 1. mat格式
save data.mat x y1 y2
clear all
load data.mat
%%
% 2. txt格式
M = importdata('myfile.txt');
S = M.data;
save 'data.txt' S -ascii
T = load('data.txt');
isequal(S, T)
%%
% 3. xls格式
xlswrite('data.xls',S)
W = xlsread('data.xls');
isequal(S, W)
xlswrite('data.xlsx',S)
U = xlsread('data.xlsx');
isequal(S, U)
%%
% 4. csv格式
csvwrite('data.csv',S)
V = csvread('data.csv');
isequal(S, V)