【Fundamentals】Detailed Explanation of Basic Structure and Usage of MATLAB Functions

# 1. Introduction to MATLAB Functions**

MATLAB functions are reusable code blocks that encapsulate code snippets to perform specific tasks. They enhance code organization, maintainability, and reusability. MATLAB functions are divided into built-in functions (provided by MATLAB) and user-defined functions (created by users).

# 2. Creating and Calling MATLAB Functions

### 2.1 Syntax and Structure of Function Definitions

MATLAB function definitions follow this syntax:

function [output_args] = function_name(input_args)
     % Function body
end

Where:

- `function_name`: The name of the function, which must start with a letter and cannot contain spaces or special characters.
- `input_args`: The input arguments to the function, which can be multiple and are separated by commas.
- `output_args`: The output arguments from the function, which can be multiple and are enclosed in square brackets.
- `% Function body`: The main body of the function containing the code to be executed.

### 2.2 Passing and Using Function Parameters

Function parameters can be passed by value or by reference.

**Pass by Value**: The value of the input argument is copied into the function, and any modifications to the parameter within the function do not affect the original variable.

**Pass by Reference**: The memory address of the input argument is passed into the function, and any modifications to the parameter within the function will affect the original variable.

To use pass by reference, an `&` symbol must be added before the parameter.

### 2.3 Obtaining and Handling Function Return Values

Functions can return one or more values using the `return` statement. If a function does not explicitly return any value, it defaults to `[]`.

To obtain a function's return value, use the syntax `[output_args] = function_name(input_args)`.

**Example:**

% Define a function to calculate the sum of two numbers
function sum = add_numbers(a, b)
     sum = a + b;
end

% Call the function and obtain the return value
result = add_numbers(5, 10);
disp(result);   % Outputs: 15

# 3. Types and Applications of MATLAB Functions

### 3.1 Built-in Functions and User-defined Functions

MATLAB offers a rich set of built-in functions that cover a variety of mathematical, statistical, graphical, and data processing operations. These functions are optimized for performance and can meet the needs of most common tasks.

User-defined functions are created by users to solve specific problems or encapsulate repetitive tasks. Custom functions can be tailored as needed, providing greater flexibility.

### 3.2 Single-file Functions and Multi-file Functions

Single-file functions contain both the function definition and the code in one file, making the structure simple and easy to maintain.

Multi-file functions split the function definition and code across different files, typically including one main function file and multiple helper function files. This structure is better suited for larger and more complex functions, facilitating code organizati