How to Add Function to MATLAB?

Adding a function to MATLAB involves creating a code block that performs a specific task, which you can then reuse. One common way to add a function is by defining it as a local function within a script or live script file.

To add a function in MATLAB, you can either create a standalone function file or define a function directly within a script or live script as a local function. This guide focuses on adding local functions, a method useful for specific tasks within a larger script workflow.

Creating Local Functions in Scripts or Live Scripts

Local functions are defined within a script or live script file and are only accessible from within that same file. This is a convenient way to modularize code used repeatedly within a single script.

Here’s how to add a local function based on the referenced method:

1. Create a New Script or Live Script: go to the Home tab and select New Script or New Live Script. This opens a new editor window where you can write your code.

2. Add Code: Then, add code to the file. You can include regular script commands and variable definitions before or after your function definition (though typically local functions are placed at the end of the file).

3. Define the Local Function: Define your function using the function keyword. Each local function must begin with its own function definition statement and end with the end keyword. The function definition includes the output arguments (if any), the function name, and the input arguments (if any) in parentheses.

   % Your main script code can go here
   
   % Call the local function
   result = myLocalFunction(5, 3);
   disp(['Result from local function: ', num2str(result)]);
   
   % Define the local function at the end of the file
   function output = myLocalFunction(input1, input2)
       % This is the function body
       output = input1 + input2;
   end % End of the local function definition

In this example:

• myLocalFunction is the name of the local function.
• input1 and input2 are the input arguments.
• output is the output argument.
• The code between function and end is the function body, where the computation happens.

Key characteristics of local functions:

• They must be defined within the same file as the script or other functions that call them.
• They are typically placed after the main script code.
• They enhance code organization and reusability within a single file.

Creating Standalone Functions

The most common way to create a reusable function in MATLAB is to save it as a standalone function file (.m file).

• Create a new .m file.
• The very first line (excluding comments) must be the function definition line (function [outputs] = functionName(inputs)).
• Save the file with the same name as the function (e.g., myFunction.m).
• These functions can be called from any script, function, or the Command Window, provided they are in MATLAB's search path or the current folder.

Feature	Local Function in Script/Live Script	Standalone Function (.m file)
Definition	Within a script or live script file	In its own dedicated .m file
Accessibility	Only within the file where it is defined	Accessible from anywhere in MATLAB's path
Naming	Name can be different from the file name (though often not)	File name must match the function name (first function)
Primary Use	Tasks specific to a particular script; modularity within a file	Reusable code blocks for general purposes; libraries

Why Use Functions?

Incorporating functions into your MATLAB code offers several advantages:

• Reusability: Avoid writing the same code multiple times.
• Organization: Break down complex programs into smaller, manageable parts.
• Readability: Make your code easier to understand and maintain.
• Testing: Test individual components of your program in isolation.

By following these methods, particularly the steps for creating local functions in scripts or live scripts, you can effectively add and utilize functions in your MATLAB projects.