Hello World in MATLAB

Every programming journey starts with Hello World. MATLAB makes this simple with its disp function.

The Code

Create a file named hello.m:

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disp('Hello, World!')

One line — just like Python, MATLAB keeps Hello World simple.

Understanding the Code

• disp() - A built-in function that displays text or variable values to the console
• 'Hello, World!' - A character array (string) enclosed in single quotes
• No semicolons needed for output - MATLAB uses semicolons to suppress output; omitting them prints the result
• No main function required - MATLAB scripts run top-to-bottom like a scripting language

Running with Docker (GNU Octave)

MATLAB is commercial software, so we use GNU Octave, a free and open-source alternative that is largely compatible with MATLAB syntax. The same .m files run in both environments.

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# Pull the GNU Octave image
docker pull gnuoctave/octave:9.4.0

# Run the program
docker run --rm -v $(pwd):/app -w /app gnuoctave/octave:9.4.0 octave --no-gui --no-window-system hello.m

Docker Command Flags

• --no-gui - Runs Octave in command-line mode (no graphical interface)
• --no-window-system - Prevents X11/display errors in headless environments like Docker

Running Locally

If you have MATLAB installed:

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# From MATLAB command window
>> hello

Or with GNU Octave:

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# Install Octave
# macOS
brew install octave

# Ubuntu/Debian
sudo apt install octave

# Run the script
octave --no-gui hello.m

Expected Output

Hello, World!

Alternatives to disp

MATLAB offers several ways to print output:

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% Using disp (simplest)
disp('Hello, World!')

% Using fprintf (C-style formatting)
fprintf('Hello, World!\n')

% Using disp with a variable
greeting = 'Hello, World!';
disp(greeting)

• disp() - Simple display, adds a newline automatically
• fprintf() - Formatted output (like C’s printf), requires explicit \n for newline
• Semicolons - Adding ; at the end of a line suppresses output in the console

Key Concepts

1. MATLAB is interpreted - Scripts run directly without a compilation step
2. Everything is a matrix - Even the string 'Hello, World!' is a 1x13 character array
3. 1-based indexing - Arrays start at index 1, not 0 (matching mathematical convention)
4. .m files - MATLAB scripts and functions are saved with the .m extension
5. Interactive workspace - Variables persist in the workspace between commands

MATLAB vs. GNU Octave

For this Hello World example, the code is identical in both MATLAB and GNU Octave. Octave was specifically designed to be compatible with MATLAB’s core language, so most basic scripts work without modification.

Key compatibility notes:

• Core syntax - Virtually identical for scripts and functions
• Built-in functions - Most common functions (disp, fprintf, plot, etc.) work the same way
• Differences emerge - In advanced toolbox features, Simulink, and some OOP syntax