MATLAB Basics and Environment — Study Notes Summary & Study Notes

🖥️ Overview of the MATLAB Environment

MATLAB (Matrix Laboratory) is an interactive environment for numerical computation, visualization, and programming. The interface is organized around a few core panels that you will use frequently: Command Window, Workspace, Editor, and Current Directory. Understanding how these pieces fit together helps you develop, run, and manage code efficiently.

🧩 Command Window

The Command Window is where you enter commands and see immediate results. Use it for quick calculations, testing expressions, and running small scripts.

• Enter a command and press Enter to execute. Example: $x = 3$ or $A = [1 2; 3 4]$.
• Use the up/down arrow keys to browse command history.
• End a line with a semicolon ; to suppress output; omit it to display results.

📦 Workspace

The Workspace shows all current variables and their sizes/types. It’s a snapshot of the current session state.

• You can inspect variable values, sizes, and classes at a glance.
• Clear variables with clear or clear varName to free memory.
• Save or load variables using save and load (see file management section).

✍️ Editor

The Editor (also called MATLAB Editor or Live Editor for rich documents) is where you write, edit, and debug code.

• Create script files (.m) to run sequences of commands.
• Create function files (.m) when you need reusable code with input/output arguments.
• Use breakpoints and the debugger to step through code and inspect variables.

📁 Current Directory & Path

The Current Directory determines where MATLAB looks for files by default and where it saves output when no path is specified.

• Change directory with cd folderName or use the Current Folder browser.
• MATLAB searches folders on its path to find functions and scripts. Add folders using addpath or the Set Path GUI.

🔢 Entering Matrices and Vectors

MATLAB treats most data as arrays (vectors, matrices, multidimensional arrays).

• Row vector: $v = [1 2 3]$
• Column vector: $c = [1; 2; 3]$
• Matrix: $A = [1 2; 3 4]$
• Indexing: access elements with parentheses: $A(2,1)$ is row 2, column 1.
• Colon operator: $1:5$ produces $[1 2 3 4 5]$; use $A(:,2)$ to select the entire 2nd column.
• Transpose: $A'$ gives the transpose (for numeric arrays).

🔤 Creating Variables & Workspace Management

Create variables simply by assigning values: x = 10; or name = 'Alice';.

• Variable names are case-sensitive and must start with a letter, followed by letters, digits, or underscores.
• Inspect variable contents using whos for detailed list, who for names only.
• Remove variables with clear varName or clear to remove all variables.
• Use save filename to save workspace variables to a .mat file and load filename to restore them.

🧮 Basic Arithmetic & Using MATLAB as a Calculator

MATLAB evaluates arithmetic expressions following standard precedence.

• Basic operators: +, -, * (matrix multiply), / (matrix right divide), ^ (power).
• Elementwise operations use a dot: .*, ./, .^ for element-by-element multiply/divide/power.
• Examples: y = 2 + 3*4;, B = A .* 2;
• Use the colon : and functions like sum, mean, and max for vectorized operations.

📚 Built-in Functions & Constants

MATLAB provides many built-in functions and constants for math, statistics, and engineering.

• Common functions: sin, cos, tan, exp, log, sqrt used like sin(pi/2) or sqrt(4).
• Constants: pi is available as pi.
• Use help functionName or doc functionName to read usage and examples (e.g., help sin).
• Many specialized toolboxes extend available functions for signal processing, optimization, etc.

💾 Managing Files and Directories (save, load, cd, path)

File and directory management keeps projects organized and reproducible.

• cd folderPath changes the Current Directory.
• pwd shows the present working directory.
• save filename writes variables to filename.mat; save filename var1 var2 saves specific variables.
• load filename loads variables from a .mat file into the Workspace.
• addpath folderPath and rmpath folderPath adjust the function search path. Use savepath to persist changes.

📜 Script Files vs. Function Files

Understand when to use scripts and when to write functions.

• Script files (.m) contain a sequence of MATLAB commands and operate on the base workspace. Use scripts for simple workflows and quick experiments.
• Function files define a function with inputs and outputs using the function keyword. Functions have their own local workspace and are reusable and safer for modular code.
  • Example function header: function out = myFunc(in1, in2)
• Prefer functions for modularity, testing, and reuse; use scripts for orchestration and interactive work.

✅ Quick Tips & Common Commands

• help <name> and doc <name> — documentation.
• clc — clear Command Window.
• clear / clearvars — clear variables.
• who / whos — list variables.
• edit filename — open or create an m-file in the Editor.
• Use vectorized operations instead of loops where possible for speed.

These notes cover the essentials to get started with MATLAB: navigating the interface, creating and managing variables, performing arithmetic and matrix operations, using built-in functions, handling files, and understanding the distinction between scripts and functions. Practice by creating small scripts and functions, exploring the Workspace, and consulting help/doc as needed.