MAT file save and load in MATLAB - Step-by-Step Execution

Concept Flow - MAT file save and load

Create variables in workspace

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Use save('file.mat', 'var1', 'var2', ...)

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MAT file 'file.mat' created with variables

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Clear or close workspace

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Use load('file.mat')

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Variables restored in workspace

First, variables are saved into a MAT file. Later, loading the MAT file restores those variables back into the workspace.

Execution Sample

MATLAB

a = 10;
b = [1, 2, 3];
save('data.mat', 'a', 'b');
clear;
load('data.mat');

This code saves variables 'a' and 'b' into 'data.mat', clears the workspace, then loads them back.

Execution Table

Step	Action	Variables in Workspace	File Created/Loaded	Notes
1	Assign a=10	a=10	None	Variable 'a' created
2	Assign b=[1,2,3]	a=10, b=[1 2 3]	None	Variable 'b' created
3	save('data.mat', 'a', 'b')	a=10, b=[1 2 3]	'data.mat' created	Variables saved to file
4	clear	None	'data.mat' exists	Workspace cleared
5	load('data.mat')	a=10, b=[1 2 3]	'data.mat' loaded	Variables restored

💡 All variables saved and loaded successfully; workspace restored.

Variable Tracker

Variable	Start	After Save	After Clear	After Load
a	undefined	10	undefined	10
b	undefined	[1 2 3]	undefined	[1 2 3]

Key Moments - 2 Insights

Why do variables disappear after 'clear' but come back after 'load'?

The 'clear' command removes variables from the workspace (see step 4 in execution_table). The 'load' command reads the saved MAT file and restores those variables (step 5).

What happens if you save without specifying variable names?

If you use save('file.mat') without variable names, MATLAB saves all workspace variables at that moment.

Visual Quiz - 3 Questions

Look at the execution_table at step 3. What does the 'save' command do?

A Creates a MAT file with variables 'a' and 'b'

B Deletes variables 'a' and 'b'

C Loads variables from 'data.mat'

D Clears the workspace

💡 Hint

Check the 'File Created/Loaded' and 'Notes' columns at step 3 in execution_table.

At which step do variables 'a' and 'b' get removed from the workspace?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look at the 'Variables in Workspace' column in execution_table for step 4.

If you skip the 'clear' command, what will be the workspace state after loading 'data.mat'?

A Variables 'a' and 'b' will be duplicated

B Variables 'a' and 'b' will be overwritten with saved values

C Loading will fail because variables already exist

D Workspace will be empty

💡 Hint

Consider how 'load' works when variables already exist in the workspace.

Concept Snapshot

MAT file save and load in MATLAB:
- Use save('file.mat', 'var1', 'var2') to save variables.
- Use load('file.mat') to restore variables.
- 'clear' removes variables from workspace.
- Loading restores saved variables.
- Saving without variable names saves all workspace variables.

Full Transcript

This visual execution shows how MATLAB saves variables into a MAT file and loads them back. First, variables 'a' and 'b' are created. Then, the save command writes them into 'data.mat'. After clearing the workspace, the load command restores these variables. The variable tracker shows how 'a' and 'b' exist before saving, disappear after clearing, and come back after loading. Key moments clarify why variables vanish after clear and how save/load work. The quiz tests understanding of each step in the process.