First MATLAB program - Step-by-Step Execution

Concept Flow - First MATLAB program

Start MATLAB

↓

Write code: disp('Hello, world!')

↓

Run code

↓

MATLAB prints message

↓

End

This flow shows writing a simple MATLAB program that prints a message and running it to see the output.

Execution Sample

MATLAB

disp('Hello, world!')

This code prints the text Hello, world! to the MATLAB command window.

Execution Table

Step	Action	Code Evaluated	Output
1	Start MATLAB environment
2	Write code to display message	disp('Hello, world!')
3	Run the code	disp('Hello, world!')	Hello, world!
4	Program ends

💡 Program ends after displaying the message.

Variable Tracker

Variable	Start	After disp	Final
No variables used	-	-	-

Key Moments - 2 Insights

Why does the program only show the message and not store it?

Because disp() only prints the message to the screen and does not save it in any variable, as shown in execution_table step 3.

What happens if you forget the single quotes around the message?

MATLAB will give an error because disp() expects a string input enclosed in single quotes, as seen in execution_table step 2 where the code is disp('Hello, world!').

Visual Quiz - 3 Questions

Look at the execution table, what is printed at step 3?

A Hello, world!

B disp('Hello, world!')

C No output

D Error message

💡 Hint

Check the Output column in execution_table row 3.

At which step does MATLAB run the code?

A Step 2

B Step 3

C Step 1

D Step 4

💡 Hint

Look at the Action column in execution_table where it says 'Run the code'.

If you remove the single quotes around the message, what will happen?

A The message prints correctly

B The program runs but prints nothing

C MATLAB shows an error

D The program stores the message in a variable

💡 Hint

Refer to key_moments about missing quotes causing errors.

Concept Snapshot

disp('message') prints text to the MATLAB command window.
Always enclose text in single quotes.
No variables needed to display simple messages.
Run code by pressing Run or typing the command.
Output appears immediately in the command window.

Full Transcript

This visual execution shows the first MATLAB program that prints Hello, world! to the screen. The flow starts with opening MATLAB, writing the code disp('Hello, world!'), running it, and seeing the output. The execution table traces each step: starting MATLAB, writing code, running code, and program end. The variable tracker shows no variables are used. Key moments clarify that disp only prints and requires quotes around text. The quiz tests understanding of output, running step, and syntax errors. The snapshot summarizes how to print messages in MATLAB simply.

Practice

1. What does the MATLAB command disp('Hello, world!') do?

easy

A. It saves the text Hello, world! to a file.

B. It displays the text Hello, world! on the screen.

C. It creates a variable named Hello, world!.

D. It runs a loop that prints Hello, world! multiple times.

Solution

1. Step 1: Understand the disp function

   The disp function in MATLAB shows text or values on the screen.

2. Step 2: Analyze the input to disp

   The input is a string 'Hello, world!' which means it will print this exact text.

3. Final Answer:

   It displays the text Hello, world! on the screen. -> Option B

4. Quick Check:

   disp('text') shows text [OK]

Hint: disp shows text inside single quotes [OK]

Common Mistakes:

• Thinking disp saves text to a file
• Using double quotes instead of single quotes
• Confusing disp with variable creation

2. Which of the following is the correct syntax to display the message Hello in MATLAB?

easy

A. disp('Hello')

B. display(Hello)

C. disp(Hello)

D. print('Hello')

Solution

1. Step 1: Check the correct function name

   MATLAB uses disp to display messages, not display or print.

2. Step 2: Check the string syntax

   Strings must be inside single quotes in MATLAB, so disp('Hello') is correct.

3. Final Answer:

   disp('Hello') -> Option A

4. Quick Check:

   disp with single quotes is correct [OK]

Hint: Use disp with single quotes for text [OK]

Common Mistakes:

• Using double quotes instead of single quotes
• Using wrong function names like print or display
• Missing quotes around text

3. What will be the output of this MATLAB code?

disp('Welcome to MATLAB!')

medium

A. Welcome to MATLAB!

B. disp('Welcome to MATLAB!')

C. SyntaxError

D. No output

Solution

1. Step 1: Understand disp function behavior

   The disp function prints the string inside the parentheses to the screen.

2. Step 2: Check the string format

   The string is correctly enclosed in single quotes, so it will print exactly as given.

3. Final Answer:

   Welcome to MATLAB! -> Option A

4. Quick Check:

   disp prints string text [OK]

Hint: disp prints text inside single quotes exactly [OK]

Common Mistakes:

• Expecting disp to print the command itself
• Using double quotes causing errors
• Forgetting to use disp function

4. Identify the error in this MATLAB code:

disp(Welcome to MATLAB!)

medium

A. Parentheses are not allowed with disp

B. Missing semicolon at the end

C. disp function does not exist

D. Text is not inside single quotes

Solution

1. Step 1: Check the input to disp

   The text Welcome to MATLAB! is not inside single quotes, so MATLAB treats it as variables or commands.

2. Step 2: Understand string syntax in MATLAB

   Strings must be enclosed in single quotes to be recognized as text.

3. Final Answer:

   Text is not inside single quotes -> Option D

4. Quick Check:

   Strings need single quotes [OK]

Hint: Always put text inside single quotes in disp [OK]

Common Mistakes:

• Omitting quotes around text
• Thinking semicolon is required for disp
• Believing disp is not a function

5. You want to write a MATLAB program that displays two lines:
Hello
and
Welcome to MATLAB
Which code will do this correctly?

hard

A. disp('Hello\nWelcome to MATLAB')

B. disp('Hello')
disp(Welcome to MATLAB)

C. disp('Hello')
disp('Welcome to MATLAB')

D. disp('Hello' + 'Welcome to MATLAB')

Solution

1. Step 1: Check how to display multiple lines

   Using two separate disp calls prints each line separately.

2. Step 2: Analyze each option

   disp('Hello') disp('Welcome to MATLAB') uses two disp calls with correct strings. disp('Hello\nWelcome to MATLAB') tries to use \n inside single quotes which MATLAB does not interpret as newline. disp('Hello') disp(Welcome to MATLAB) misses quotes in second disp. disp('Hello' + 'Welcome to MATLAB') tries to add strings which is invalid in MATLAB.

3. Final Answer:

   disp('Hello') disp('Welcome to MATLAB') -> Option C

4. Quick Check:

   Use separate disp calls for multiple lines [OK]

Hint: Use separate disp lines for multiple messages [OK]

Common Mistakes:

• Using \n inside single quotes expecting newline
• Missing quotes around text
• Trying to add strings with + operator