Script files and editor in MATLAB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a script file that assigns 10 to variable x.

MATLAB

x = [1];

Drag options to blanks, or click blank then click option'

A'10'

B10

Cx

Dten

Attempts:

3 left

💡 Hint

Common Mistakes

Putting quotes around numbers, which makes them strings.

Using variable names instead of values.

The script assigns the number 10 to variable x. Numbers are written without quotes.

2fill in blank

medium

Complete the code to display the value of variable y in the script.

MATLAB

y = 5;
disp([1]);

Drag options to blanks, or click blank then click option'

A'y'

B5

Cdisp

Dy

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around the variable name in disp.

Passing a number directly instead of the variable.

The disp function shows the value of variable y. Use the variable name without quotes.

3fill in blank

hard

Fix the error in the script to correctly calculate the square of z.

MATLAB

z = 4;
square = z[1]2;

Drag options to blanks, or click blank then click option'

A^

B**

Cx

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using * instead of ^ for exponentiation.

Using ** which is invalid in MATLAB.

In MATLAB, the caret ^ is used for exponentiation to square a number.

4fill in blank

hard

Fill both blanks to create a script that calculates the area of a circle with radius r.

MATLAB

r = 3;
area = [1] * r[2] 2;

Drag options to blanks, or click blank then click option'

Api

B*

C^

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using * instead of ^ for squaring.

Using + instead of * for multiplication.

The area of a circle is pi * r^2. Use pi for π and ^ for power.

5fill in blank

hard

Fill all three blanks to create a script that calculates the average of three numbers a, b, and c.

MATLAB

a = 4;
b = 5;
c = 6;
avg = ([1] + [2] + [3]) / 3;

Drag options to blanks, or click blank then click option'

Aa

Bb

Cc

Davg

Attempts:

3 left

💡 Hint

Common Mistakes

Using the variable avg inside the sum.

Using numbers instead of variables inside the sum.

The average is the sum of a, b, and c divided by 3. Use the variable names inside the parentheses.

Practice

1. What is the main purpose of a script file in MATLAB?

easy

A. To create graphical user interfaces

B. To save and run a group of commands together

C. To store variables permanently

D. To compile MATLAB code into an executable

Solution

1. Step 1: Understand what script files do

   Script files contain a sequence of MATLAB commands saved in a file to run together.

2. Step 2: Compare options with script file purpose

   Only To save and run a group of commands together describes saving and running commands together, which is the main use of scripts.

3. Final Answer:

   To save and run a group of commands together -> Option B

4. Quick Check:

   Script files = save and run commands [OK]

Hint: Scripts group commands to run all at once [OK]

Common Mistakes:

• Confusing scripts with functions
• Thinking scripts store variables permanently
• Assuming scripts compile code

2. Which of the following is the correct way to save a script file in MATLAB Editor?

easy

A. Click File > Save or press Ctrl+S

B. Type save script in the command window

C. Right-click the command window and select Save

D. Use the command saveas('filename') in the script

Solution

1. Step 1: Identify how to save files in MATLAB Editor

   The Editor uses standard save options like File menu or Ctrl+S shortcut.

2. Step 2: Evaluate each option

   Only Click File > Save or press Ctrl+S correctly describes saving via Editor menu or shortcut. Others are incorrect or commands for different purposes.

3. Final Answer:

   Click File > Save or press Ctrl+S -> Option A

4. Quick Check:

   Save script = File menu or Ctrl+S [OK]

Hint: Use File menu or Ctrl+S to save scripts [OK]

Common Mistakes:

• Trying to save scripts from command window
• Using saveas command incorrectly
• Right-clicking command window instead of Editor

3. What will be the output when running this script in MATLAB Editor?

x = 5;
y = 3;
z = x + y;
disp(z);

medium

A. 8

B. 53

C. x + y

D. Error: Undefined variable

Solution

1. Step 1: Understand the script commands

   Variables x and y are assigned 5 and 3, then z is sum of x and y.

2. Step 2: Calculate the value of z and output

   z = 5 + 3 = 8, disp(z) prints 8 to the command window.

3. Final Answer:

   8 -> Option A

4. Quick Check:

   5 + 3 = 8 output [OK]

Hint: Add variables then display result [OK]

Common Mistakes:

• Concatenating numbers as strings
• Expecting variable names printed
• Assuming error without variable initialization

4. Identify the error in this MATLAB script:

for i = 1:3
  disp(i)
endd

medium

A. disp function used incorrectly

B. Missing semicolon after disp(i)

C. Loop variable i is not defined

D. Incorrect end keyword spelling

Solution

1. Step 1: Check the loop syntax

   The for loop uses 'endd' instead of 'end' to close the loop.

2. Step 2: Identify the syntax error

   MATLAB requires 'end' keyword exactly; 'endd' causes a syntax error.

3. Final Answer:

   Incorrect end keyword spelling -> Option D

4. Quick Check:

   Loop ends with 'end' keyword [OK]

Hint: Use exact 'end' to close loops [OK]

Common Mistakes:

• Typing 'endd' instead of 'end'
• Forgetting to close loops
• Adding unnecessary semicolons

5. You want to create a script that calculates the average of numbers stored in a vector data. Which script structure correctly computes and displays the average?

hard

A. avg = mean(data)
disp(total);

B. for i = 1:length(data)
avg = data(i) / length(data);
end
disp(avg);

C. total = sum(data);
count = length(data);
avg = total / count;
disp(avg);

D. avg = sum(data) * length(data);
disp(avg);

Solution

1. Step 1: Understand how to calculate average

   Average = sum of elements divided by number of elements.

2. Step 2: Check each script option

   total = sum(data);
   count = length(data);
   avg = total / count;
   disp(avg);

   correctly sums data, counts elements, divides, then displays average. Others have errors: A displays undefined total, C overwrites avg incorrectly in loop, D multiplies instead of dividing.

3. Final Answer:

   total = sum(data); count = length(data); avg = total / count; disp(avg); -> Option C

4. Quick Check:

   Average = sum / count [OK]

Hint: Average = sum divided by count, then display [OK]

Common Mistakes:

• Using mean without displaying correct variable
• Calculating average inside loop incorrectly
• Multiplying sum by length instead of dividing