Input and output arguments in MATLAB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a function with multiple outputs

What is the output of the following MATLAB code?

MATLAB

function [a, b] = example(x)
    a = x + 1;
    b = x * 2;
end

[a_out, b_out] = example(3);
disp([a_out, b_out]);

A [3 6]

B [4 6]

C [4 3]

D [6 4]

💡 Hint

Remember the function returns two outputs: a = x+1 and b = x*2.

The function example adds 1 to input x for output a, and multiplies x by 2 for output b. For x=3, a=4 and b=6, so the output is [4 6].

❓ Predict Output

intermediate

Value of output argument after function call

What is the value of variable y after running this code?

MATLAB

function y = squarePlusOne(x)
    y = x^2 + 1;
end

result = squarePlusOne(4);
y = result;

A 5

B 16

C 17

D 8

💡 Hint

Calculate 4 squared plus 1.

4 squared is 16, plus 1 equals 17, so y is 17.

🔧 Debug

advanced

Identify the error in function output assignment

What error will this MATLAB code produce when run?

MATLAB

function [a, b] = faultyFunc(x)
    a = x + 2;
end

[a_out, b_out] = faultyFunc(5);

A Error: Variable 'b' is undefined.

B Error: Function syntax error.

C No error, outputs are [7, 0].

D Error: Not enough output arguments.

💡 Hint

Check if the function returns all requested outputs.

The function defines two outputs but only assigns one. Calling with two outputs causes 'Not enough output arguments' error.

📝 Syntax

advanced

Correct syntax for multiple output arguments

Which option shows the correct syntax to define a function with two output arguments in MATLAB?

A function [out1, out2] = myFunc(input)

B function (out1, out2) = myFunc(input)

C function out1 out2 = myFunc(input)

D function out1, out2 = myFunc(input)

💡 Hint

Look for square brackets around output variables.

MATLAB requires square brackets around multiple outputs in function definition: function [out1, out2] = myFunc(input)

🚀 Application

expert

Number of output arguments returned by a function call

Given the function below, how many output arguments does the call [x, y] = computeValues(2) return?

MATLAB

function [a, b, c] = computeValues(n)
    a = n;
    b = n^2;
    c = n^3;
end

[x, y] = computeValues(2);

A 2

B 3

C 1

D 0

💡 Hint

The number of outputs depends on the left side of the call.

Even though the function returns 3 outputs, the call requests only 2 outputs, so only 2 are returned.

Practice

1. What is the main purpose of input arguments in a MATLAB function?

easy

A. To send data into the function for processing

B. To display results on the screen

C. To store variables permanently

D. To create new functions inside the main function

Solution

1. Step 1: Understand input arguments

   Input arguments are values or data you give to a function so it can use them inside.

2. Step 2: Identify the purpose

   The main purpose is to send data into the function for it to work on.

3. Final Answer:

   To send data into the function for processing -> Option A

4. Quick Check:

   Input arguments = send data in [OK]

Hint: Input arguments bring data into functions [OK]

Common Mistakes:

• Confusing input arguments with output arguments
• Thinking input arguments display results
• Assuming input arguments create new functions

2. Which of the following is the correct syntax to define a MATLAB function with one input and one output argument?

easy

A. function output = myFunc(input)

B. function myFunc(input) = output

C. function (output) = myFunc input

D. function myFunc output(input)

Solution

1. Step 1: Recall MATLAB function syntax

   The correct syntax starts with 'function', then output, '=', function name, and input in parentheses.

2. Step 2: Match the syntax

   function output = myFunc(input) matches this pattern exactly: function output = myFunc(input)

3. Final Answer:

   function output = myFunc(input) -> Option A

4. Quick Check:

   Syntax = function output = name(input) [OK]

Hint: Output = functionName(input) is the right order [OK]

Common Mistakes:

• Placing output after function name without '='
• Missing parentheses around input
• Using '=' incorrectly in function header

3. What will be the output of the following MATLAB function call?

function y = squarePlusOne(x)
    y = x^2 + 1;
end

result = squarePlusOne(3);

medium

A. 9

B. 10

C. 7

D. 16

Solution

1. Step 1: Calculate the square of input

   Input x is 3, so x^2 = 3^2 = 9.

2. Step 2: Add 1 to the squared value

   9 + 1 = 10.

3. Final Answer:

   10 -> Option B

4. Quick Check:

   3 squared plus 1 = 10 [OK]

Hint: Square input, then add one [OK]

Common Mistakes:

• Forgetting to add 1 after squaring
• Using multiplication instead of power
• Confusing output with input

4. Identify the error in this MATLAB function definition:

function output = addNumbers(a, b)
    output = a + b
end

medium

A. Input arguments must be in square brackets

B. Function name should be capitalized

C. Output variable cannot be named 'output'

D. Missing semicolon after output assignment

Solution

1. Step 1: Check MATLAB syntax rules

   Each statement should end with a semicolon to suppress output in functions.

2. Step 2: Identify missing semicolon

   The line 'output = a + b' lacks a semicolon at the end.

3. Final Answer:

   Missing semicolon after output assignment -> Option D

4. Quick Check:

   Statements need semicolons [OK]

Hint: End statements with semicolon inside functions [OK]

Common Mistakes:

• Ignoring semicolon causes unwanted output
• Thinking function names must be capitalized
• Using wrong brackets for inputs

5. You want to write a MATLAB function that takes two numbers as input and returns both their sum and product as outputs. Which function header is correct?

hard

A. function sum, product = calculate(a, b)

B. function calculate(a, b) = [sum, product]

C. function [sum, product] = calculate(a, b)

D. function calculate = [sum, product](a, b)

Solution

1. Step 1: Recall syntax for multiple outputs

   Multiple outputs are enclosed in square brackets before the '=' sign.

2. Step 2: Match correct syntax

   function [sum, product] = calculate(a, b) uses square brackets for outputs and correct order: function [sum, product] = calculate(a, b)

3. Final Answer:

   function [sum, product] = calculate(a, b) -> Option C

4. Quick Check:

   Multiple outputs use square brackets [OK]

Hint: Use square brackets for multiple outputs [OK]

Common Mistakes:

• Omitting square brackets for multiple outputs
• Placing outputs after function name without brackets
• Using '=' incorrectly in function header