Input and output arguments in MATLAB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are input arguments in a MATLAB function?

Input arguments are values or variables passed into a function when it is called. They provide the function with data to work on.

beginner

What are output arguments in a MATLAB function?

Output arguments are values that a function returns after execution. They allow the function to send results back to the caller.

beginner

How do you define a function with one input and one output argument in MATLAB?

Use the syntax:
function output = functionName(input)
where input is the input argument and output is the output argument.

intermediate

Can a MATLAB function have multiple output arguments? How?

Yes. Use square brackets to list multiple outputs:
function [out1, out2] = functionName(in1, in2)
This returns two outputs from the function.

intermediate

What happens if you call a MATLAB function without specifying output arguments?

If no output is specified, MATLAB will not store the returned values. The function still runs, but outputs are discarded unless the function displays them.

How do you declare a MATLAB function that takes two inputs and returns one output?

A function (input1, input2) = output func

B function output = func(input1, input2)

C function func = output(input1, input2)

D function [input1, input2] = func(output)

The correct syntax is: function output = func(input1, input2). Inputs go in parentheses, output before the equals sign.

What symbol is used to enclose multiple output arguments in a MATLAB function definition?

A Square brackets [ ]

B Curly braces { }

C Parentheses ( )

D Angle brackets < >

Square brackets [ ] are used to list multiple output arguments in MATLAB function definitions.

If a MATLAB function has outputs but you call it without assigning outputs, what happens?

A MATLAB throws an error

B Outputs are returned and stored automatically

C Outputs are discarded unless displayed inside the function

D Function does not run

If outputs are not assigned, MATLAB runs the function but discards outputs unless the function prints them.

Which of these is a valid way to call a function with two outputs in MATLAB?

A a, b = myFunc(x, y)

B myFunc(x, y) -> a, b

C myFunc[a, b](x, y)

D [a, b] = myFunc(x, y)

The correct way is to use square brackets on the left: [a, b] = myFunc(x, y).

What keyword starts a function definition in MATLAB?

A function

B def

C func

D begin

MATLAB functions start with the keyword 'function'.

Explain how input and output arguments work in MATLAB functions.

Think about how you give information to a function and how it sends back results.

Describe what happens if you call a MATLAB function with outputs but do not capture those outputs.

Consider what happens if you ignore the results a function gives you.

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