Anonymous functions in MATLAB - Mini Project: Build & Apply

Using Anonymous Functions in MATLAB

📖 Scenario: You are working on a simple calculator that can quickly compute squares of numbers. Instead of writing a full function file, you want to use a quick, small function that you can use immediately.

🎯 Goal: Create an anonymous function in MATLAB that calculates the square of a number, then use it to find the square of a given number.

📋 What You'll Learn

Create an anonymous function called square that takes one input and returns its square.

Use the square function to calculate the square of the number 7.

Display the result using disp.

💡 Why This Matters

🌍 Real World

Anonymous functions are useful for quick calculations or passing small functions as arguments without creating separate files.

💼 Career

Many engineering and data analysis jobs use MATLAB, and knowing anonymous functions helps write concise and efficient code.

1

Create an anonymous function

Create an anonymous function called square that takes one input x and returns x^2.

MATLAB

% Create an anonymous function called square
% Your code here

Hint

Use the syntax variable = @(input) expression; to create an anonymous function.

2

Assign the number to square

Create a variable called num and set it to 7.

MATLAB

square = @(x) x.^2;
% Create a variable num and set it to 7
% Your code here

Hint

Just assign the value 7 to the variable num.

3

Calculate the square using the anonymous function

Use the anonymous function square to calculate the square of num and store the result in a variable called result.

MATLAB

square = @(x) x.^2;
num = 7;
% Calculate the square of num using square function
% Your code here

Hint

Call the anonymous function like a normal function: result = square(num);.

4

Display the result

Use disp to display the value of result.

MATLAB

square = @(x) x.^2;
num = 7;
result = square(num);
% Display the result
% Your code here

Hint

Use disp(result); to show the output.

Practice

1. What is an anonymous function in MATLAB?

easy

A. A quick, unnamed function created using the '@' symbol.

B. A function saved in a separate file with a name.

C. A function that can only be used inside loops.

D. A function that requires no input arguments.

Solution

1. Step 1: Understand the definition of anonymous functions

   Anonymous functions in MATLAB are small, unnamed functions created using the '@' symbol.

2. Step 2: Compare options with the definition

   A quick, unnamed function created using the '@' symbol. correctly describes anonymous functions as quick, unnamed functions created with '@'. Other options describe named functions or incorrect properties.

3. Final Answer:

   A quick, unnamed function created using the '@' symbol. -> Option A

4. Quick Check:

   Anonymous function = unnamed function with '@' [OK]

Hint: Look for '@' symbol to identify anonymous functions [OK]

Common Mistakes:

• Confusing anonymous functions with regular named functions
• Thinking anonymous functions must have no inputs
• Assuming anonymous functions are saved in separate files

2. Which of the following is the correct syntax to create an anonymous function that squares its input x?

easy

A. f = @(x) x^2;

B. f = function(x) x^2;

C. f = @x x^2;

D. f = (x) => x^2;

Solution

1. Step 1: Recall MATLAB anonymous function syntax

   The correct syntax uses '@(args) expression;' so for squaring x, it is '@(x) x^2;'.

2. Step 2: Check each option

   f = @(x) x^2; matches the correct syntax. f = function(x) x^2; uses incorrect keyword 'function'. f = @x x^2; misses parentheses. f = (x) => x^2; uses arrow syntax from other languages.

3. Final Answer:

   f = @(x) x^2; -> Option A

4. Quick Check:

   Anonymous function syntax = @(args) expression [OK]

Hint: Remember '@(x) expression;' for anonymous functions [OK]

Common Mistakes:

• Omitting parentheses around input arguments
• Using 'function' keyword inside anonymous function
• Using arrow syntax from other languages

3. What is the output of the following MATLAB code?

f = @(x) x + 5;
result = f(10);
disp(result);

medium

A. 5

B. 10

C. 15

D. Error

Solution

1. Step 1: Understand the anonymous function definition

   The function f adds 5 to its input x.

2. Step 2: Calculate the function output for input 10

   f(10) = 10 + 5 = 15.

3. Final Answer:

   15 -> Option C

4. Quick Check:

   10 + 5 = 15 [OK]

Hint: Apply input to expression inside @(x) function [OK]

Common Mistakes:

• Confusing input and output values
• Expecting function to multiply instead of add
• Thinking anonymous functions cause errors without file

4. Identify the error in this MATLAB anonymous function:

g = @x x^2 + 3;

medium

A. Anonymous functions cannot use addition.

B. Missing parentheses around input argument x.

C. The '@' symbol is not allowed here.

D. The function must be saved in a separate file.

Solution

1. Step 1: Check anonymous function syntax

   Anonymous functions require parentheses around input arguments, like '@(x)'.

2. Step 2: Identify the syntax error

   The code uses '@x' without parentheses, which is invalid syntax.

3. Final Answer:

   Missing parentheses around input argument x. -> Option B

4. Quick Check:

   Anonymous function input must be in parentheses [OK]

Hint: Always use @(input) with parentheses [OK]

Common Mistakes:

• Omitting parentheses around inputs
• Thinking '@' can be used without parentheses
• Believing anonymous functions need separate files

5. You want to create an anonymous function h that takes two inputs x and y and returns x squared plus y cubed. Which is the correct way to write this?

hard

A. h = @(x y) x^2 + y^3;

B. h = @(x,y) x^2 * y^3;

C. h = @(x,y) (x^2), (y^3);

D. h = @(x,y) x^2 + y^3;

Solution

1. Step 1: Understand multiple inputs in anonymous functions

   Multiple inputs are separated by commas inside parentheses: @(x,y).

2. Step 2: Check the expression for correct operations

   The function should return x squared plus y cubed, so use '+' operator, not '*'.

3. Final Answer:

   h = @(x,y) x^2 + y^3; -> Option D

4. Quick Check:

   Multiple inputs use commas; '+' adds results [OK]

Hint: Separate inputs with commas and use correct operators [OK]

Common Mistakes:

• Omitting commas between inputs
• Using wrong operators like multiplication instead of addition
• Trying to separate expressions with commas outside parentheses