Function handles in MATLAB - Mini Project: Build & Apply

Using Function Handles in MATLAB

📖 Scenario: You are working on a simple calculator program in MATLAB. You want to use function handles to store different operations like addition and multiplication, so you can call them easily later.

🎯 Goal: Build a MATLAB script that creates function handles for addition and multiplication, then uses them to calculate results.

📋 What You'll Learn

Create function handles for addition and multiplication

Use the function handles to calculate the sum and product of two numbers

Print the results

💡 Why This Matters

🌍 Real World

Function handles let you store and pass around operations easily, useful in calculators, data processing, and callbacks.

💼 Career

Understanding function handles is important for MATLAB programming jobs in engineering, data analysis, and scientific computing.

1

Create two variables with numbers

Create two variables called a and b with values 5 and 3 respectively.

MATLAB

% Create variables a and b with values 5 and 3
% Your code here

Hint

Use the assignment operator = to set the values.

2

Create function handles for addition and multiplication

Create a function handle called addFunc for addition and another called mulFunc for multiplication using anonymous functions.

MATLAB

a = 5;
b = 3;
% Create function handles addFunc and mulFunc
% Your code here

Hint

Use the syntax @(x,y) x + y for addition and similarly for multiplication.

3

Use the function handles to calculate results

Use the function handles addFunc and mulFunc to calculate the sum and product of a and b. Store the results in variables sumResult and productResult.

MATLAB

a = 5;
b = 3;
addFunc = @(x,y) x + y;
mulFunc = @(x,y) x * y;
% Calculate sumResult and productResult using function handles
% Your code here

Hint

Call the function handles like regular functions with (a,b).

4

Print the results

Print the values of sumResult and productResult using disp with descriptive text.

MATLAB

a = 5;
b = 3;
addFunc = @(x,y) x + y;
mulFunc = @(x,y) x * y;
sumResult = addFunc(a,b);
productResult = mulFunc(a,b);
% Print sumResult and productResult with descriptive text
% Your code here

Hint

Use disp(['Sum: ', num2str(sumResult)]) to print the sum.

Practice

1. What does a function handle in MATLAB allow you to do?

easy

A. Store a reference to a function that can be called later

B. Create a new variable type

C. Automatically run a function without calling it

D. Convert a function into a string

Solution

1. Step 1: Understand what a function handle is

   A function handle is a way to refer to a function without executing it immediately.

2. Step 2: Identify the purpose of function handles

   They let you store and pass functions as variables to call later.

3. Final Answer:

   Store a reference to a function that can be called later -> Option A

4. Quick Check:

   Function handle = reference to function [OK]

Hint: Think of function handles as pointers to functions [OK]

Common Mistakes:

• Confusing function handles with function execution
• Thinking function handles create new data types
• Assuming function handles convert functions to strings

2. Which of the following is the correct way to create a function handle for the built-in function sin in MATLAB?

easy

A. handle = sin();

B. handle = &sin;

C. handle = @sin;

D. handle = sin;

Solution

1. Step 1: Recall the syntax for creating function handles

   In MATLAB, function handles are created using the @ symbol followed by the function name without parentheses.

2. Step 2: Check each option

   handle = @sin; uses @sin which is correct. handle = sin(); calls sin immediately, C uses & which is not MATLAB syntax, and D assigns the function name as a variable without @ which is invalid.

3. Final Answer:

   handle = @sin; -> Option C

4. Quick Check:

   Use @ before function name to create handle [OK]

Hint: Use @ before function name, no parentheses [OK]

Common Mistakes:

• Adding parentheses when creating handles
• Using & instead of @
• Assigning function name without @

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

f = @(x) x^2 + 3;
result = f(2);

medium

A. 5

B. Error

C. 10

D. 7

Solution

1. Step 1: Understand the anonymous function definition

   The function f takes input x and returns x squared plus 3.

2. Step 2: Calculate the function output for x = 2

   f(2) = 2^2 + 3 = 4 + 3 = 7.

3. Final Answer:

   7 -> Option D

4. Quick Check:

   2 squared plus 3 equals 7 [OK]

Hint: Plug input into function formula carefully [OK]

Common Mistakes:

• Forgetting to square the input
• Adding instead of multiplying
• Expecting syntax error from anonymous function

4. Identify the error in the following MATLAB code that tries to create a function handle:

g = @(x) x + 1;
h = @g(2);

medium

A. Cannot use parentheses when creating a function handle

B. Function handle syntax is correct

C. Missing semicolon after function handle

D. Function handle must be created with a string

Solution

1. Step 1: Analyze the function handle creation

   The first line correctly creates an anonymous function g. The second line tries to create a handle h using @g(2), which is incorrect syntax.

2. Step 2: Understand correct function handle usage

   The @ operator must be followed by a function name or anonymous function without parentheses. Using parentheses calls the function, which is not allowed when creating a handle.

3. Final Answer:

   Cannot use parentheses when creating a function handle -> Option A

4. Quick Check:

   No parentheses allowed after @ when creating handles [OK]

Hint: No parentheses after @ when defining handles [OK]

Common Mistakes:

• Using parentheses after @
• Confusing function call with handle creation
• Thinking semicolon is required for correctness

5. You want to create a function handle that takes two inputs and returns their product plus 5. Which of the following anonymous function definitions is correct?

hard

A. f = @(x y) x * y + 5;

B. f = @(x, y) x * y + 5;

C. f = @(x, y) (x + y) * 5;

D. f = @(x, y) x * y + 5()

Solution

1. Step 1: Check the syntax for anonymous functions with multiple inputs

   Inputs must be separated by commas inside parentheses after @.

2. Step 2: Verify the expression matches the requirement

   f = @(x, y) x * y + 5; multiplies x and y, then adds 5, which matches the problem. f = @(x y) x * y + 5; misses the comma, C changes the operation, and D has invalid syntax with 5().

3. Final Answer:

   f = @(x, y) x * y + 5; -> Option B

4. Quick Check:

   Use commas between inputs and correct expression [OK]

Hint: Separate inputs with commas and write correct formula [OK]

Common Mistakes:

• Omitting commas between inputs
• Changing the math operation accidentally
• Adding parentheses after constants