Why functions organize MATLAB code - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a simple function that adds two numbers.

MATLAB

function result = addNumbers(a, b)
    result = a [1] b;
end

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

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction or multiplication instead of addition.

Forgetting to use an operator.

The plus sign + adds two numbers in MATLAB.

2fill in blank

medium

Complete the code to call the function 'addNumbers' with inputs 3 and 5.

MATLAB

sum = [1](3, 5);

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

AsumNumbers

BaddNumbers

Cadd

DsumAdd

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong or misspelled function name.

Confusing function name with variable names.

The function is named addNumbers, so calling it requires that exact name.

3fill in blank

hard

Fix the error in the function definition by completing the missing keyword.

MATLAB

[1] addNumbers(a, b)
    result = a + b;
end

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

Afunction

Bdef

Cfunc

Dfun

Attempts:

3 left

💡 Hint

Common Mistakes

Using Python or other language keywords like def.

Omitting the keyword entirely.

In MATLAB, functions start with the keyword function.

4fill in blank

hard

Fill both blanks to create a function that returns the square of a number.

MATLAB

function [1] = squareNumber([2])
    [1] = [2]^2;
end

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

Aresult

Bnum

Cvalue

Doutput

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same name for input and output variables.

Forgetting to use the power operator ^.

The function output variable is result and the input variable is num.

5fill in blank

hard

Fill all three blanks to create a function that checks if a number is positive.

MATLAB

function [1] = isPositive([2])
    if [2] [3] 0
        [1] = true;
    else
        [1] = false;
    end
end

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

Aresult

Bnum

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong comparison operator.

Mixing up input and output variable names.

The function returns result, takes input num, and checks if num > 0.

Practice

1. Why do we use functions to organize MATLAB code?

easy

A. To group related commands and make code reusable

B. To make the code run faster

C. To avoid using variables

D. To write code without any comments

Solution

1. Step 1: Understand the purpose of functions

   Functions group related commands so the code is organized and easier to manage.

2. Step 2: Recognize benefits of functions

   Functions make code reusable and easier to read, not necessarily faster or comment-free.

3. Final Answer:

   To group related commands and make code reusable -> Option A

4. Quick Check:

   Functions organize code = To group related commands and make code reusable [OK]

Hint: Functions group related commands for reuse [OK]

Common Mistakes:

• Thinking functions always speed up code
• Believing functions remove the need for variables
• Assuming functions replace comments

2. Which of the following is the correct way to start a function in MATLAB?

easy

A. def myFunc(input):

B. function output = myFunc(input)

C. func myFunc(input) {

D. function: myFunc(input)

Solution

1. Step 1: Recall MATLAB function syntax

   MATLAB functions start with the keyword 'function' followed by output, equals sign, and function name with inputs in parentheses.

2. Step 2: Compare options

   Only function output = myFunc(input) matches MATLAB syntax; others are from different languages or incorrect.

3. Final Answer:

   function output = myFunc(input) -> Option B

4. Quick Check:

   MATLAB function syntax = function output = myFunc(input) [OK]

Hint: MATLAB functions start with 'function' keyword [OK]

Common Mistakes:

• Using Python or C syntax instead of MATLAB
• Missing the 'function' keyword
• Incorrect punctuation or braces

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

function y = squareNum(x)
    y = x^2;
end

result = squareNum(4); disp(result);

medium

A. 16

B. 8

C. Error: Undefined function

D. 4

Solution

1. Step 1: Understand the function behavior

   The function squareNum takes input x and returns x squared (x^2).

2. Step 2: Calculate the output for input 4

   4 squared is 16, so the function returns 16.

3. Final Answer:

   16 -> Option A

4. Quick Check:

   4^2 = 16 [OK]

Hint: Square means multiply number by itself [OK]

Common Mistakes:

• Confusing square with doubling
• Expecting error due to function call
• Thinking output is input unchanged

4. Identify the error in this MATLAB function:

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

medium

A. No output variable declared

B. Function name does not match file name

C. Missing parentheses in function definition

D. Missing semicolon after y = a + b

Solution

1. Step 1: Check MATLAB syntax rules

   In MATLAB, statements should end with a semicolon to suppress output unless output is desired.

2. Step 2: Identify missing semicolon

   The line 'y = a + b' lacks a semicolon, which can cause unwanted output or warnings.

3. Final Answer:

   Missing semicolon after y = a + b -> Option D

4. Quick Check:

   Statements need semicolon to end [OK]

Hint: End statements with semicolon to avoid unwanted output [OK]

Common Mistakes:

• Ignoring semicolon importance
• Confusing function name and file name rules
• Thinking parentheses are optional

5. You want to organize a MATLAB program that calculates areas of different shapes. Which approach best uses functions to keep the code clean and reusable?

hard

A. Write all calculations in the main script without functions

B. Use global variables to store all shape dimensions and calculate areas inline

C. Write one function for each shape's area calculation and call them from a main script

D. Write one large function that calculates all shapes without inputs

Solution

1. Step 1: Understand modular design with functions

   Creating separate functions for each shape's area calculation groups related code and makes it reusable.

2. Step 2: Compare options for code organization

   Write one function for each shape's area calculation and call them from a main script uses functions properly; others mix code or use poor practices like globals or monolithic functions.

3. Final Answer:

   Write one function for each shape's area calculation and call them from a main script -> Option C

4. Quick Check:

   Functions for each task = Write one function for each shape's area calculation and call them from a main script [OK]

Hint: Use separate functions for each task to stay organized [OK]

Common Mistakes:

• Putting all code in one script without functions
• Using global variables unnecessarily
• Writing one big function for all tasks