Special matrices (zeros, ones, eye, rand) in MATLAB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the zeros(n) function do in MATLAB?

It creates an n-by-n matrix filled with zeros. For example, zeros(3) makes a 3x3 matrix where every element is 0.

beginner

How do you create a matrix of all ones with 2 rows and 4 columns in MATLAB?

Use ones(2,4). This creates a 2x4 matrix where every element is 1.

beginner

What is the purpose of the eye(n) function in MATLAB?

It creates an identity matrix of size n-by-n. This matrix has 1s on the diagonal and 0s elsewhere.

beginner

What does the rand(m,n) function generate in MATLAB?

It creates an m-by-n matrix filled with random numbers between 0 and 1. Each number is different every time you run it.

intermediate

How can you create a 4x4 identity matrix and then multiply it by 5 in MATLAB?

First create the identity matrix with eye(4), then multiply by 5: 5 * eye(4). This results in a 4x4 matrix with 5s on the diagonal and 0s elsewhere.

What will zeros(2,3) create?

A A 2x3 matrix of zeros

B A 3x2 matrix of zeros

C A 2x3 matrix of ones

D A 3x3 identity matrix

zeros(2,3) creates a matrix with 2 rows and 3 columns filled with zeros.

Which function creates an identity matrix in MATLAB?

A ones()

B eye()

C rand()

D zeros()

eye(n) creates an n-by-n identity matrix with 1s on the diagonal.

What range of values does rand(3,3) generate?

A Only 0s and 1s

B Random integers between 0 and 10

C Random decimal numbers between 0 and 1

D Negative and positive random numbers

rand generates random decimal numbers between 0 and 1.

How do you create a 5x5 matrix of all ones?

A zeros(5,5)

B rand(5,5)

C eye(5)

D ones(5,5)

ones(5,5) creates a 5x5 matrix filled with ones.

What does eye(3)*2 produce?

A A 3x3 matrix with 2s on the diagonal and 0s elsewhere

B A 3x3 matrix of twos

C A 3x3 matrix of zeros

D A 3x3 matrix of random numbers

Multiplying the identity matrix by 2 doubles the diagonal elements, leaving zeros elsewhere.

Explain how to create special matrices in MATLAB using zeros, ones, eye, and rand functions.

Think about what each function fills the matrix with.

Describe a real-life situation where you might use an identity matrix created by eye(n) in MATLAB.

Think about how multiplying by 1 keeps a number the same.