Row and column vectors in MATLAB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this MATLAB code?

Consider the following MATLAB code that creates a row vector and a column vector. What will be the size of B after execution?

MATLAB

A = [1, 2, 3, 4];
B = A';

A 4 1

B 4 4

C 1 4

D 1 1

💡 Hint

Remember that the apostrophe (') operator transposes the vector.

The vector A is a row vector with size 1x4. Transposing it with ' converts it into a column vector with size 4x1.

❓ Predict Output

intermediate

What is the output of this MATLAB code?

What will be the output of the following code snippet?

MATLAB

v = [5; 10; 15];
result = v(2);

A 5

B 10

C Error: Index exceeds matrix dimensions.

D 15

💡 Hint

Indexing in MATLAB starts at 1 and works down the column for column vectors.

The vector v is a column vector with elements 5, 10, and 15. Accessing v(2) returns the second element, which is 10.

❓ Predict Output

advanced

What is the output of this MATLAB code involving vector multiplication?

Given the row vector r = [1 2 3] and column vector c = [4; 5; 6], what is the result of r * c?

MATLAB

r = [1 2 3];
c = [4; 5; 6];
result = r * c;

A 32

B [4 10 18]

C [4; 10; 18]

D Error: Inner matrix dimensions must agree.

💡 Hint

Matrix multiplication rules: number of columns in first must equal number of rows in second.

r is 1x3 and c is 3x1, so multiplication is valid and results in a 1x1 scalar: 1*4 + 2*5 + 3*6 = 32.

❓ Predict Output

advanced

What error does this MATLAB code produce?

What error will this code produce?

MATLAB

r = [1 2 3];
c = [4 5 6];
result = r * c;

A [4 10 18]

B 18

C Error: Inner matrix dimensions must agree.

D Error: Undefined function or variable 'result'.

💡 Hint

Check the dimensions of the vectors for matrix multiplication.

Both r and c are 1x3 row vectors. Multiplying two 1x3 matrices is invalid because the inner dimensions do not match.

🧠 Conceptual

expert

How many elements are in the resulting vector?

If you create a row vector R = 1:7 and a column vector C = (1:7)', what is the number of elements in the vector V = R + C'?

A 49

B Error: Matrix dimensions must agree.

C 1

D 7

💡 Hint

Check the dimensions of R, C, and C' before addition.

R is a 1x7 row vector, C is a 7x1 column vector, so C' is 1x7 row vector. Adding two 1x7 vectors results in a 1x7 vector with 7 elements.