FREE MATLAB Matrix Operations & Indexing Questions and Answers

Question 1

Given a matrix `A = [1 2 3; 4 5 6; 7 8 9]`, what is the result of `A(2, :)`?

Accepted Answer

[4 5 6]

Answer

[2 5 8]

Answer

[1 2 3]

Answer

[7 8 9]

Question 2

If you have a matrix `M = magic(3)`, which MATLAB command would correctly extract the element at the intersection of the second row and third column?

Accepted Answer

M(2,3)

Answer

M(3,2)

Answer

M{2,3}

Answer

M[2,3]

Question 3

Consider two matrices `X = [1 2; 3 4]` and `Y = [5 6; 7 8]`. Which of the following operations would result in `[6 8; 10 12]`?

Accepted Answer

X + Y

Answer

X * Y

Answer

X .* Y

Answer

X \ Y

Question 4

You have a matrix `B = rand(4, 5)`. Which command would correctly assign the value `100` to all elements in the first column of `B`?

Accepted Answer

B(:, 1) = 100

Answer

B(1, :) = 100

Answer

B(:, 1) == 100

Answer

B(1, 1) = 100

Question 5

Given `C = [10 20; 30 40; 50 60]`, what is the result of `C(end-1, 1)`?

Accepted Answer

30

Answer

10

Answer

50

Answer

60

Question 6

Which of the following describes the outcome of `D = [1 2; 3 4]; D(2, :) = []`?

Accepted Answer

The matrix D will become `[1 2]`.

Answer

An error will occur because rows cannot be deleted this way.

Answer

The matrix D will become `[1 2; 3 4]` (unchanged).

Answer

The matrix D will become `[1; 3]`.