MATLAB Matrix and Array Operations 2

Question 1

What does the MATLAB expression `A(:, 2)` return for a 3×4 matrix A?

Accepted Answer

The second column of A

Answer

The colon in the row index selects all rows, so `A(:, 2)` returns the entire second column as a column vector.

Question 2

Which MATLAB function returns the number of elements in an array regardless of its dimensions?

Accepted Answer

numel(A)

Answer

`numel(A)` returns the total number of elements, equivalent to prod(size(A)).

Question 3

What is the result of `[1 2; 3 4] .^ 2` in MATLAB?

Accepted Answer

[1 4; 9 16]

Answer

The element-wise power operator `.^` squares each element individually, yielding [1 4; 9 16].

Question 4

How do you delete the third row of matrix A in MATLAB?

Accepted Answer

A(3, :) = []

Answer

Assigning `[]` to a full row slice `A(3, :)` removes that row from the matrix.

Question 5

What does `linspace(0, 1, 5)` produce?

Accepted Answer

[0 0.25 0.5 0.75 1]

Answer

`linspace(0, 1, 5)` creates 5 linearly spaced values from 0 to 1 inclusive: [0, 0.25, 0.5, 0.75, 1].

MATLAB - MATLAB Technical Computing Practice Test