MATLAB Data Types and Structures 5

Question 1

What is the difference between `==` and `isequal()` when comparing arrays in MATLAB?

Accepted Answer

`==` compares element-wise and returns an array; `isequal()` checks if arrays are identical and returns a scalar

Answer

`==` performs element-wise comparison returning a logical array, while `isequal()` returns a single true/false for whole-array equality.

Question 2

What happens when you assign `s(5).x = 10` to a struct `s` that only has elements 1-3?

Accepted Answer

Elements 4 and 5 are created; element 4 has empty fields and element 5 has x=10

Answer

MATLAB auto-expands struct arrays; intermediate elements (4) are created with empty (`[]`) field values.

Question 3

Which syntax correctly creates a string array (not cell array of chars) in MATLAB R2017a+?

Accepted Answer

string({"hello","world"})

Answer

string({...}) converts a cell array of chars into a string array; double-quoted literals like "hello" also create string scalars.

Question 4

What does `sparse()` create in MATLAB?

Accepted Answer

A matrix that only stores nonzero elements to save memory

Answer

`sparse()` creates a sparse matrix representation that stores only nonzero values and their indices, saving memory for large matrices with few nonzeros.

Question 5

How do you find all keys in a `containers.Map` object named `m`?

Accepted Answer

keys(m)

Answer

The `keys(m)` function returns a cell array of all keys in a `containers.Map` object.

MATLAB - MATLAB Technical Computing Practice Test

MATLAB - MATLAB Technical Computing Practice Test

MATLAB Data Types and Structures 5