MATLAB Variables and Workspace Interaction Questions and Answers

Question 1

Which of the following is an invalid variable name in MATLAB?

Accepted Answer

_var

Answer

A_Var

Answer

var_1

Answer

VarA

Question 2

A user has several variables in the workspace: `price_usd`, `price_eur`, `tax_rate`, and `quantity`. Which command would save only the variables related to price into a file named `prices.mat`?

Accepted Answer

save('prices.mat', 'price*')

Answer

save prices.mat price_usd, price_eur

Answer

save prices.mat all(price)

Answer

save('prices.mat', 'price_usd'; 'price_eur')

Question 3

What is the key difference between the `who` and `whos` commands?

Accepted Answer

`who` only lists variable names, while `whos` provides detailed information like size, bytes, and class.

Answer

`who` lists variables and their values, while `whos` only lists variable names.

Answer

`who` lists variables in the current function, while `whos` lists variables in the base workspace.

Answer

`who` is an obsolete function and has been replaced by `whos`.

Question 4

If the workspace contains a variable `x = 10`, and you execute the command `load('my_data.mat')`, where `my_data.mat` also contains a variable named `x` with the value `50`, what will be the state of the workspace variable `x` after the command completes?

Accepted Answer

The value of `x` will be overwritten and become `50`.

Answer

The command will produce an error due to a name conflict.

Answer

The value of `x` will remain `10`.

Answer

A new variable `x_1` will be created with the value `50`.

Question 5

What is the primary characteristic of a `persistent` variable in a MATLAB function?

Accepted Answer

Its value is retained in memory between calls to the function.

Answer

It is accessible from the base workspace after the function has been called.

Answer

It must be initialized to a non-empty value upon declaration.

Answer

It can be modified by other functions if they declare the same persistent variable.

Question 6

A user wants to remove all variables from the workspace but keep all loaded functions and MEX-files in memory. Which command should be used?

Accepted Answer

`clear variables`

Answer

`clear all`

Answer

`clc`

Answer

`clear functions`